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The interface between the passenger terminal building and the airside facilities of an airport is crucial to the achievement of safe and efficient aircraft operations. Accordingly, the terminal planner must be fully aware of and conform to specific airside planning regulations and require- ments. Specifically, the terminal planner needs to consider: â¢ Airside planning requirements â¢ Terminal apron planning â¢ Aircraft gate requirements V.1 Airside Planning Requirements The following airside constraints and functions must be considered in the site planning of the airport terminal complex: â¢ FAR Part 77 and TERPS requirements â¢ Aircraft maneuvering and separations â¢ Air traffic control tower line-of-sight â¢ Emergency equipment access roads â¢ Airside security â¢ Aircraft apron/gate access points â¢ Aircraft deicing â¢ Electronic interference Each of these planning considerations are applicable in principle to all airports but may be adjusted in relation to the actual complexity of aviation operations. Each of these items must focus on the specific needs of the airport for which a terminal plan is being prepared, and the scope of the study must be tailored to the individual airport. Therefore, in any given study, certain aspects of these airside functional areas may be emphasized, while others may not be considered at all. Each of these terminal airside planning considerations is presented in more detail in the following subsections. V.1.1 FAR Part 77 and TERPS Requirements The navigable airspace located around an airport constitutes a sizable area requiring optimum consideration and evaluation when determining the runway system. All airspace in proximity to airports is governed by FAR Part 77 (9). In addition, airports utilizing aircraft instrument approach and departure procedures may also fall under TERPS (10). Each of these two airspace planning criteria is discussed in more detail below. At the anticipated publication date of this Guidebook, the FAA intends to revise the FAR Part 77 standards to better incorporate TERPS requirements. 96 C H A P T E R V Terminal Airside Facilities
V.1.1.1 FAR Part 77 Imaginary Surfaces The purpose of FAR Part 77 is to protect the airspace and approaches to each runway from hazards that could affect the safe and efficient operation of aircraft. These standards can also be used by local jurisdictions in controlling the height of objects in the vicinity of airports. For example, the FAR Part 77 surfaces can be utilized in zoning and land use ordinances adjacent to an airport to protect the navigable airspace from encroachment by hazards that would potentially affect the safety of airport operations. The FAR Part 77 imaginary surfaces are established relative to the airport and runway system. The Part 77 imaginary surfaces include the primary, approach, transitional, horizontal, and con- ical surfaces as shown in Figure V-1. The dimensions of each imaginary surface are based on the runway approach capability (visual, non-precision, or precision) and are depicted in the data table in Figure V-1. Primary Surface. The primary surface is located closest to the runway environment. It is a rectangular area symmetrically located about the runway centerline and extending a distance of 200 feet beyond each runway end and varies in width from 250 feet for utility runways to 1,000 feet for precision instrument runways. Its elevation is the same as the runway centerline at a point perpendicular to the runway centerline. The width of the primary surface depends on the runway approach capability (visual, non-precision, or precision). The primary surface must remain clear of most objects in order to allow unobstructed passage of aircraft. Objects are only permitted if they are no taller than 2 feet above the ground and if they are constructed on frangible mounts. The only exception to this rule is for objects whose location is âfixed by functionâ such as navigational and visual aid facilities (glide slope, precision approach path indicator, windsock, etc.). Approach Surface. An approach surface is also established for each runway end. The approach surface has the same inner width as the primary surface and then flares out (gets wider) as it rises upward and outward along the extended runway centerline. The approach surface starts 200 feet beyond the runway ends. The slope of the rise and the length of the approach surface are dictated by the type of approach available to the runway (20:1 approach slope for visual, 34:1 approach slope for non-precision, or 50:1 approach slope for precision). The length of each approach surface is depicted in the data table shown in Figure V-1. Transitional Surface. Each runway has a transitional surface that begins at the outside edge of the primary surface and at the same elevation as the runway centerline. There are three transitional surfaces. The first is off the sides of the primary surface; the second is off the sides of the approach surface; and the third is outside the conical surface and pertains to precision runways only. The transitional surface rises at a slope of 1 foot vertically for each 7 feet of horizontal distance (7:1) up to a height that is 150 feet above the published airport elevation. Horizontal Surface. The horizontal surface is established at 150 feet above the published airport elevation (mean sea level). This surface is composed of swinging arcs of radii (5,000 feet in length for utility/visual runway and 10,000 feet in length for all other runways), beginning at the edge of the primary surface. Conical Surface. The conical surface begins at the outer edge of the horizontal surface. The conical surface continues for a distance of 4,000 feet horizontally at a slope of 1 foot vertically for each 20 feet of horizontal distance (20:1). All obstructions to the Part 77 imaginary surfaces should be identified and should be either removed or lowered so that obstruction height is below these surfaces. In some cases, it may be Terminal Airside Facilities 97
98 Airport Passenger Terminal Planning and Design Source: CFR, Title 14, Part 77 â Objects Affecting Navigable Airspace. Figure V-1. FAR Part 77 imaginary surfaces.
appropriate to mark and light the obstruction in accordance with FAA AC 70/7460-1 (18). This form can be downloaded and submitted electronically to the appropriate FAA Regional Office. Each obstruction must be reviewed by the FAA to determine if it constitutes a potential hazard to air navigation and, if so, to identify which course of action is appropriate. If removal, relocation, or lowering the height of an obstruction is not feasible, runway thresholds may need to be dis- placed or adjustments to the glidepath angle and threshold crossing height may be necessary. The guidelines for altering the latter, and the maximum and minimum values that are relevant, are located in FAA Order 8260.3B (10). V.1.1.2 TERPS Surfaces The U.S. Standard for TERPS criteria formulate, review, approve, and publish procedures for instrument flight operations at airports. For the purposes of this chapter, only the precision final approach and departure segment surfaces for obstacle identification purposes will be discussed. The TERPS final approach surface is divided into two areas: primary and secondary. For precision instrument approaches, the primary area consists of the âWâ and âXâ obstacle clearance surfaces (OCS), and the secondary area contains the âYâ OCS, as shown in Figure V-2. In addition, there are primary and secondary TERPS departure surfaces for the evaluation of obstacles during takeoff operations as shown in Figure V-3. Final Approach Surfaces. The TERPS final approach surface begins at 200 feet from the landing threshold point (LTP) or fictitious threshold point (FTP) and ends at the precision final approach fix. The âW,â âX,â and âYâ surfaces cohesively define the total approach surface, with the âWâ OCS running down the extended runway centerline, the âXâ OCS flanking the âWâ OCS, Terminal Airside Facilities 99 Source: FAA Order 8260.3B, U.S. Standard for Terminal Instrument Procedures (TERPS) Figure V-2. TERPS approach surfaces.
100 Airport Passenger Terminal Planning and Design and the âYâ OCS occurring on the sides of the âXâ OCS and making up the exterior of the TERPS approach surface. A cross section of these surfaces is shown in Figure V-4. Primary Area (âWâ and âXâ OCS). The âWâ OCS maintains a 34:1 slope and has a width of 400 feet (200 feet on each side of the runway centerline) at the beginning of the TERPS approach surface. The surface expands until it reaches a width of 2,200 feet at a distance of 50,200 feet from the LTP or FTP. The âXâ OCS runs along both sides of the âWâ OCS and has a width of 300 feet on each side. It extends out 50,200 feet at a slope of 4:1 and perpendicular to the final approach course where the dimensions eventually equate to 3,876 feet on each side of the surface. Secondary Area (âYâ OCS). The secondary area of the TERPS approach surface occurs on each side of the âXâ OCS and exists as the outer OCS for the TERPS approach surface. Each side of the âYâ OCS starts as 300 feet wide and extends out 50,200 feet at a slope of 7:1 in a direction perpendicular to the final approach path where the OCS ends at 2,500 feet at both sides. Departure Surfaces. The departure surfaces for TERPS begin at the departure end of the runway, or the end of the runway opposite the landing threshold. It has an inner width of 1,000 feet and splays outward at a rate of 10Â° relative to the departure course for a distance of two nautical 3,233 FT 985 M 3,233 FT 985 M 10,200 FT 3,109 M 10,200 FT 3,109 M 1,000 FT 305 M 500 FT 152 M Source: FAA Order 8260.3B, U.S. Standard for Terminal Instrument Procedures (TERPS) Figure V-3. TERPS departure surfaces.
miles. The primary area OCS slope occurs at 40:1, and the secondary area (only applicable when positive course guidance systems are identified) has a 12:1 slope. V.1.2 Aircraft Maneuvering and Separations When planning passenger terminal configurations and their adjacent aprons, it is important to consider the maneuvering patterns and paths of the aircraft that the facility will serve. These considerations are based mainly on the role the airport intends to play. For example, aircraft type, terminal configuration, number of gates, and configuration of the runways all greatly affect the way aircraft maneuver and operate on and around the terminal apron area. V.1.2.1 Dual vs. Single Apron Taxiways/Taxilanes A major concern for airports with a large number of gates is maintaining an uninterrupted taxi flow both to and from the aircraft gates. This flow can be accomplished through the use of two or more parallel taxiways/taxilanes. Dual parallel taxiways/taxilanes enable one or more aircraft to be pushed back or taxi in one direction, while aircraft are moving in the opposite direction on the parallel taxiway/taxilane. Dual parallel taxiways/taxilanes provide for increased flexibility in accessing the terminal gates during peak operating periods. V.1.2.2 Taxiway and Taxilane Separations A taxiway is a defined path established for the taxiing of aircraft from one part of an airport to another. A taxilane is a portion of the aircraft parking area used for access between taxiways and aircraft parking positions. Aircraft taxi speeds on a taxilane are less than that on a taxiway. Taxiways are part of the airportâs movement area controlled by the FAA ATCT while taxilanes are considered non-movement areas and generally not controlled by the ATCT. When planning for parallel taxiways/taxilanes, it is important to ensure that there is adequate separation between centerlines to accommodate the appropriate design aircraft based on the aviation demand forecast. The airfield components should be designed using either the FAA or ICAO current guidelines as shown in Table V-1 and Table V-2 for the specific airplane design groups. The use of these planning standards will provide for adequate aircraft wingtip and obstacle clearance. V.1.3 Air Traffic Control Tower Line-of-Sight For the safety of aircraft operations, the ATCT must have a clear line-of-sight to all movement areas (runways, taxiways, and ramps) on the airfield. This requirement will need to be considered during the terminal site analysis and design. The aircraft parking configuration and tail heights Terminal Airside Facilities 101 OCS OCS ASBL 2500 3876 2200 2200 3876 2500 762 1181 671 671 1181 762 FT M FT M Cross Section At 200 FT/61 M from RWT Y 1:7 GQS W X 1:4 Y 1:7 Y 1:7 Y 1:7 X 1:4 X 1:4 X 1:4 W Cross Section At 50,200 FT/15,001 M from RWT 300 300 400 400 300 300 91 91 122 122 91 91 700 FT 213 M 6,076 FT 1,852 M 6,076 FT 1,852 M 700 FT 213 M Source: FAA Order 8260.3B, U.S. Standard for Terminal Instrument Procedures (TERPS) Figure V-4. Cross section of TERPS surfaces.
will also need to be considered because they can result in line-of-sight shadows from the ATCT. The controller must be able, at a minimum, to see the fuselage of all aircraft operating on the airfield. In addition, it is desirable to have a clear line-of-sight from the ramp tower(s) to view the aircraft entering the terminal apron area and progressing to their gate position. The ramp controller should at least be able to maintain visual contact with the tail of the aircraft within the ramp area. The strategic positioning of video cameras at the gate area and around the terminal apron can support these requirements. Where there is no ramp tower present, it is important for the ATC to have a clear view of all aircraft ramp areas. V.1.4 Emergency Equipment Access Roads To achieve the recommended response time for emergency equipment access to the aircraft gate area, a number of design variables should be analyzed. The width and vertical clearance of the emergency access roadway should allow for the largest emergency vehicle deployed to clear any obstacle. When the surface of the road is indistinguishable from the surrounding area, or in areas where snow may obscure the location of the roads, edge markers should be placed at adequate intervals to provide visual reference. The emergency access road should be designed to have as few turns as possible. The turning radii must be designed to allow emergency equipment to safely 102 Airport Passenger Terminal Planning and Design FAA Airplane Maximum Typical Design Group Wingspan Aircraft Feet Meters I. Small Regional 49 15 Metro II. Medium Regional 79 24 SF340/CRJ III. Narrowbody/Lrg. Regional 118 36 A320/B737/DHC8/E175 IIIa. B757(winglets) 135 41 B757 IV. Widebody 171 52 B767/MD11 V. Jumbo 214 65 B747,777,787/A330,340 VI. Super Jumbo 262 80 A380/B747-8 Note: The FAA considers all B757 aircraft as part of ADG IV. However, for gate and holdroom planning purposes, the B757 has more characteristics in common with AGD III aircraft than the rest of the widebody aircraft in ADG IV. Source: FAA AC 150/5300, Change 12, ICAO Annex 14 Table V-1. FAA airplane design groups. I II III IV V VI A B C D E F Taxiway Centerline to: Parallel Taxiway/ Taxilane Centerline 69 105 152 215 267 324 23.7 33.5 44 66.5 80 97.5 Fixed or Movable Object 44.5 65.5 93 129.5 160 193 16.2 21.5 26 40.5 47.5 57.5 Taxilane Centerline to: Parallel Taxilane Centerline 64 97 140 198 245 298 n.a. n.a. n.a. n.a. n.a. n.a. Fixed or Movable Object 39.5 57.5 81 112.5 138 167 12 16.5 25.5 36 42.5 50.5 ITEM FAA ADG (FT) ICAO ARC ELEMENT 2 (M) Source: FAA AC 150/5300, Change 12, ICAO Annex 14 Table V-2. Taxiway/taxilane separation standards.
maneuver through turns. Adequate separation between aircraft wingtips should be provided to allow vehicle access to all aircraft gate/stand positions and the terminal building. In addition, adequate staging areas should be provided at various points along the terminal to provide space for emergency vehicles so they do not block aircraft gate positions for an extended period. V.1.5 Airside Security For purposes of this airside security overview, the airside of an airport consists of all those parts of the airport that are not open to access by persons other than those who have been screened and duly authorized to enter those areas. In most airports, the airside also consists of those parts of the terminal that can only be accessed by passengers and staff that have passed through a security screening process, and all parts of the airfield and structures that have direct access to the airfield. Table V-3 provides an overview of the various areas of concern that are involved in securing the airportâs airside operation. As is apparent from Table V-3, a principal technology used in securing these diverse functional areas of the airportâs airside is video analytics, which is video imagery technology combined with a computer program. Video imagery technology allows security personnel to monitor numer- ous areas simultaneously, covering the vast distances associated with the numerous and diverse locations of these security areas of concern. Video analytics is simply a sophisticated computer program integrated with the closed circuit television (CCTV) camera system that can be programmed to respond to very specific types of movements or events within its field of vision. At an airport with hundreds of cameras, it is not possible for an operator to give equal attention to all of them; therefore, the analytics program is tuned to watch everything but to respond primarily to anomalies. This is a significant labor-saving âforce multiplier,â which allows the operator to focus only on those areas where something out of the ordinary is occurring and to initiate law enforcement and other asset response only where necessary. Terminal Airside Facilities 103 Areas of Concern Threat Principal Technology 1. AOA/outer perimeter boundaries Unauthorized access Persons and vehicles Anomalous behavior, at and beyond perimeter Multi-sensor, including Video Analytics 2. Vehicle access gates Unauthorized access Persons and vehicles Video Analytics Access Control 3. Employee access portals Unauthorized access Persons Video Analytics Access Control 4. Terminal lobbies and external access to AOA Unauthorized articles, Improvised explosive devices (IEDs) Video Analytics 5. Terminal roadways Vehicle-borne IEDs Video Analytics Access Control 6. Passenger screening checkpoints Security breaches Exit lane Video Analytics Source: TranSecure Table V-3. Overview of threat and principal technology used in areas of concern at an airport.
Video analytics however carries a very important caveat. The mathematical algorithms are complex, and very specific; they are written to address a specific concern at a given location within certain parameters. For example, the analytics of one camera may be watching a particular segment of fence line, masking certain backgrounds and peripheral motion, creating narrowly defined virtual zone lines as âtrip wiresâ for pedestrian intrusions in one direction but not others. That series of algorithms will not work for a surveillance camera used at a vehicle gate to differentiate among large and small vehicles with different physical characteristics traveling at different speeds and directions or for an indoor camera watching for congestion, abandoned bags, or piggy-backing and may not work at all at night or when weather or lighting conditions are less than optimal. Further, as the initial sets of rules are established for monitoring ânormalâ conditions, however those might be defined, there will also be changes in threat conditions, issuance of new TSA Security Directives, and other modifications of what and where to look for anomalies. All of these occasions will require changes in the algorithms that define alerts and alarms and, equally important, changes in the response procedures for the operator and law enforcement responders, both in volume of alerts and where resources must be directed. These changes cannot be made by âon-offâ switches at the security operations center (SOC); they are re-programming concerns to be addressed in the initial procurement process and during the establishment of the baseline operating rules. Although the outer air operations area (AOA) portions of the perimeter may be long fence lines surrounding remote facilities that are well removed from commercial passenger activity, other security areas of concern are at the center of such activity. Whether in a single- or multiple- terminal environment, the terminal and operational buildings themselves are also typically part of the close-in perimeter and become a key security concern both externally, where the fences meet the building walls, and internally, where physical and electronic boundaries separate the public landside from the secured operational airside. Other security areas of concern include employee and tenant access points, both inside and out; loading docks adjacent to roadways and vehicle and pedestrian gates; and the TSA screening checkpoint. To some degree, the public approach roads and curbside are also included, where vehicle-borne improvised explosive devices (VBIEDs) can approach unprotected public areas and persons as well as initiate breaches into the close-in terminal environment. Although many of those elements extend beyond the scope of this terminal planning guidebook, each of them has an impact, not only on how the passenger terminal design will accommodate the security system, but also on the design of the underlying IT network. The IT network connects the security system and transmits data to and from every point on the system and ultimately to an SOC, typically in the terminal, which collects data and initiates responses to alerts and alarms. The key point is that terminal security concerns cannot be isolated from the rest of the airportâs overall technology infrastructure; there must be a single integrated network that supports the key objectives of detection, situational awareness, and domain awareness as well as the communications and data retention and analysis capabilities necessary for immediate response to events. Detection = Situational Awareness = Domain Awareness â¢ Detection is the ability to âseeâ virtually everything of interest that is happening in real time, whether by visual cues, electronic signals from sensors, or any other means of data collection and convergence that can identify eventsâor in some cases, a non-event, such as a left parcel or inappropriately parked vehicle. Detection is the necessary first step toward prevention, or at least mitigation before problems occur. â¢ Situational awareness is about identifying anomaliesâwhich may or may not be security- related events. It is the ability to make sense of the accumulation of dynamic data by identifying, 104 Airport Passenger Terminal Planning and Design
categorizing, collating, organizing, analyzing, and prioritizing in the context of rapidly changing security environments. â¢ Domain awareness is the ability to see and understand oneâs total environment and to manage eventsâpossibly multiple simultaneous eventsâas they continue to evolve. This ability requires not only the technology to accomplish that mission, but also the necessary motivation, training, and experience to utilize the technology to its best advantage. Recent trends in networking technology and readily available low-cost and high-bandwidth communication links have nearly eliminated the concepts of time and distance in terms of sharing data and information. These trends have significant implications on an airportâs surveil- lance and response needs, the centralized command and control capabilities to direct them, and the ability to establish the necessary infrastructure and operational upgrades to share data with multiple users. The primary SOC where the information is collected, analyzed, and distributed can be housed anywhere, including the terminal, but the need for airport-wide infrastructure to support the security system remains constant, including in many cases, the need for a redundant backup SOC facility for emergency and incident response management. It should also be noted that the SOC may or may not be co-located with the day-to-day airport operations center (AOC) or the emergency operations facility. The three centers serve very different functions, although such space-sharing arrangements are not uncommon, particularly at smaller airports. V.1.5.1 Security Terminology Definitions TSA terminology for various security-related areas in an airport environment is not the same as the operational definitions of the FAA, the CBP, or other federal agencies. Further, TSA security concerns differ from those of local law enforcement issues such as vehicle traffic, parking lots, or common criminal activity such as theft or assault. Nonetheless, both have an impact on terminal planning and must be coordinated with TSA and relevant law enforcement agencies. The TSAâs generic regulatory terms for security areas are defined in Â§1540.5, and further refined in other subsections of regulatory language for secured areas (Â§1542.201), air operations areas (Â§1542.203), and security identification display areas (Â§1542.205). However, each airportâs site-specific definitions, descriptions, and boundaries are found only in its written Airport Security Program (ASP); most airports have unique physical and operational characteristics that often blur the boundaries and transitions of some security areas. Generally, those areas can be described as follows: â¢ Terminal: The area fully accessible to the general public, with no screening or regulatory security constraints beyond perhaps general CCTV or law enforcement surveillance. â¢ Sterile area: The area after passengers have gone through the security screening checkpoint, including waiting areas and some concessions, up to the door(s) with controlled access to the loading bridge (âloading bridgeâ is the generic term; âJetwayâ is a specific brand name) and/or doors to the ramp. â¢ Secured area: The most robustly protected of the regulatorily mandated areas, generally immediately outside the terminal where aircraft load and unload and service functions such as catering and fueling take place, and specifically including baggage make-up areas. There might be multiple secured areas where, for example, an airport has both main and remote terminals. Secured areas must have access control measures in place that meet TSA Â§1542.207 require- ments and must meet various procedural requirements such as personnel background checks, ID display and challenge measures, and security training. â¢ Security ID display area (SIDA): Similar to a secured area, the SIDA relates only to ID display and challenge procedures. A SIDA does not require access controls and is not necessarily con- tiguous with a secured area; it may occur in physically separate areas, such as a fuel farm or Terminal Airside Facilities 105
maintenance area, but is still within airport-protected boundaries such as the air operations area perimeter. Note: Therefore, a secured area is always a SIDA (requiring ID display), but a SIDA is not necessarily a secured area (no access control requirement, although many do incorporate them as an extra measure). â¢ Air operations area: Similar to the FAA operational definition, the AOA is where aircraft maneuver, including runways, taxiways, ramps, etc. From a security perspective, its boundary is typically the perimeter fence, which will also have basic access controls; the distance and response time to the main concerns of the terminal and loading aircraft are typically deemed an adequate buffer zone for security purposes. â¢ Restricted area: TSA does not operationally or regulatorily define a restricted area at all, although many airports use the term in their ASP for such areas as cash rooms, communications closets, utility rooms, or other areas where there is a technical or procedural reason for restricted access but no TSA-related requirement to do so. â¢ Clear zone: Similarly, there is no regulatory security definition or requirement for a clear zone, although in the general context of best practices, it is typically seen as an obstacle-free cleared area of a few feet inside and/or outside a security fence line. V.1.5.2 Vehicle and Pedestrian Gates and Portals Although the design of each individual access point is usually very site specific, collectively they serve the same purpose: maintaining the integrity of the secured areas of an airport. They are typically tied to the integrated access control/CCTV surveillance system, so although they are often different in physical design, they must be consistent in their electronic characteristics to be of value in the airport-wide system and to operate within the policies and procedures of the Airport Security Program. It is not the goal of this document to provide specific types of individual design; there are literally dozens of common and perfectly acceptable types of hardware and softwareâaccess control and ID badging systems, cameras, key locks, doors, and gates. Security specialists can assist the designer in specifying appropriate equipment, but the designer must first consider the types of traffic at each access point, and the levels of security necessary for each area, to bring about an optimum system design. For example, where a simple chain and padlock might suffice on a remote fence gate that is used only rarely by grass mowers, it is much more critical, and common, for high-throughput doors leading from public areas in and around the terminal into the secure areas where aircraft and service vehicles operate to have an electronic system that, by regulatory mandate (Â§1542.207), must be able to differentiate and allow entry only to those persons authorized for access to that area. This introduces the relatively new topic of biometrics. With the traditional magnetic stripe or proximity access control card, one need only swipe the card or other token, and perhaps enter a personal identification number, to gain entry. Thus, the simple possession of a lost, stolen, or borrowed card might provide any holder with immediate access to the security areas. Biometrics adds the third element of oneâs own unique biometric identifier, such as a fingerprint or iris scan, so that only the authorized user can activate the system. There is extensive new guidance available in Integrated Security System Standard for Airport Access Control (31). The document contains much more than standards and guidelines for airport security access control; it is a full systems approach to facility security including operational requirements, perimeter intrusion detection, video surveillance, access control with the stress on biometric user authentication, and responder communications. These standards present functional require- ments and performance characteristics for use by designers, manufacturers, service providers, operators, and users of automated systems. 106 Airport Passenger Terminal Planning and Design
V.1.5.3 Planning for Vehicle Checkpoints TSA regulations do not require airports to carry out a comprehensive security program in public areas well removed from the terminal(s) and outside of the secure areas. But any attack or civil disturbance at a domestic airport could be catastrophic, particularly at close-in points; therefore, some degree of planning for such possibilities is in order. Attacks on the airsides of airports launched through vehicle access gates have been relatively rare events. A threat perpetratorsâ principal motivation could be to commandeer or destroy aircraft or to simply create damage and chaos. Any common vehicle approaching the airport perimeter may constitute an anti-aircraft IED âTrojan Horseâ and is a potential threat, because an IED capable of destroying an aircraft could have a volume of less than 12 fluid ounces (the volume of a soda can) and be in almost any imagina- ble shape. Mitigation of this threat requires an integrated perimeter security system designed to produce the maximum degree of deterrence, detection, and delay, in order to facilitate the most timely and effective response. Mitigation becomes more difficult if it is judged necessary to also screen cleared employees at perimeter vehicle and personnel entrances before allowing them access to the secure area. In the framework of risk management, there is a disparity between screening known workers for weapons and IEDs (or their components) as they enter a secure area and ensuring that complex vehicles and their random occupants not be used to bring in the same objects. The use of a well-planned airside vehicle security program is essential to the design and implementation of an integrated perimeter security system. Airport vehicle access gates are most often controlled by physical barriers and manned checkpoints monitored by CCTV. Todayâs typical fence-gate barriers have relatively low stopping capability, which presents a significant vulnerability. Main vehicle gates, particularly those adjacent to terminals, should consider a barrier capable of meeting the minimum threat of a 65,000 pound vehicle at 50 mph, producing kinetic energy of 5.5 million foot-pounds. (Estimate is based on a dump truck typically used during airport construction.) Video technology options also apply to vehicle gate security. Radar may assist in following identified targets within the perimeter to some degree but does not provide actionable imagery of vehicles or persons in a high-clutter environment. Measures that apply generally to unmanned gates include strategically placed bollards or remotely operated pop-up barriers as well as dedicated CCTV and analytics software for assessment of activity. For certain gates requiring a higher level of control for vehicle passage, either physical or virtual sally port designs should be considered. Sally ports are designed so that only one of the paired gates can be open at a time. The space between the gates must be sufficient to accommodate the largest semi-trailers allowed to enter at that portal. Manned guard posts are recommended to have a protected guard booth with a full range of security communications and CCTV monitoring capabilities, as well as computer network access for validating credentials. CCTV cameras, enhanced with video analytic functions, are an excellent means of virtually assessing vehicle passage through gates. Video analytic programming may change with the TSA threat levels and can include related video functions such as optical character recognition (OCR) of vehicle license plates for verification or under-vehicle inspection. The guard booth itself should be inside the fence or other barriers; CCTV will monitor both vehicle and personnel loitering, and can be used in the sally port example above to confirm that authorized vehicles remain in place until the gate has closed. Note that while many of these items are procedural and technology oriented, their success still derives from the initial planning and design decisions that determine their location and Terminal Airside Facilities 107
their operational and infrastructure capabilities. In addition to technology options, additional operational items to be considered during the terminal design include the following: â¢ Reduce the number of vehicles that require airside access. In some design scenarios, that could mean leaving receiving docks and marshaling areas outside the perimeter. â¢ Minimize access points where goods and concessions will be delivered. Consider redesign or moving primary point of concession acceptance to low-traffic areas. â¢ Integrate the airport vehicle permit program with managed biometric ID systems, to validate both the vehicle and driver. This higher degree of confidence may allow the design of close-in access points. â¢ Implement full communications capabilities at all manned vehicle gates for contact with the SOC and primary first responders. â¢ Create pedestrian access portals at vehicle gates with appropriate CCTV surveillance and biometric authentication capability. This discussion leans primarily on procedural solutions. No physical system, gate, camera, perimeter fence, lock, or any other component or system is âtheâ sole answer; all are entirely dependent on not only the whole of the physical system design and placement and the IT infra- structure that supports it but also the strength of the policies and procedures surrounding their implementation. V.1.5.4 Apron Areas Once a person is inside the controlled doors and gates, security on the ramp is almost exclusively procedural, depending largely on the willingness and capability of the employee community to remain aware of the persons and operations around them and to remain vigilant regarding ID badges or unusual behavior, while also performing their own responsibilities. Some technology assistance is available, such as CCTV and video analytics that can maintain watch over persons and equipment crossing virtual alert lines, although that is the very nature of most work on the apron and may be difficult to monitor effectively. Technology might also be employed to limit vehicles on the airside to pre-approved equipment with ignitions operated only by biometrically enrolled drivers. In the context of terminal design, however, perhaps the most consistently effective approach is a strong biometrically enabled access control system and CCTV surveillance at the portals (along with accompanying procedures), so that the ramp population is rarely infiltrated in the first place. After successful entry, employee vigilance is the best preventive measure. V.1.6 Aircraft Apron/Gate Access Points Aircraft access the terminal gates via the taxiway and taxilane system. The positioning of these taxi access points can vary based on the terminal and airfield configurations. In some cases it is helpful for the pilots to utilize gate access points for direction to and from the apron area. Aircraft access points to the terminal gate area will generally appear as the aircraft transits through the taxiway entrance onto the apron, while indicators for gate access points will be located on the taxilanes within the terminal apron. Apron entrance pavement markings are placed to provide pilots with visual direction toward the terminal and gate areas. They can also assist pilots in finding their position on the apron, which can be difficult to pinpoint when long distances separate terminals and taxiway access points. The location for these types of markings occurs approximately 7 feet from the taxiway centerline on the side the aircraft will be turning toward the apron. Figure V-5 illustrates such markings. Specific gate access points appear in the form of pavement markings that indicate gate iden- tification signs and are highly beneficial in times of low visibility on the airfield. Painted gate 108 Airport Passenger Terminal Planning and Design
identification signs can be placed in close proximity of terminal buildings and are located alongside taxiway centerlines on the side that the aircraft should turn toward the gate. These markings may display one or more rows of gate designations, such as a range of gates located in a particular direction or area. V.1.7 Aircraft Deicing There are two general forms of aircraft deicing: decentralized deicing and centralized deicing. Decentralized deicing usually takes place at the aircraftâs gate before push-back. While this form of deicing does not require the construction of a dedicated deicing apron, collection of spent deicing fluids is required and needs to be taken into account when planning the apron drainage collection system. One potential concern with deicing at the terminal gate is the increased holdover time between application of the deicing fluids and taxiing to the runway end for depar- ture. The taxi time between the gate and departure will need to be considered because of the amount of time that glycol will prevent ice from forming on the aircraft surfaces (approximately 10 to 15 minutes depending on weather conditions). Centralized deicing usually requires the construction of a dedicated deicing apron, which can be located just outside the terminal gate area or close to the runway departure ends. Some advantages of a centralized deicing operation include maintaining better control of collecting spent deicing fluids, freeing up the gate area for arrivals, reducing taxi distance to the departure runway ends, minimizing vehicular traffic in the gate area, minimizing the need for secondary deicing, and providing for a common-use deicing operation. In some cases it may be appropriate to provide remote deicing facilities located near departure runway ends or along taxiways when taxiing times from terminals or other centralized deicing facilities exceed holdover times. In this condition it will be important to ensure that the aircraft and mobile deicer boom heights are not in violation of the Part 77 imaginary surfaces. V.1.8 Electronic Interference During development of the terminal building and aircraft parking apron areas, it is advisable to determine if these proposed terminal facilities will interfere with any existing or future ground Terminal Airside Facilities 109 Apron Entrance Point 7-foot (2-meter) dimension is from near edge of the centerline to the edge of the sign. Detail of Apron Entrance Point Note: Centerline at apron entrance point locations may be marked with a radius marking rather than with a âTâ configuration as shown. 7 FT / 2 M TYP 7 FT / 2 M TYP Source: FAA Advisory Circular 150/5340-1J Figure V-5. Surface painted apron signs.
navigational aid (glide slope, localizer, DVOR/DME, etc.) and airport surveillance radar (ASR) facilities. It will be necessary to use computer modeling to analyze these potential impacts. V.2 Terminal Apron Planning Criteria Planning criteria for the terminal apron, combined with the analysis of aircraft gate requirements, drive the general configuration and the area required for the airside component of the terminal complex. These criteria cover the following: â¢ Aircraft gates and parking positions â¢ Aircraft gate wingtip clearances â¢ Aircraft parking guidance systems â¢ Apron gradients â¢ Blast fences â¢ Apron service roads â¢ Aircraft servicing â¢ Ground service equipment storage â¢ Apron lighting â¢ Apron snow removal V.2.1 Aircraft Gates and Parking Positions The aircraft gate/stand is a designated area intended for parking an aircraft so that passengers and cargo can be loaded and unloaded. For simplicity the term âgateâ will be used. The gate is the inter- face between passenger and aircraft flow. This section is devoted to discussing the multiple forms of aircraft gates/stands and the attributes that should be considered when planning these facilities. V.2.1.1 Gate/Stand Capacity and Fleet Mix When discussing airport capacity, there are two different forms of capacity: dynamic capacity (i.e., airfield capacity as it is related to the flow of aircraft on and around the airfield) and static capacity (i.e., gate capacity as related to the ability to accommodate aircraft). Gate capacity is defined as the maximum number of aircraft that a fixed number of gates can accommodate during a specified interval of time (typically 1 hour). Gate capacity is affected by a number of factors including but not limited to the following: â¢ The number and type of gates available â¢ The fleet mix demanding apron and gate space â¢ The use of passenger loading bridges or ground passenger loading â¢ Any operating restrictions on the use of any or all gates The nomenclature âgateâ is typically associated with an aircraft parking position situated at a terminal building and is often referred to as a âcontactâ gate. Aircraft parked remotely from a terminal building on an apron area reached by a bus operation is frequently referred to, partic- ularly outside of the United States, as âremote standâ or âstand.â Consistently using this set of nomenclature assists in differentiating the location and functional capability of a particular aircraft parking position. From a macro prospective, gates and stands are sometimes referenced by one of three broad aircraft size categories: widebody, narrowbody, and commuter or regional. A reference to widebody aircraft typically includes ADG IVâWidebody, ADG VâJumbo, and ADG VIâSuper Jumbo from the FAA AC 150/5300-13. In essence this includes all aircraft that have two aisles with the exception of the B757, which has a wingspan that falls into ADG IV but only contains a single aisle. The term narrowbody includes ADG III aircraft. The term regional includes the FAAâs large and small commuter/regional categories of ADG I and II, respectively. 110 Airport Passenger Terminal Planning and Design
To maximize gate capacity, it is recommended to plan gates so that they are as flexible as possible. Various arrangements are used both in the United States and overseas to accomplish this goal. The IATA Airport Development Reference Manual shows one approach referred to as the Multi-Aircraft Ramp System (MARS). Figure V-6 depicts the basic MARS configuration adapted to include a tail-of-stand ground service roadway as opposed to the head-of-stand road typically used at most overseas airports. MARS is a modular approach that allows two narrowbody aircraft to operate independently within the same footprint area of typically a Jumbo or Super Jumbo utilizing the same two loading bridges to serve all three aircraft positions. Another approach for optimizing gate flexibility is show in Figure V-7. This configuration is similar to the MARS but is not based around a specific aircraft module with service roads in-between. In the example shown in Figure V-7, gate use flexibility is achieved by parking multiple types of aircraft along the same flightline of the building with different lead-in lines per aircraft type, serviced by appropriately situated loading bridges. While obtaining a slightly higher density of aircraft along a comparable MARS wingspan frontage, this approach does require more loading bridges to achieve its flexibility of use. An operational approach for optimizing gate/stand capacity is to maximize flexibility by pre- venting operational or airline preferential restrictions on gate usage. Reserving gates/stands for specific airlines or aircraft types can cause major capacity limitations because certain gates are not used to optimize the number of aircraft turns (an arrival or departure) that could be accommodated Terminal Airside Facilities 111 Source: IATA Airport Development Reference Manual, 9th Edition, Jan 2004; modified for U.S. equivalent by Landrum & Brown Figure V-6. Example of MARS with widebody aircraft.
during the period of the day. Common-use aircraft gates are another means to maximize gate capacity. V.2.2 Aircraft Gate Wingtip Clearances Minimum wingtip clearances will vary by ADG or ICAO code. Table V-4 presents the current planning criteria contained in FAA AC 150/5 and ICAO Annex 14 (32) when planning for gate wingtip clearances. These requirements are considered to be minimal. Most airports will require wider separation for ADG II and III, typically 20 and 25 feet, respectively. Additionally, it is important to consult with the planned airline/tenant of the terminal facility because many airlines have their own wingtip separation requirements that are different from those recommended by the FAA or ICAO. V.2.3 Aircraft Parking Guidance Systems V.2.3.1 Visual Docking Guidance System A visual docking guidance system should be provided when it is intended to indicate, by a visual aid, the precise positioning of an aircraft on an aircraft gate/stand and when other alternative means, such as wing walkers, are not practicable. 112 Airport Passenger Terminal Planning and Design 3 B747-400's or 4 B767-300's 156FT /48M 156FT /48M 156 FT /48M 156FT /48M 213FT / 65M 213FT / 65M 689FT / 210M 699FT / 213M 25F / 7.5M 25F / 7.5M 25F / 7.5M 213FT / 65M 25F / 7.5M 25F / 7.5M Source: Landrum & Brown Figure V-7. Aircraft parking flexibility. FAA AIRPLANE DESIGN GROUP ICAO AIRCRAFT CODE LETTER WINGTIP CLEARANCE (FT/M) I A 10 / 3 II B 10 / 3 III C 15 / 4.5 IV D 25 / 7.5 V E 25 / 7.5 VI F 25 / 7.5 Source: FAA Advisory Circular 150/5 and ICAO Annex 14 Table V-4. Aircraft gate wingtip clearances.
Several factors need to be considered when evaluating the need for a visual docking guidance system. Those factors include the number and type of aircraft using the aircraft gate/stand, weather conditions, the available space on the apron, and the degree of precision required for maneuvering due to aircraft servicing installations, passenger loading bridges, and other obsta- cles. Design requirements for a visual docking system include both azimuth and stop guidance displays. Various types of visual docking systems can satisfy the operational requirements and specifi- cations. Figure V-8 illustrates a visual docking guidance system that uses a graphical display and laser-based sensors to provide azimuth guidance, distance to go, and stopping position. V.2.4 Apron Pavement Design Gradients on an apron should be sufficient to prevent accumulation of water or deicing fluids on the surface of the apron but should be kept as level as these requirements permit. As a general rule of thumb, for the ease of fueling, towing, aircraft taxiing, and the collection of excess deicing fluids, apron gradients should never exceed 1%. In areas where aircraft are being fueled, every effort should be made to keep the apron slope within 0.5%. However, local laws and ordinances should be consulted to ensure their requirements are also met. At the beginning of the apron pavement design process, the Airplane Characteristics for Airport Planning manuals for the critical aircraft should be consulted. These manuals, produced by the aircraft manufacturer and available on its website in most instances, provide designers with the maximum loads exerted on single points of pavement based on aircraft landing gear configurations. Using this information, the pavement structure and load bearing strength can be determined by using the current version of FAA AC 150/5320-6 (33). V.2.5 Blast Fences The use of a blast fence may be necessary in order to mitigate the potential effects of aircraft engine jet blast at vulnerable parts of the airport. Blast fences are regularly used in terminal apron areas where aircraft routinely taxi within close proximity to the terminal, ground equipment, and ramp personnel. They can also be located near runway end areas, run-up pads, and other locations that require shielding of airport pedestrian or vehicular traffic. When possible, the blast fence should be located outside of the runway and taxiway object-free area and should not penetrate the obstacle-free zone surface. Additional consideration should be given to its location relative to navigational aid critical areas. Blast fences are typically constructed using metal or concrete barriers that can consist of perforated, corrugated, louvered, or smooth surfaces. In some cases, the blast fence should be located on frangible mounts if it is within close proximity of aircraft takeoff and landing operations. In addition to the use of blast fences, any natural or man-made surface (earth berm) positioned between the aircraft engine and protected areas can be considered for jet blast protection. V.2.6 Apron Service Roads There is a shared responsibility between the airport operator and airlines to reduce risks involving aircraft-to-vehicle and vehicle-to-vehicle conflict when regulating vehicular traffic movement on or around the airfield. When possible, designated service roads should be provided because they restrict service vehicle movements to a confined area and provide routes where aircraft pilots are familiar with seeing vehicular activity. Factors to consider when designing service roads for accommodating existing and projected vehicular and GSE movement include space, sufficient bearing strength, height clearance, proper separation from runways and taxiways, and turning radii. In addition, secure access points need Terminal Airside Facilities 113
114 Airport Passenger Terminal Planning and Design Source: Jeppesen Sanderson, Inc., 2009 Figure V-8. Visual docking system.
to exist to prevent any unauthorized entrance from public or non-service vehicles to the area. Such points may consist of fencing, monitored gates, and/or manned entrances and would allow maintenance, fire and rescue, fuel, baggage, freight, and aircraft service vehicles access to the roads. If service roads pass beneath the terminal complex, access points to and from the service road and the terminal should be thoroughly secured as well. The service road width depends on the anticipated level of traffic on the roads, and each lane of service roads should be of minimum width to accommodate the widest equipment used on the road. If service roads involve cargo operations, they should be able to support unit load device transporter equipment between cargo terminals and aircraft, and exclusive use of part of the roadway system may become necessary by some categories of vehicles, such as unusually wide or high vehicles. As a minimum, the apron service road should have one lane in each direction with an overall width of 24 feet (12 feet each lane). In high-congestion areas it may be necessary to include a separate turn lane (12 feet wide) to provide vehicle-queuing and by-pass capability. V.2.6.1 Configurations of Apron Service Roads Three configurations exist for apron service roads, and they are identified based on location relevant to an aircraftâs parked position: tail-of-stand/apron edge, head-of-stand, or between aircraft. Tail-of-Stand/Apron Edge. Tail-of-stand service roads positioned behind aircraft, also known as apron edge service roads, are typically routed along the edge of the aircraft parking apron, outside of taxiway or taxilane clearance areas, and along the aircraft parking limit lines. With this type of service road, potential conflict between aircraft and vehicles can be an issue. If possible, additional clearance beyond the parking limit lines should be placed to protect aircraft from potential vehicle deviations on the service road. Clear markings are necessary to determine boundaries and to prevent impingement on apron taxiway/taxilane operations. Proper clearance should be defined and maintained from the rear of aircraft to the service road and on to the apron taxiway. Tail-of-stand service roads are beneficial for linear concourse pier terminals when airlines operate gates on both sides of the pier. Head-of-Stand. Many large overseas airports that primarily service widebody aircraft tend to favor head-of-stand service roads located between the face of the terminal building and the aircraft parking and servicing area, because significant portions of operational servicing activity occur at the front of the aircraft. However, the main problem with head-of-stand service roads is clearance height issues for large vehicles that may need to pass under passenger loading bridges. A minimum height clearance of 14 feet (4.2 meters) for the road surface beneath loading bridges and terminal buildings is recommended per IATA standards. A head-of-stand road usually requires the addition of a fixed bridge section that spans over the service road from the terminal to a loading bridge pedestal. This additional distance of the head-of-stand roadway increases the total depth of the aircraft apron. Adequate room for pushback procedures should be planned to allow for aircraft tug maneuverability space that will not interfere with the service road and potentially cause congestion. Conflicts may also exist between these roads and GSE storage beneath the terminal building and apron-level door exits. Between Aircraft Wingtips. These service roads usually occur in conjunction with tail-of-stand service roads and allow smaller size vehicles to pass under the terminal building and/or concourse instead of having to go around the entire face of the building. When roads are placed between aircraft, increased aircraft wingtip separation will be required to protect against aircraft damage in case of vehicle deviation from the service road. Terminal Airside Facilities 115
V.2.6.2 Apron Safety Clearances The required safety clearances on the apron vary greatly depending on the type of operations being conducted. Safety clearances ensure that aircraft can maneuver into/out of gate/stands with- out colliding with other aircraft, terminal facilities, ground service vehicles, and pedestrians or causing damage from jet blast. For example power-in/power-out gates/stands must be much larger and have their respective GSE kept farther away because of the turning radius of the wingtips and the jet blast associated with the power settings required for zero radius turns. Several procedures and enhancements can dramatically increase the effectiveness of these clearances: â¢ Gate/stand lead-in lines â¢ Nose-gear hold lines â¢ Apron safety lines â¢ Dedicated equipment areas â¢ Dedicated service vehicle road â¢ Use of wing-walkers during push-back procedures V.2.6.3 Apron Markings Ground Service Equipment Parking and Staging. The staging and parking is usually limited to the area between the apron safety lineâwhich is painted in redâand either the head-of-stand service road configuration or the terminal building and tail-of-stand service road configuration. Taxiway/Taxilane Centerline. Taxiway and taxilane centerlines provide a visual cue to the pilot to facilitate safe taxiing of the aircraft. The standard for taxiway/taxilane centerline marking is a solid yellow line that is equidistant from either edge of the pavement for taxiways and meets the required safety separation for taxilanes. The width/separation requirements, as well as turning radius requirements, can be found in either FAA AC 150/5300-13 (15) or ICAO Annex 14 (32). Ground Vehicle Roadway Markings. When planning apron spaces, it is essential to delineate where ground vehicles are permitted to operate to prevent unnecessary interference with aircraft operations or passengers. This delineation can be accomplished through the use of ground vehicle markings on the apron pavement. The standards for ground vehicle roadway markings are either solid white lines or a white âzipperâ marking for a low-visibility condition Surface Movement Guidance and Control System (SMGCS) to delineate the roadway edges. The roadway should be wide enough to accommodate the largest vehicle anticipated to be operating at the airport. An SMGCS provides guidance to, and control or regulation of, all aircraft, ground vehicles, and personnel on the movement area of an airport. SMGCS will be applied to all airports where scheduled air carriers are authorized to conduct operations when the visibility is less than 1,200 feet runway visual range. Passenger Walkways. Passenger walkways should be provided on the apron area and if necessary across service roads. The walkways should be painted with white stripes across any active roadway surface. Passenger walkways should be clearly marked and designed to keep movement of passengers clear of hazards and confined within a specific area for security control and safety. Aircraft Maneuvering. From time to time under certain apron conditions and locations, it is necessary for aircraft to perform non-standard maneuvers in the apron area. To assist pilots in completing these maneuvers, special paths for the taxiway/taxilane centerline or gate/ stand lead-in line should be painted on the pavement. An example of this would be the mark- ing of an aircraft push-back line that a tug would follow to ensure adequate clearances are maintained. 116 Airport Passenger Terminal Planning and Design
Aircraft Lead-in Lines. Another form of guidance to a specific aircraft parking position is the use of lead-in lines that help to guide the aircraft into the parking position from the apron taxilane. The exact location and geometry of the lead-in line is based on the type of aircraft that will be using the parking position. Gate parking positions may have multiple lead-in lines for specific aircraft types. Lead-in lines may require arrow heads to indicate the direction to be followed into the stand, nose-gear stop position, and aircraft type, along with the gate designation number or letter. Aircraft NoseâWheel Stop Marks. Whether parking at a remote or contact gate/stand, the aircraft must be properly positioned. An aircraft parked out of position can cause many problems, not the least of which are blocking the flow of aircraft taxiing onto and around the apron, colliding with the terminal building, and being unable to align with the passenger loading bridge. Aircraft noseâwheel stop marks are used to bring the aircraft to a complete halt in the optimal position based on its size and door position. These marks consist of a yellow hash mark perpendicular to and bisecting the gate/stand lead-in centerline, and a corresponding label noting the aircraft type for that mark. Additionally these marks ensure proper alignment of the aircraft for fueling and servicing. Non-Movement Area Boundary. The terminal apron normally has a portion that is part of the non-movement area and a portion that is part of the movement area; therefore, it is important to delineate between these two areas of the apron pavement. A non-movement area boundary marking is located on the boundary between the movement and non-movement area. A non- movement area boundary marking consists of two yellow lines (one solid and one dashed) and will be outlined in black on light colored pavements. The solid line is located on the non-movement area side, while the dashed yellow line is located on the movement area side. This line denotes the point at which aircraft will be transferred over to the ATCT ground control frequency. Aircraft will not proceed past this point without having contacted ground control for permission to taxi onto the taxi movement area surfaces. V.2.7 Aircraft Servicing Ground support services are provided to aircraft while at the terminal gate or remote stand position. For these services to be conducted in a safe and efficient manner, standard locations with ample space for ground equipment placement and operation should be planned when designing the airport gate and apron areas. A staging area should be provided for the necessary GSE around each aircraft parking position. These staging areas provide for pre-positioning of the necessary GSE to provide service to aircraft on arrival at the gate. Proper pre-positioning of GSE around the aircraft parking position will help to minimize the aircraft turnaround time and the potential for aircraft/GSE conflicts. Figure V-9 depicts the typical staging area and servicing units for an aircraft. Areas on the right side of the aircraft nose, forward of the wing and just outside the apron safety lines (the defined aircraft parking envelope, and also called âequipment restraint linesâ), are often used to pre-position GSE. The amount of space required for the GSE staging area is determined by the number of vehicles and equipment needed to perform the specific aircraft services. Aircraft servicing is typically provided by a combination of movable vehicles and equipment and fixed servicing installations. Movable vehicles and equipment usually assemble in GSE storage and/or staging areas, depending on their function and the amount of equipment on site. Fixed servicing installations are commonly located on or under the apron, or on the terminal building contiguous to the aircraft gate. Aircraft gates that contain fixed utility installations benefit from less congestion on the apron from GSE and shorter aircraft servicing times. Possible negatives include some reduction in flexibility to handle different types of aircraft parking configuration and relatively high up-front capital costs. Ultimately it is for the airport owner to weigh the Terminal Airside Facilities 117
comparative costs and benefits, including potential environmental benefit, before determining whether or not to install any fixed servicing systems at airports. The types of ground servicing typically required by aircraft include the following: â¢ Supply of fixed ground power and preconditioned air (during servicing) â¢ Replenishment of potable water â¢ Removal and disposal of toilet waste â¢ Catering/cabin cleaning â¢ Air start services â¢ Fueling â¢ Maintenance of oxygen system 118 Airport Passenger Terminal Planning and Design CATERING MAN 15-163 CATERING M AN 15-163 CATERING M AN 15-163 CATERING MAN 15-163 LAVATORY SERVICING 2150 Liter VASM-300 0 VASM-3000 A L P W AIR CONDITIONING PNEUMATIC PASSENGER LOADING BRIDGE ELECTRICAL GALLEY TRUCK (FIRST POSITION) CONTAINER CARGO LOADER POTABLE WATER VACUUM LAVATORY BAGGAGE HANDLING GALLEY TRUCK (SECOND POSITION) E FUEL TRUCK TOW TRUCK FUEL TRUCK FF CABIN CLEANING SP IJK ST AA L M OD EL 30 7 SPIJKSTAAL MODEL 307 CONVEYOR BELT-1 RHD CHAMP 70S CHAMP 70S TERMINAL BUILDING 25 FT E Q U IP M E N T S TA G IN G A R E A SERVICE ROAD7.5 M B73 7-80 0W B73 7-80 0W 25 FT 7.5 M Source: Landrum & Brown referencing Boeing 737/BBJ Document D6-58325-6, Section 5.0 Terminal Servicing Figure V-9. Typical aircraft servicing equipment.
V.2.7.1 Ground Power To avoid use of the aircraftâs auxiliary power units (APUs) while parked at the gate, ground power units (GPUs) can be utilized in conjunction with preconditioned air systems. Depending on the size of the aircraft, different types of GPUs can be used. Larger aircraft require 400 hertz power supply, which can come from a centralized location or from equipment provided at each gate. GPU equipment at the gate can be either in a mobile cart form or mounted on the passenger loading bridge. Centralized ground power systems generate aircraft-compatible power in one location, from where it is distributed to each gate. Smaller aircraft require 28 volt DC converter GPUs, which cannot be provided from a centralized location. For all types of GPU systems, electrical power transfers through a cable connecting the GPU to the aircraft, and GPUs should be operated only if they are at least 20 feet from aircraft fueling vents and venting points. V.2.7.2 Preconditioned Air When parked at the gate, the aircraft cabin is heated or cooled using either its on-board APU or preconditioned air from ground sources. The preconditioned air (PCA) can be supplied by either mobile or stationary units. Mobile units are typically self-contained, truck-mounted air- conditioning units powered by diesel engines. More prevalent at larger airports are stationary PCA units that are mounted on, or near, the loading bridges and connect to the aircraft by a flexible hose. Stationary systems have the advantage of less ground congestion, and lower emis- sions and energy use. Point-of-use systems have individual air-conditioning units that serve a single gate. Central chiller systems have a single chiller that heats or cools a heat transfer medium (usually water or a glycol/water mix) and then distributes this to air-handling units at each gate. In general, central PCA systems have higher capital costs but lower operations and maintenance costs than point-of-use systems. V.2.7.3 Potable Water Most airport terminal configurations provide for a potable water supply that can be tapped and linked to aircraft. Water cabinets and sources of water from the terminal are typically apron or loading bridge mounted and transfer water via a hose to the aircraft. When potable water supply cannot be replenished from the terminal facility, a water servicing vehicle provides potable water to aircraft. It is important to assure that the source of water is routinely checked for purity and any contamination that may occur. V.2.7.4 Lavatory Cleansing and Waste Removal Servicing involving removal of waste, replenishment of flushing medium (if any), and conveying of waste to disposal systems is generally conducted by ground service vehicles. Potable water service vehicles and lavatory service vehicles must not be parked in the same vicinity when servicing aircraft, or be serviced by the same personnel. Cabin waste originating from domestic and inter- national air carrier flights must be removed and destroyed in conformity with local health codes and airport authority regulations. Usually this destruction involves incineration of the cabin waste in a properly designed facility. Local environmental rules and regulations must be adhered to with respect to emissions and proper disposal of the residue. V.2.7.5 Air Start Pressurized air must be provided for aircraft without APU, and air start systems supply this service. This type of system can be permanently installed similar to other utility systems, or truck- mounted systems can be utilized. The latter is the most common type of equipment currently used. Air requirements for air start range from 120 to 270 pounds per minute at 40 pounds per square inch (psi). Terminal Airside Facilities 119
V.2.7.6 Fueling Airports should seek feedback from airlines and oil companies when planning fuel supply systems at the terminal gate area. Aircraft fueling can be conducted through fuel service vehicles or hydrant systems. The type of system used should be determined in relation to the expected rate of aircraft movements at the airport. In addition, because of the potential for fuel spills and leaks, it is recommended that the aircraft parking apron area should be constructed with portland cement concrete. Whenever possible, a distance of 10 feet should be maintained between fueling equipment and GSE. The provision of adequate aircraft service envelopes is vital for allowing safe maneuvering distances between ground equipment or service vehicles and aircraft at the stand. Truck Fueling. Fuel trucks or tankers carry limited amounts of fuel directly to aircraft, pumping it through connecting hoses into the aircraft, and then return to the fuel farm or fuel distribution point to refill when necessary. For safety purposes, provision of grounding rod locations is required for the fueling truck positions. As already mentioned, the type of fuel system an airport utilizes depends on the level of aircraft activity an airport expects to receive. Fuel trucks typically suit airports with low levels of activity or service smaller aircraft, because adequate apron space is likely to be available and fuel requirements are not too high. At busier airports, fuel trucks are usually not the best option because they tend to cause congestion and take up ramp space. When fuel trucks are present, stop positions for such vehicles should be clearly marked near aircraft stands. Hydrant Fueling. Hydrant systems, a form of underground aircraft fueling, may be preferred over fuel pits and/or mobile fuel trucks because they eliminate the duplication of equipment required for each apron hydrant valve. This type of system does not entirely remove the need for vehicles on the apron because hydrant fueling systems utilize a mobile self-propelled or towed hydrant dispenser unit consisting of a pump filter, meter, and air eliminator. This mobile hydrant unit serves as the connection between the apron hydrant valve and the aircraft fuel service point providing fuel transfer. By comparison, a fuel pit system is equipped with its own hose, reel, filter, and air eliminator at each pit location, thereby eliminating the need for the mobile dispenser unit. Both types of hydrant systems reduce the number and size of ground equipment, aid in decreasing ramp congestion, and enable quick aircraft turnaround times. Hydrant systems lend themselves to modular aircraft parking stands when a single hydrant valve could be utilized for different types of aircraft parking at the stand. A typical planning convention is to design the aircraft stands so that each aircraftâs fueling service point falls within a 30-foot (â¼9-meter) radius of the apron hydrant valve. However, installation of such systems often requires that apron parking stands offer this modular flexibility. The number of hydrants necessary per stand depends on the type of aircraft using the park position. When planning a hydrant fueling system, knowledge of the aircraft configuration is required, because the number and location of hydrant valves on the apron are dependent on the number of gates needing fueling service and the specific aircraft fleet using each parking position. Because hydrant systems are permanently constructed under the apron, any future reconfiguration of the airport terminal buildings or aircraft stands could be limited and/or affected by the location of the hydrant valves. V.2.8 Ground Service Equipment Storage Storage spaces for GSE are defined as the location where equipment utilized in servicing aircraft is positioned when not in use. Airport requirements for GSE storage space and clearances will primarily be determined through consultation with airlines being serviced at the airport. Individual airlines may have varying space requirements depending on the amount of traffic 120 Airport Passenger Terminal Planning and Design
and the nature of their operations. Airport size, terminal configuration, and amount of airline operational activity determine the number of GSE storage areas that should be planned. Storage facilities should be designed of adequate size to accommodate all equipment in regular use in each and every sector of the airport and should allow for speedy and convenient access to the apron. When possible, the major GSE storage area should be located in a separate area within close proximity to the aircraft apron. A remote location will help to avoid interfering with regular apron operations but should not be so far away that it takes excessive time to reach the aircraft parking positions. There is also a need to have some GSE storage adjacent to the aircraft parking apron to be readily available when it is required, ensuring an efficient operation. The storage areas, which should be well delineated, should be properly sized to accommodate all equipment used on a regular basis to serve the parked aircraft in that section of the apron area. V.2.9 Apron Lighting Various degrees of illumination are required for outdoor apron areas during darkness and low-visibility conditions, and the section of apron containing aircraft stands requires a relatively high level of illumination compared to other areas of the airport. Apron area lighting ensures safe, secure, and efficient airport operations by increasing general visibility in this critical area. Apron lighting enhances airport security by enabling observation of passenger and employee activity, identification of personnel on and near aircraft stands, and detection of possible unauthorized persons. Adequate apron lighting is also important to ensure the effective operation of CCTV cameras. If the primary purpose of lighting a particular part of the apron is for security and safety purposes, the system should be backed up by an emergency power supply. Specific criteria should be considered when designing or modifying apron area lighting. These criteria include dimensions of the apron(s), arrangement of aircraft stands, specific types of aircraft using apron parking positions, taxiway arrangements and traffic schemes, adjacent areas and buildings (i.e., control towers), and location/status of runway and helicopter landing areas. The light angle and shielding of glare should be considered to assure there is not impact on aircraft landing, takeoff, or taxiing operations. Maintenance expense and access to replace lights may also be a factor in reviewing potential apron lighting options. Lights should be placed so they will be easily accessible without using special equipment. If access to lights is difficult, it may be more economical to change lamps on a group replacement basis. The cost of replacing lamps in high-mast lighting can be significant, so long-life lamps should be used. Aprons are often illuminated from lights that are either attached, or adjacent, to the terminal building or concourse face. Night-time illumination levels should be a minimum of 20 foot-candles (215 lux) adjacent to the terminal and a minimum of 2 foot-candles (â¼22 lux) at the tail of aircraft. ICAO Annex 14 (32) recommends average horizontal luminance on aircraft stands of 20 lux with a uniformity ratio of not more than 4:1 and, for other apron areas, 50% of the average luminance on aircraft stands with a uniformity ratio of not more than 4:1. The area between aircraft stands and apron limits should be illuminated to an average horizontal luminance of 10 lux, and, if high-mounted headlights do not light the area adequately, glare-free lighting of the street-lighting type should be utilized. Height restrictions for apron lighting may also need to be in place, depending on how close the runway is to the terminal or concourse. In general, ICAO recommends average vertical luminance should be 20 lux at a height of 2 meters above the apron in all relevant directions. The FAA advises that mounted floodlights, sometimes referred to as high-mast lightingâand a commonly preferred type of apron lighting, Terminal Airside Facilities 121
should be placed at a height of 25 to 50 feet (8 to 15 meters) with maximum spacing of 200 feet (60 meters). FAA regulations require airports to be responsible for ensuring that all lighting on the airport, including that for aprons, is placed at a level that is adequately adjusted and shielded to prevent interference with air traffic control and aircraft operations, without reduc- ing necessary illumination of critical areas. To minimize direct and indirect glare, mounting heights for floodlights should be at least two times the maximum eye level of the cockpit of aircraft regularly using the airport. The location and height of light masts should be placed to keep inconvenience to ground personnel due to glare at a minimum but to provide desired illumination levels. Additionally, uniform luminance of entire aircraft stands should be present, compared to individual direction of lighting toward aircraft. Even lighting levels can be accomplished by arranging and aiming lights in two or more directions toward aircraft stands, and minimizing potential shadow areas. In areas where unavoidable shadows occur, supplementary lighting may be required. On taxiways adjacent to aircraft stands, a low degree of luminance should be utilized for providing a gradual transition to higher luminance on aircraft stands. Light distribution should be such that all colors used for aircraft markings can be correctly identified, if necessary, through adaptation by the use of screens. Light sources most suitable for identifying routine servicing and surface markings are incandescent halogen and high-pressure gas discharge lamps. Because discharge lamps produce color shifting, a three-phase electrical supply system should be utilized to avoid this strobo- scopic effect. Colors resulting from discharge lamps must be checked during daylight and artificial lighting situations to ensure correct color identification. High-pressure sodium or mercury halide lamps should be used when adjusting color schemes used for surface and obstruc- tion markings. V.2.10 Apron Snow Removal During snow removal operations on the airfield, the potential exists for interaction between ground vehicles and aircraft, whether taking place in the movement or non-movement areas. For this reason it is important to coordinate all snow removal operations with the ATCT and determine which activity will have the right-of-way throughout the airport. In some cases the snow equipment will have the right-of-way in order to clear a pavement area to allow aircraft operations to move in a more safe and efficient manner. V.2.10.1 Snow Haul Route When planning for snow removal operations on and around the terminal apron area, it is important to provide dedicated routes for the collection and hauling of snow from the apron area. Provision of dedicated routes can usually be accomplished by using the existing airside service roadway network; however, it may also require a secondary roadway network within the terminal ramp area to efficiently conduct the snow removal operation. V.2.10.2 Snow Melter Operations Airports that utilize snow-melting equipment (mobile or in-ground) within the terminal ramp area should identify an area where they will position this equipment such that it does not affect aircraft operations or gate positions. The terminal ramp area should be graded such that any snow-melting operations that take place do not cause ponding and eventual re-freezing of water in the ramp area. Adequate drainage must be provided in the location where snow melting is taking place. Local and U.S. Environmental Protection Agency environmental regulations for the treatment of contaminated groundwater must also be considered when deciding to use snow melters in the terminal ramp area. 122 Airport Passenger Terminal Planning and Design
V.3 Aircraft Gate Requirements V.3.1 Aircraft Gate Types When planning an airport apron layout, an important aspect to consider is passenger loading and unloading between the terminal building and aircraft. The decision on which type of gate to use will depend largely on the level of aircraft traffic that is to be accommodated, the terminal layout, and local airport conditions. Aircraft gates are either considered contact gates or remote gates. Contact gates are either in physical contact with the terminal through the use of a passenger loading bridge or in enough proximity to the terminal to allow passengers to walk to the aircraft. Remote gates (or stands) are far enough from the terminal to require some type of bus or transporter for passengers. The terms âremote gateâ and âstandâ are synonymous, with the term remote gate being more commonly used in the United States. Airports with lower levels of air service, or service by regional aircraft, have tended to use apron ground loading. Larger airports with higher commercial aircraft activity by mainline aircraft typically employ passenger loading bridges. Some of these differences have been disappearing as airlines operating regional aircraft request loading bridges to provide the same level of passenger service as the mainline equipment they replace. V.3.1.1 Contact Gates When planning contact gates, consideration must be given to providing sufficient space for GSE operations and staging (See Sections V.2.6.3 and V.2.7.6). Aircraft must be parked so as to allow safe operation of passenger loading bridges for the range of aircraft that are expected to be using each gate. If passengers are to walk to their aircraft, well-marked paths must be maintained at a safe distance from ground equipment and engines of parked aircraft. Loading Bridges. Passenger loading bridges are positioned to bring passengers to left-side aircraft boarding doors, with the bridges located forward of the aircraft wing. Many aircraft types support passenger boarding through only a left-side door. When compared to conventional air stairs and mobile lounges, loading bridges tend to reduce passenger disembark/embark times, resulting in 25% faster movement of passengers. They also improve passenger and staff safety, passenger experience, and disabled access between the aircraft and terminal building in comparison to ground loading of passengers. General loading bridge requirements include the ability to communicate with passengers queuing between the gate and aircraft in case of an emergency, bridge emergency escape stairs, backup systems, fire suppression systems, emergency lighting, and clear maneuvering range markings on the airport apron. Also, maximum gradients must comply with ADA requirements of 1:12, while a 1:10 slope is recommended by IATA and ICAO. In the United States, the National Fire Protection Association requires that no transparent or translucent walls, surfaces, or windows be in passenger loading bridges, except for in the cab area and on the ramp service door. Primary factors to consider when planning passenger loading bridges include aircraft door sill heights and door positions. The type of passenger loading bridge and its length are determined based on apron dimensions, aircraft wing span, aircraft door locations, fixed aircraft services, adjacent aircraft positions, and economics. Two primary types of loading bridges and slight vari- ations of these tend to be utilized: apron drive bridges and fixed bridges. Apron Drive Bridges. Apron drive bridges provide the most flexibility in serving a wide range of aircraft types. Apron drive bridges consist of a rotunda, two or three telescoping tunnels, and a rotating cab that docks to the aircraft as depicted in Figure V-10. Depending on the size of the Terminal Airside Facilities 123
apron and aircraft parking locations, a fixed link section may be installed between the terminal and the rotunda. The rotunda is a fixed unit on the aircraft apron, and the main support mechanism for the loading bridge. Apron drive bridges move on three axes: vertically about a pivot point on the rotunda, laterally through telescopic section movement, and on an arc rotating about the bridge rotunda. The cab that docks with the aircraft also rotates and can either be non-leveling or self-leveling. The self-leveling cab is generally recommended because it is safer for passengers and staff when telescopic sections are on maximum gradient. However, it produces less effective slope length, which may be a consideration when aircraft must be parked very close to the terminal. For apron drive loading bridges, the maximum extension and minimum retraction limits (operational range) and maximum passenger loading bridge slope requirements must be examined and approved in overall apron and gate planning. The three-tunnel bridge is generally recommended for use when the range of aircraft height differential varies the most. The apron drive bridgeâs operation should not interfere with other aircraft or GSE movements. If a fixed section is used from the terminal building to the apron drive pedestal in a âhead of standâ service road configuration, as frequently done outside of the United States, then this fixed bridge section must be positioned to allow the highest GSE vehicle anticipated to use the service road that passes beneath. Most airports prohibit vehicle traffic or parked equipment under the movable portion of an apron drive bridge and therefore the apron should be striped as a no parking/ no traffic area. The floor elevation of the terminal, or concourse, along with the floor levels of the fixed section, the rotunda, and the tunnel sections of the loading bridge itself, must provide a gradual transition for passengers walking to and from the aircraft without any steep slopes. In the United States, no ramped surface in the passengers path to and from the aircraft to the building should exceed the ADA maximum slope requirements of 1:12. A specific category of an apron drive loading bridge, called the âover-the-wing apron drive bridge,â docks with the rear door of aircraft. This configuration permits two or three loading bridges to service a single aircraft. Figure V-11 depicts an over-the-wing bridge servicing the upper-deck passenger doorway of an A380. The downside to dual- and triple-service apron drive bridges 124 Airport Passenger Terminal Planning and Design Rotunda Tunnel Drive Column & Wheel Bogey Service Access Rotating Cab Source: Landrum & Brown Figure V-10. Apron drive bridge.
includes restricted GSE movement around aircraft, more equipment in the gate area, and less general flexibility than single-service apron bridges. Also, utilization of dual- and triple-service loading bridges should not interfere with adjacent aircraft parking positions, and special striping for bridge movement should be present. Fixed Bridges. Airports with gates servicing one type of aircraft, or aircraft of similar sizes and door sill heights, may opt for fixed loading bridges. As depicted in Figure V-12, fixed bridges typically consist of a fixed link from the terminal to a pedestal, a two-tunnel telescoping section, and a cab with limited rotation as compared to an apron drive bridge. Fixed bridges are more economical than apron drive bridges, but less flexible in accommodating different types of aircraft with wide-ranging door sill heights. Fixed bridges move on two axes: vertically about a pivot point at the end of the telescoping section, and laterally through telescopic section movement. It is possible to service aircraft of separate size categories via this type of loading bridge, but doing so can result in a steep tunnel for multiple aircraft lead-in centerlines. Also, fixed bridges require the aircraft to be stopped more accurately than is required for apron drive bridges, because cab movement is limited. However, Terminal Airside Facilities 125 Source: Landrum & Brown Figure V-11. Over-the-wing bridge. Fixed Sloped Tunnel Service Access Sloped Cab Fixed Pedestal Rotunda Source: Landrum & Brown Figure V-12. Fixed bridge.
less protection of the apron area is necessary compared to the apron drive bridge because the tunnel section moves over less apron space with the fixed bridge. Apron-Level or Ground-Loaded Gates. Ground-loaded gates are typically used for smaller regional aircraft but may be used for mainline aircraft when traffic volume or terminal design does not justify a loading bridge. Planning for passenger walking routes between the terminal and aircraft should involve determining the shortest possible route and maintaining free movement of aircraft, vehicles, and passengers while avoiding conflict between them. Pathways for passengers must be clearly marked, free of obstacles, and closely monitored for safe and secure movement between aircraft and the terminal. In an effort to improve passenger service and provide some of the amenities of mainline aircraft boarding for regional aircraft, various passenger boarding assistance devices have been developed that provide weather protection for apron loading. Some of these devices include ramps that substitute for the aircraftâs stairs, and separate wheelchair lifts. When planning for using weather protection devices, the method of movement and materials must be considered to minimize conflicts with aircraft parking and push/power-out movements. Apron drainage must also be considered. V.3.1.2 Remote Gates/Hardstands The alternative to contact gates is remote gates or hardstands. These remote parking positions for commercial aircraft can be located close to the terminal, but further than walking distance, or quite far away depending on the available space. Remote gates can have some benefits (depending on configuration) including the following: â¢ Potentially allow for a greater number of gates/stands on a finite amount of apron space â¢ Can be configured to allow taxi-in/taxi-out operations â¢ Allow for less constrained ground service vehicle operations â¢ Can serve a wide range of aircraft gauge within a single gate and accommodate multiple aircraft mixes on the remote apron â¢ Can require lower infrastructure cost than contact gates While remote gates are initially less expensive to develop, their operating costs can exceed those of contact gates because of the need to operate a system of busing or other forms of transportation to take passengers to and from the terminal. Other disadvantages would include possible conflict between aircraft flows and buses on and around the apron, increased passenger enplaning and deplaning times, and a lower level of passenger service. There are two basic types of vehicles for transporting passengers between the terminal and remotely parked aircraft: â¢ Transporters (or mobile lounges): This special type of airport equipment is designed to ele- vate vertically, connect with a terminal dock and/or aircraft, and drive between each location. Passengers typically walk directly into the transporter on the same level as the terminal or aircraft. One early type of mobile lounge used an elevating gangplank with 6 to 10 feet (1.8 to 3 meters) of extension, which adjusted to various aircraft sill heights. Most transporters in current use and manufacture have an elevating passenger compartment and loading bridgeâtype coupling to allow compatibility for proper aircraft positioning. This type of equipment adds to the number of vehicles operating on the apron and may require construction of larger service roads. Also, more than one mobile lounge may be required to accommodate all passengers on a flight and increases the amount of time required for passenger processing. Although a few airports were designed around transporters (Washington Dulles being the best known example), transporters are more typically used for overflow remote gates. 126 Airport Passenger Terminal Planning and Design
â¢ Buses: Around the world airside buses are the most common means of transporting passengers to and from aircraft parked at remote gates. The size of the bus can be matched with the type of aircraft and range in capacity from less than 50 to approximately 130 passengers. Specialized apron buses are designed with low floor height, wide doors, and minimum seating around the cabin to accommodate a large number of passengers, as well as disabled passengers. Location for loading and unloading passengers from buses should be as close as possible to the terminal building and airside waiting area to limit distance required for passenger walking. It is generally recommended that arrival and departure flows should be separated with separate bus loading/ unloading areas. There are two basic ways to board or disembark at remote gates/hardstands: â¢ Mobile stairs: Mobile stairs must be provided for most aircraft at remote gates. These stairs can be covered or uncovered, and are pushed or driven to aircraft and set at door level. Fitting mobile stairs with canopies will improve customer service standards. Some types of aircraft (primarily regional aircraft) contain integral steps, which are only accessible when the crew releases or opens an aircraft door allowing passengers to board or disembark. When stairs are the only method that passengers can take to or from the aircraft, wheelchair lift devices must be provided allowing passengers with mobility impairments to board. â¢ Permanent remote gates: When hardstands are used on a regular basis, some airports have developed permanent remote gates that include a covered bus loading/unloading curb, a ramp system, and a loading bridge. This allows a faster and easier boarding and disembarking process with the weather protection of a contact gate. An example is the West Pad gates at Los Angeles International Airport as depicted in Figure V-13. V.3.2 Aircraft Push-back Zones When planning the terminal ramp areas, it is important to remember that aircraft will require space to push back from their respective gate. This space can be provided by either a dedicated area for push-backs, multiple parallel taxilanes so that the aircraft being pushed back can use one of the taxilanes, or a combination of a dedicated push-back lane with multiple parallel taxilanes (usually reserved for larger airports with heavy peak congestion periods). The push-back zone Terminal Airside Facilities 127 Courtesy of: Â©2009 Microsoft Corporation, Â©2008 NAVTEQ, and Â©2008 Pictometry International Corp. Figure V-13. West Pad gates of Los Angeles International Airport.
depth should be adequate to position an aircraft such that it can power-out and not cause damage due to excessive jet blast. V.3.3 Power-out and Power-back Operations The two ways in which an aircraft can leave a gate position under its own power are referred to as power-out and power-back operations. The power-back operation is when the aircraft uses its thrust reversers to power straight back from the gate position. This type of operation should not be considered as part of normal operating procedure because of the concern of foreign object damage kick-up into the engine intake and jet blast damage to ground personnel and equipment. In addition, there is additional fuel burn associated with the power-out operation that is expensive. The power-out operation is depicted in Figure V-14. This operation is accomplished by the aircraft moving forward slightly under its own power and turning to exit the gate position. This operation is normally only acceptable at smaller, less congested airports because of the large amount of ramp space required and the inability to use a passenger loading bridge. In the United States this power-out operation is typically conducted by smaller commuter aircraft that are located at apron parking positions; passengers typically load and unload to and from the apron level through the aircraftâs built-in passenger stairway. These types of power-out and power-back operations can generate the potential for significant jet blast on surrounding areas, which should be analyzed and considered during the detailed planning phase. V.3.4 Taxi-in and Push-back Operations The most prevalent aircraft parking operation at U.S. terminals is the taxi-in/push-back procedure associated with various types of loading bridges at the terminal or concourse. In this 128 Airport Passenger Terminal Planning and Design Ground Service Roadway Taxi-in Operation Taxilane Power-out Operation Source: Landrum & Brown Figure V-14. Taxi-in and power-out operation.
operation the pilot brings the aircraft in under its own power following the lead-in line associated with each gate position. During this maneuver the pilot is typically assisted by wing walkers on the apron to ensure that the aircraft is clear of any obstacles out on the ramp. The pilot may also be assisted by a visual docking guidance system, which is described in more detail in Section V.2.3.1. For the aircraft to leave the gate, a tug either is brought into position or has already been positioned before the aircraftâs arrival and is connected to the aircraftâs nose gear. The tug then performs a push-back operation by maneuvering the aircraft out of the gate area to a position out on the apron or taxilane where the pilot can safely power up its engine(s) to proceed under its own power. Figure V-15 depicts the taxi-in and push-back operations. V.3.5 Tug-in Operations In areas of confined terminal apron space and the need to maximize the number of gate positions, an operation known as tug-in should be considered. This practice is seen as preventative in order to eliminate the potential for aircraft collisions and jet blast in such tight operating areas. When planning for such operations, it is important to remember the time in which aircraft are waiting in the movement areas for their respective tug and the effect these stationary aircraft might have on the movement of other aircraft. Adequate vertical and horizontal clearances must be maintained between all aircraft surfaces during this operation. V.3.6 Apron Circulation When planning for apron circulation, a number of factors must be considered such as the type of terminal facility the apron area serves, the number of gates, the number of operations, the type and size of the aircraft operating on the ramp, and the type of vehicles servicing the aircraft. For standard linear or satellite terminals, a flow-through taxiway/taxilane would be the preferred form of circulation into, out of, and through the apron area. For pier fingerâstyle terminals or Terminal Airside Facilities 129 Taxi-in Operation Ground Service Roadway Taxilane Push-back Operation Source: Landrum & Brown Figure V-15. Taxi-in & push-back operations.
those terminals with apron areas having only one way in and out, dual parallel taxilanes are the recommended form of circulation when more than six or eight gates are served. As stated previously, dual taxilanes allow for uninterrupted access to all gates served by the apron. V.3.7 Jet Blast Effects and Mitigation In certain terminal configurations, especially when the aircraft are operating under their own power (taxi-in/out), it is important to consider the potential effects of aircraft jet blast and propeller wash. When planning airside facilities, it is important to consult the specific Airplane Characteristics for Airport Planning manuals for the aircraft that will be using the airport. These manuals are produced by the aircraft manufacturers and are available on their website in most instances. Using these manuals, it can be determined what areas will be affected by the aircraft jet blast. Once these areas have been determined, blast fences, or other types of jet blast protection, can be considered as a means of mitigating potential damage. It is also important to consider the effects of jet blast on the terminal building windows and faÃ§ade in those areas where a blast fence cannot be installed. These surface areas must be able to withstand jet blast velocities if power-out use is anticipated. Section V.2.5 contains expanded information relevant to blast fences and jet blast protection. V.3.8 Forecasting Gate Demand Using Design Day Flight Schedules If a DDFS has been developed for a forecast year (or annual activity level), a relatively detailed study of gate requirements can be performed. Typically a DDFS is developed when airside simulation modeling is done for an airport. See Section IV.4, Peak Hour Demand Analysis, for additional information about using and creating flight schedules. In many cases a DDFS is produced as separate lists of flight arrival and departure records in a spreadsheet format. For it to be used for gate requirements analyses, arrivals and departures must be matched up. This matched schedule can then be analyzed in a spreadsheet or by various proprietary models to determine the number of gates required during the course of the day. Two types of charts are used to display gate requirements information: â¢ Histograms or bar charts that show the number of gates used by time of day â¢ Gantt or ârampâ charts that show how each gate gets used by time of day Both types of charts can use colored bars to indicate different airlines or aircraft types in the analysis. While this type of analysis can be very detailed, it is dependent on the assumptions used to add flights by specific airlines or aircraft types over time. Figure V-16 depicts an example histogram or bar chart showing the number of gates needed by time of day. This analysis was prepared using a spreadsheet model that analyzed a matched DDFS. The analysis summary shows gate requirements by aircraft type (in colors) and time of day. An alternative to using a spreadsheet model is to create a Gantt or ramp chart of gate usage that shows, by time of day, which flights were assigned to which gates. These charts can be drawn by hand or created using special purpose (often proprietary) software. This special purpose software also can determine which flight goes on which gate based on a database or âruleâ base that describes which airline can use which gates, aircraft gate sizes, and whether the gate can accept international flights. The chart shown in Figure V-17 depicts an example of a ramp chart developed using special purpose software. Figure V-17 shows gates (vertically) and hours of day (horizontally), and each color represents a specific airline. Ramp charts can be a useful method to show a high volume of specific gate use information in an easy-to-read format. Both types of analysis consider both the time the gate is actually occupied by an aircraft and a âbufferâ time when the gate is unoccupied. This buffer time allows airlines to reposition ground equipment for the next aircraft. In addition, the buffer time accounts for the variability between scheduled and actual times that normally occurs in day-to-day operations. A buffer time of 130 Airport Passenger Terminal Planning and Design
15 to 20 minutes is normally used. Longer buffer times may be used at international terminals, where on-time performance is likely to be more variable. Shorter buffer times may be used in day-to-day operations on a domestic terminal. V.3.9 Forecasting Gate Demand Without Using Design Day Flight Schedules When a DDFS is not available, two other approaches can be used. These approaches also allow the terminal planner to easily do âwhat ifâ sensitivity checks on basic assumptions, including those that may underlie a DDFS. V.3.9.1 Average Passengers per Gate Approach The first approach (example shown in Table V-5) uses the current ratio of annual passengers per gate, adjusted for forecast changes in fleet mix and annual load factors. This methodology assumes that the pattern of gate utilization will remain relatively stable over the forecast period. The changes in passengers per gate would be due to changes in enplanements per departure (due to fleet seating capacity and/or passenger load factors), as opposed to increasing (or decreasing) numbers of departures per gate. The basis for the existing factor is the number of gates in use. This number may be less than the number of gates available at an airport. In rare cases of over-crowded terminals, aircraft may be double parked at existing gates, so it is important to determine the true demand for active Terminal Airside Facilities 131 Source: Hirsh Associates Figure V-16. Example of a gate requirements chart from a spreadsheet.
132 Airport Passenger Terminal Planning and Design aircraft parking. From the existing passenger activity and annual departures, the current ratios of annual passengers per gate and enplanements per departure are calculated. Similar calculations can be based on total annual passengers, airline operations, or a combination of these, depending on how the airport keeps its statistics and develops its forecasts. Forecasts for annual enplanements and departures (or total passengers and operations) are forecast separately. As noted in Chapter IV, annual departures are typically forecast based on assumptions for fleet size and load factors, which are applied to the passenger forecasts. Source: Landrum & Brown Figure V-17. Example of a ramp chart. B C D E F denalpnEdenalpnElaunnA Enplaned Annual # of Passengers Passengers Year Passengers Departures Gates per Gate per Dept. 2006 3,462,920 62,670 36 96,200 55 2007 3,336,027 63,808 36 92,700 52 2008 3,399,000 63,000 36 94,400 54 2010 4,429,000 79,500 45 97,500 56 2015 5,287,000 91,500 52 101,100 58 2020 6,240,000 106,500 61 102,500 59 2025 7,096,000 121,000 69 102,600 59 1/ EnPax per Gate = EnPax per Gate Prev. Year x EnPax per Dept. Current Year / EnPax per Dept. Prev. Year 2/ Gates = Annual EnPax / EnPax per Gate A F O R E C A S T Equals Multiply Ratio Source: Hirsh Associates Table V-5. Enplanement per gate approach.
The ratio of enplanements/gate for each forecast year is calculated by multiplying the current (2008 in this example) factor (Column E) by the percentage increase in enplanements/departure. For example, enplanements per departure increases from 54 in 2008 (actual) (Column F) to 56 in 2010 (forecast), thus the factor would increase from 94,400 enplanements/gate (2008 data when 36 gates were in use) to 97,500 for 2010, and 102,600 enplanements/gate by the end of the forecast period without any further increase in the number of daily departures per gate. Future gate requirements are then estimated by dividing annual forecast passengers (Column B) by the estimated passengers per gate factor for that forecast period. For example, in 2010, 4,429,000 enplanements (Column B) divided by 97,500 enplanements/gate (Column E) results in a demand for 45 gates (Column D). This approach results in a forecast demand for 69 gates by the end of the forecast period. The future gate requirements determined in the model are in bold and are driven by the growth rates of enplaned passengers per departure. The growth in enplanements per departure is used to determine the enplanements per gate for forecast planning years. The number of required gates in those years is then determined by dividing the annual enplaned passengers by the enplaned passengers per gate values. The values listed in the table show relatively small increases in the passengers/gate and passengers/departure ratios over the forecast range. Terminal Airside Facilities 133 For additional insight and practical help in performing the determinations and methods described in this section, go to the Gate Demand model provided in Volume 2: Spreadsheet Models and Userâs Guide. This model takes the user through the steps to estimate the future gate requirements using the two methods described in Tables V-5 and V-6. V.3.9.2 Departures per Gate Approach The first methodology has as an underlying basis that the pattern of service is basically stable. While this may be true at many airports and for some airlines at a given airport, it is often likely that gate utilization will change to some extent for other airlines. With a forecast reduction in mainline jets, for example, additional flights by regional aircraft may be scheduled as demand grows. Similarly, airlines may add flights to their hubs from spoke cities, which typically results in higher average gate utilization. However, if an airport attracts service by new entrant airlines, these carriers are often likely to initially follow scheduling patterns similar to existing carriers. This could result, for example, in a demand for more gates during the morning departure peak, and a reduction in average daily gate utilization. For the departures per gate approach (example shown in Table V-6), the ratio of annual departures/gate for each forecast year is calculated by multiplying the current (2008) factor by the percentage change in assumed daily departures/gate. In this example, it was assumed that average daily gate utilization would increase from 5.0 departures/gate in 2008, to 5.2 departures/gate by 2010, and gradually increase to 6.5 departures/gate by 2025. Thus, the annual gate utilization factor would increase from 1,750 annual departures/gate (2008) to 2,290 by 2025. The future gate requirements determined in the model are in bold and are driven by the growth rates of daily departures per gate. The growth in daily departures per gate is used to determine the Annual departures per gate for forecast planning years. The number of required gates in those years is then determined by dividing the annual departures by the annual depar- tures per gate values.
Future gate requirements are estimated by dividing annual forecast departures (Column C) by the estimated departures per gate factor (Column F) for that forecast period. For example, in 2010, 79,500 departures (Column C) divided by 1,820 departures/gate (Column E) results in a demand for 44 gates (Column D). For most airports that assume increasing gate utilization, the departures per gate approach will result in a demand for fewer gates than the annual passengers per gate approach. V.3.9.3 Remain Overnight Aircraft Parking At many airports, the pattern of airline service results in more aircraft being on the ground overnight than the number of active gates. This is more pronounced at âspoke airportsâ when an airline may have, for example, hourly service to its hub for the first few hours of the day. Because it may take until mid-morning before aircraft begin to arrive, a single gate may accommodate two to three aircraft departures for which the aircraft must be parked overnight. Because the cost of building a terminal for contact gates is significant, these remain overnight (RON) aircraft are usually parked remotely, or in some cases double parked on contact gates if the apron geometry allows. If RON aircraft are parked remotely, they are typically towed to a contact gate for departure and towed off a contact gate to the RON parking area after the evening arrival. Estimating the number of RON positions for planning should take into account the airportâs air service pattern, the forecasts for cities to be served in the future, whether these are hub or direct destination flights, and the relative utilization of gates. The location of the RON parking apron should consider the distance from the terminal for towing aircraft and the route to be followed to minimize the effect on other aircraft movements. V.3.10 Gate Equivalents Airport comparisons are also frequently made on the basis of passengers per gate or terminal area per gate, but these lack a consistent definition of the term âgate.â To standardize the definition of âgateâ when evaluating aircraft utilization and requirements, two metrics have been developed: narrowbody equivalent gate (NBEG) and equivalent aircraft (EQA). V.3.10.1 Narrowbody Equivalent Gate This metric is used to normalize the apron frontage demand and capacity to that of a typical narrowbody aircraft gate (see Table V-7). The amount of space each aircraft requires is based on the maximum wingspan of aircraft in its respective aircraft group. FAA ADGs used to define runway/ taxiway dimensional criteria have been used to classify the aircraft as in Table V-7. 134 Airport Passenger Terminal Planning and Design B C D E F liaDlaunnAlaunnA y Enplaned Annual # of Departures Departures Year Passengers Departures Gates per Gate per Gate 2006 3,462,920 62,670 36 1,740 5.0 2007 3,336,027 63,808 36 1,770 5.1 2008 3,399,000 63,000 36 1,750 5.0 2010 4,429,000 79,500 44 1,820 5.2 2015 5,287,000 91,500 47 1,930 5.5 2020 6,240,000 106,500 50 2,110 6.0 2025 7,096,000 121,000 53 2,290 6.5 1/ Ann. Dept. Gate = Ann, Dept.per Gate Prev. Year x Dly Dept.per Gate Current Year / Dly Dept. per Gate Prev. Year 2/ Gates = Annual Departures / Annual Departures per Gate A F O R E C A S T Ratio Multiply Equals Source: Hirsh Associates Table V-6. Departure per gate approach.
Group IIIa has been added to more accurately reflect the B757, which has a wingspan wider than Group III but substantially less than a typical Group IV aircraft. In developing terminal facilities requirements, the apron frontage of the terminal, as expressed in NBEG, is a good determinant for some facilities, such as secure circulation. Terminal concepts also can be more easily compared by normalizing different gate mixes. Figure V-18 depicts NBEG comparison. V.3.10.2 Equivalent Aircraft The concept of EQA is similar to that of NBEG, which is a way to look at the capacity of a gate. EQA, however, normalizes each gate based on the seating capacity of the aircraft that can be accommodated. The EQA measure was originally developed in the early- to mid-1970s as a technique for sizing terminal facilities and comes from The Apron & Terminal Building Planning Manual (2). When the manual was developed, the majority of jet aircraft had 80 to 110 seats, thus the EQA measure centered on the 80- to 110-seat range. Smaller aircraft had an EQA of 0.6 and larger aircraft fell into seating ranges with the center of the range determining the EQA of that range. One hundred seats was equal to 1.0 EQA, aircraft in the 211- to 280-seat range had an EQA of 2.4, and so forth. In considering the modern fleet mix of regional and jet aircraft, and in order to have some relationship with the physical parameters associated with the NBEG, the basis of EQA has been revised from the 1970s definition. The current EQA is also a Group III narrowbody jet. Most of the larger aircraft in this class typically have 140 to 150 seats. Therefore, the basis of 1.0 EQA is 145 seats. As with the concept of NBEG, smaller aircraft may use a gate, but the EQA capacity is based on the largest aircraft and seating configuration typically in use. (See Table V-8). While most terminal facility requirements are a function of peak hour passenger volumes, some airline facilities are more closely related to the capacity of the aircraft. For example, while the total number of baggage carts required for a flight are a function of peak hour passengers Terminal Airside Facilities 135 FAA Airplane Maximum Typical NBEG Design Group Wingspan Aircraft Index Feet Meters I. Small Regional 49 15 Metro 0.4 II. Medium Regional 79 24 SF340/CRJ 0.7 III. Narrowbody/Lrg. Regional 118 36 A320/B737/DHC8/E175 1.0 IIIa. B757(winglets) 135 41 B757 1.1 IV. Widebody 171 52 B767/MD11 1.4 V. Jumbo 214 65 B747,777,787/A330,340 1.8 VI. Super Jumbo 262 80 A380/B747-8 2.2 Source: Hirsh Associates Table V-7. Narrowbody equivalent gate index. For additional insight and practical help in performing the determinations and methods described in this section, go to the Gate Demand model provided in Volume 2: Spreadsheet Models and Userâs Guide. This part of the model shows how the equivalent NBEG or EQA are determined using the index factors illustrated in Tables V-6 and V-7 through a cumulative summation.
136 Airport Passenger Terminal Planning and Design A38 0-8 00 GP A38 0-8 00 GP B77 7-3 00 B77 7-3 00 B76 7-3 00 B76 7-3 00 B75 7-20 0 B75 7-20 0 Code A Code A CRJ- 200 CRJ -200 Feet Meters 15 24 36 41 52 65 80 Source: Hirsh Associates and Landrum & Brown Figure V-18. Narrowbody equivalent gate comparison. FAA Airplane Typical Typical EQA Design Group Seats Aircraft Index I. Small Regional 25 Metro 0.2 II. Medium Regional 50 SF340/CRJ 0.4 III. Large Regional 75 DHC8/E175 0.5 III. Narrowbody 145 A320/B737/MD80 1.0 IIIa. B757 (winglets) 185 B757 1.3 IV. Widebody 280 B767/MD11 1.9 V. Jumbo 400 B747,777,787/A330,340 2.8 VI. Super Jumbo 525 A380/B747-8 3.6 Note: With updated values based on todayâs equivalent aircraft (Group III). Source: The Apron & Terminal Building Planning Manual, for U.S. Department of Transportation FAA, by the Ralph M. Parsons Company, July 1975. Table V-8. Equivalent aircraft index.
(and their bags), the number of carts staged at any one time are generally based on the size of the aircraft. Thus, the EQA capacity of the terminal can represent a better indicator of demand for these facilities. The number of seats in each ADG can vary considerably from the basic definitions. For example, larger regional jets in Group III can be in the 100- to 110-seat range, while a Group III A321 narrowbody can have over 180 seats. Similarly, as fuel economy and range become more important, most widebody aircraft are being designed with wider wingspans in Group V but may have seating capacities in the low 200s. For a given airport, it may be appropriate to modify the EQA metrics to better match the fleet mix expected when using EQA to determine some terminal facilities. Terminal Airside Facilities 137