Guidebook on General Aviation Facility Planning (2014)

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125 A P P E N D I X B How To Size An Apron Parking Area The appendix explains how to size an apron parking area and the reasoning behind starting with a Group I tie-down position and what size it should be. Tie-Down Layout FAA Advisory Circular 150/5300-13A (AC-13A), Appendix 5 provides guidance for laying out tie-down parking positions for GA aircraft. AC-13A suggests that the tie-down size should be based on the largest aircraft that will be tied down. A sampling of tie-down sizes was taken from the airports used in the Data Collection phase of developing this Guidebook. The sizes ranged from 24′ × 17′ to 40′ × 20′. To provide a similar sized tie-down and meet the new AC guidelines, it was decided that an aircraft that provided a similar sized tie-down should be chosen to configure a “base” tie-down layout. Using the guidelines in AC-13A and a Beech Baron 58, a tie-down position of 38′ × 20′ was developed. Tie-Down Parking Areas Notes: • For this Guidebook, a Tie-down position and a Parking position are NOT the same. A Tie-down position can only accommodate an aircraft up to the size air- craft it was designed for, while a Parking position is the space or area taken by any size aircraft within the parking area. • For this Guidebook, the apron PARKING AREA is only the portion of the apron acceptable for aircraft to park and does not include the taxilane or TOFA. AC-13A indicates that tie-down anchors should be placed at the wingtips and the tail. How- ever, based on the tie-down points on a Beech Baron 58 and similar sized aircraft, the wingtip tie-down anchors are approximately 10 feet away from the tie-down points. This position would require very long ropes and may restrict which aircraft can tie-down due to the different tie- down points on different aircraft. Placing the tie-down anchors for the wings at the ends of the painted “T”s, which are 19 feet apart, will provide greater flexibility for a variety of aircraft and will not require such long ropes. While a location for the anchors is recommended, each airport should consider its situation when locating the anchors. This layout is similar in size to the majority of tie-downs found at the sample airports. Figure B-1 depicts the tie-down dimensions. Basing a tie-down position on a larger aircraft will cause the area required to tie-down a similar number of aircraft to grow dramatically with only marginal benefits. For example, the area needed

126 Guidebook on General Aviation Facility Planning Source: Delta Airport Consultants, Inc. Figure B-1. Tie-down dimensions for Beech Baron 58 aircraft per AC 150/5300-13A. Source: Delta Airport Consultants, Inc. Figure B-2. Parking area for 10 Beech Baron 58 tie-down positions. to tie-down 10 nested Piper PA-31 Navajos would require 24% more pavement than an area required for 10 Baron 58s. The area for 10 Baron 58s can be configured to accommodate up to four larger aircraft which could safely accommodate a Piper PA-31 Navajo along with larger and smaller aircraft. Using the AC, a tie-down layout for 10 Baron 58s was developed and is depicted in Figure B-2. Figure B-3 uses the same parking area but is marked for four larger aircraft. The tie-down anchors can still be installed for the 10 tie-down positions if there is a need.

Tie-Down Parking Areas 127 As shown in Figures B-3 and B-4, the same parking area can accommodate either 10 small Group I aircraft in a nested configuration or four large Group I or small Group II aircraft in standard configuration. The area can also be marked to accommodate both sized aircraft to meet the needs of the airport. The tie-down layout is only a recommendation for planning purposes. Space constraints or a different size aircraft may require a different configuration. Depth of the Parking Area While Group II aircraft have wingspans less than 79 feet, they have lengths that vary between 50 feet and 90 feet. To right size the apron, the depth of the parking position must be determined. Using the minimum depth of a Group I nested parking area of 66 feet as determined previously, all current Group I aircraft in use can be accommodated without impacting the adjacent TLOFAs. The current longest Group I aircraft in use is the Learjet 60, which at 58 feet will fit within this depth. If your apron is a Group I apron, then you are finished determining the depth. Note: The lighter lines depict the nested tie-down positions available for small aircraft Source: Delta Airport Consultants, Inc. Figure B-3. Parking area for 10 Beech Baron 58 tie-down positions marked for larger aircraft. Note: The lighter lines depict other available parking positions Source: Delta Airport Consultants, Inc. Figure B-4. Tie-down positions marked for both small and large aircraft.

128 Guidebook on General Aviation Facility Planning If your apron needs to accommodate Group II aircraft, you now need to determine what length of aircraft you will need to accommodate. The 66 foot depth of the nested tie-down park- ing area can accommodate approximately 54% of the existing Group II aircraft in use. Sampling of Group II aircraft less than 66 feet long: • Cessna Citation CJ2 • Cessna Citation XLS • Dassault Falcon 50 • Gulfstream G150 • Hawker 800 • Beech King Air C90 • Embraer Phenom 300 If you anticipate Group II aircraft longer than 66 feet, a depth of 75 feet would accommodate approximately 83% of the existing Group II aircraft in use. Sampling of Group II aircraft between 66 and 75 feet long: • Gulfstream G280 • Cessna Citation X • Bombardier Challenger 300 • Bombardier Challenger 605 • Hawker 4000 • Dassault Falcon 900 If you anticipate Group II aircraft longer than 75 feet, a depth of 100 feet would accommodate 100% of the existing Group II aircraft in use. Sampling of Group II aircraft between 75 feet long and 100 feet long: • Gulfstream G350 • Gulfstream G450 • Embraer Legacy 600 While the proposed apron depths are more than the longest aircraft in each range, the extra distance provides flexibility and a margin of error if the aircraft is not centered in the parking area. In all cases, the Group I tie-down positions are centered within the parking area. These depths are only a recommendation for planning purposes. Space constraints or a dif- ferent size aircraft may require a different depth. Add Taxiway and Taxilane Areas to Access the Parking Area Now that the parking areas have been established, the appropriate TLOFA and taxiway object free areas (TOFA) have to be added to the apron. Chapter 4 of AC-13A will provide the dimensions for the clear areas. It is very important to provide Group II taxilanes for Group II parking positions. Figures B-5 and B-6 are examples of complete apron layouts with tie-downs, parking areas, taxilanes, and taxiways. For airports not staffed full time or that do not have a full-time parking attendant with the ability to position aircraft to fit in the available space, parking positions should be provided to allow power-in, power-out operations of the largest aircraft anticipated. Group III Aprons The aprons discussed above are for Group I and Group II aircraft. If Group III aircraft are anticipated, similar to a Gulfstream G550 or Bombardier Global Express, the frequency and number of these sized aircraft must be considered prior to deciding on the size of your apron.

Tie-Down Parking Areas 129 Source: Delta Airport Consultants, Inc. Figure B-5. Sample Group II Apron Layout One. Source: Delta Airport Consultants, Inc. Figure B-6. Sample Group II Apron Layout Two.