Appendix F
General Aviation Flight Scenarios—1994 and 2015

This appendix contains descriptive scenarios of two sample general aviation flights. The first scenario describes and critiques the current aviation weather system; the second scenario describes the system that may exist in the year 2015. Both scenarios are quoted verbatim from Appendix 6 of Federal Aviation Administration (FAA) Order 7032.15 (FAA, 1994). These scenarios are similar to those offered independently by the National Research Council in Weather for Those Who Fly (NRC, 1994).

The following acronyms appear in this appendix:


AFSS

Automated Flight Service Station

ARTCC

Air Route Traffic Control Center

ATC

Air Traffic Control

ATCS

Air Traffic Control Specialist

ATIS

Automatic Terminal Information Service


CD

Clearance Delivery


DUATS

Direct User Access Terminal Service


EDCT

Expected Departure Clearance Time

EFAS

En Route Flight Advisory Service


FAA

Federal Aviation Administration


NOTAM

Notice to Airmen


PIREP

Pilot Weather Report


RVR

Runway Visual Range


SIGMET

Significant Meteorological Information Report


Z

Zulu time



Scenario One: 1994

Date:

December 1, 1994

Departure Airport:

Washington National, Washington, D.C.

Arrival Airport:

Pittsburgh International, Pittsburgh, Pennsylvania

Aircraft:

N1234A, BE30/A

Proposed Departure Time:

1045 Zulu (Z)

While planning a flight from the Washington National Airport to the Pittsburgh International Airport, the pilot of N1234A telephones the Leesburg Automated Flight Service Station (AFSS) to request a standard weather briefing from the air traffic control specialist (ATCS).1

The ATCS identifies and reads, verbatim, three flight precaution advisories, one for instrument flight rules conditions, one for icing, and a Convective Significant Meteorological Information report (SIGMET) of thunderstorm activity that is near the aircraft's intended route of flight. Radar reports from four radar sites provide the intensity, movement, and cloud tops of the thunderstorm activity described in the Convective SIGMET. These radar reports are 45 minutes old and will not be updated for at least another 15 minutes. The data contained in these written reports does not match the depiction of thunderstorms displayed on the ATCS's weather radar presentation.

Notice to Airmen (NOTAM) information provided for the route of flight is two pages long and includes all special purpose NOTAMs for the United States. The pilot interrupts the ATCS twice to locate or confirm unfamiliar locations.

The ATCS issues the forecast freezing level and winds aloft, including temperature data, based in part on data observed from the previous day. Pilot Weather Reports (PIREPs) are not available describing tops of the cloud layer where icing is forecasted. The ATCS notes that terminal forecasts will be reissued shortly. The area forecast and flight precaution advisories have been updated; however, this data does not coincide with the current Washington National terminal forecast.

After completing the preflight briefing, the pilot of N1234A files a flight plan. The AFSS ATCS enters the flight plan into a computer that transmits the flight plan to the Host computer at the Washington Air Route Traffic Control Center (ARTCC). An air traffic control (ATC) clearance, in the form of a paper strip, will be posted at the Washington National clearance delivery position in the tower cab.

The pilot of N1234A obtains an alphanumeric weather update from one of two FAA-funded Direct User Access Terminal Service (DUATS) vendors. The pilot sifts

1  

This appendix uses "ATCS" to refer to both air traffic controllers and flight service specialists.



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--> Appendix F General Aviation Flight Scenarios—1994 and 2015 This appendix contains descriptive scenarios of two sample general aviation flights. The first scenario describes and critiques the current aviation weather system; the second scenario describes the system that may exist in the year 2015. Both scenarios are quoted verbatim from Appendix 6 of Federal Aviation Administration (FAA) Order 7032.15 (FAA, 1994). These scenarios are similar to those offered independently by the National Research Council in Weather for Those Who Fly (NRC, 1994). The following acronyms appear in this appendix: AFSS Automated Flight Service Station ARTCC Air Route Traffic Control Center ATC Air Traffic Control ATCS Air Traffic Control Specialist ATIS Automatic Terminal Information Service CD Clearance Delivery DUATS Direct User Access Terminal Service EDCT Expected Departure Clearance Time EFAS En Route Flight Advisory Service FAA Federal Aviation Administration NOTAM Notice to Airmen PIREP Pilot Weather Report RVR Runway Visual Range SIGMET Significant Meteorological Information Report Z Zulu time Scenario One: 1994 Date: December 1, 1994 Departure Airport: Washington National, Washington, D.C. Arrival Airport: Pittsburgh International, Pittsburgh, Pennsylvania Aircraft: N1234A, BE30/A Proposed Departure Time: 1045 Zulu (Z) While planning a flight from the Washington National Airport to the Pittsburgh International Airport, the pilot of N1234A telephones the Leesburg Automated Flight Service Station (AFSS) to request a standard weather briefing from the air traffic control specialist (ATCS).1 The ATCS identifies and reads, verbatim, three flight precaution advisories, one for instrument flight rules conditions, one for icing, and a Convective Significant Meteorological Information report (SIGMET) of thunderstorm activity that is near the aircraft's intended route of flight. Radar reports from four radar sites provide the intensity, movement, and cloud tops of the thunderstorm activity described in the Convective SIGMET. These radar reports are 45 minutes old and will not be updated for at least another 15 minutes. The data contained in these written reports does not match the depiction of thunderstorms displayed on the ATCS's weather radar presentation. Notice to Airmen (NOTAM) information provided for the route of flight is two pages long and includes all special purpose NOTAMs for the United States. The pilot interrupts the ATCS twice to locate or confirm unfamiliar locations. The ATCS issues the forecast freezing level and winds aloft, including temperature data, based in part on data observed from the previous day. Pilot Weather Reports (PIREPs) are not available describing tops of the cloud layer where icing is forecasted. The ATCS notes that terminal forecasts will be reissued shortly. The area forecast and flight precaution advisories have been updated; however, this data does not coincide with the current Washington National terminal forecast. After completing the preflight briefing, the pilot of N1234A files a flight plan. The AFSS ATCS enters the flight plan into a computer that transmits the flight plan to the Host computer at the Washington Air Route Traffic Control Center (ARTCC). An air traffic control (ATC) clearance, in the form of a paper strip, will be posted at the Washington National clearance delivery position in the tower cab. The pilot of N1234A obtains an alphanumeric weather update from one of two FAA-funded Direct User Access Terminal Service (DUATS) vendors. The pilot sifts 1   This appendix uses "ATCS" to refer to both air traffic controllers and flight service specialists.

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--> through numerous pages of data to determine which information is pertinent to the flight, translating, interpreting, and resolving disparities in coded text data to form a mental image of expected flight conditions. The pilot, now seated in the aircraft, radios Washington National clearance delivery (CD) approximately 15 minutes prior to the proposed departure time to obtain an ATC clearance to Pittsburgh International Airport. The ATCS at CD relays the ATC clearance to N1234A. However, due to restricted ceiling and visibility and wet runway conditions at the destination airport, N1234A encounters a 1-hour ground delay at the Washington National Airport. CD issues an Expected Departure Clearance Time (EDCT) of 1145Z, the time N1234A can expect to depart. This is an unanticipated delay. The pilot remains in the aircraft, monitoring CD position for any possible update of the EDCT. The CD manually passes the ATC clearance, including the EDCT, to the Washington National ground controller. At the appropriate time, the ground controller issues taxi instructions to N1234A. Due to reduced visibility and fog, the ground controller is not able to observe N1234A taxi. This requires the ground controller to maintain a mental picture of the aircraft's location. The ground controller solicits and receives position reports from N1234A. This verbiage continues until the aircraft reaches the active runway. N1234A is then instructed to contact Washington National local controller. The local controller issues the current wind, runway visual range (RVR), departure instructions, and a take-off clearance to N1234A. Once airborne, N1234A is instructed to contact Washington National departure control. The aircraft is now under radar control. While N1234A is climbing out from the airport, the pilot hears the departure controller broadcast a SIGMET report concerning a layer of icing south of Washington National Airport. The area described does not impact the flight of N1234A. The departure controller solicits from N1234A a report of the cloud bases and tops. This information is provided, but due to ATCS workload it is not given distribution outside of the radar facility. N1234A is instructed to contact the Washington ARTCC. As the aircraft flies through the ARTCC airspace, the pilot asks an ARTCC ATCS for the weather conditions. The controller advises the pilot to contact Flight Watch, the En Route Flight Advisory Service (EFAS), for Convective SIGMETs and weather radar information. The Flight Watch ATCS manually plots the position of the aircraft, based on navigational aid information, to determine the aircraft's position in reference to the thunderstorms depicted on the radar display. The Flight Watch ATCS has the capability of relaying live weather data to the pilot, however, supplemental information such as thunderstorm intensity and movement is now 1 hour old and may not be applicable. The Flight Watch ATCS issues PIREPs from other aircraft in the same vicinity indicating all aircraft are reporting no icing at N1234A's altitude. N1234A provides a PIREP to the Flight Watch ATCS on tops of clouds along the route. The ATCS, now being contacted by two other aircraft, cannot enter the PIREP into the computer until all other contacts have been completed. Additionally, the pilot has been off the ARTCC frequency while the weather question is being answered. Some time later, another ARTCC ATCS solicits from N1234A a top of clouds report and inquires as to any additional cloud layers above. The ATCS passes this information on as a PIREP. N1234A is able to climb to an altitude that is above the clouds and precipitation. The freezing level is no factor during this portion of the flight. The ARTCC ATCS broadcasts a center weather advisory. This advisory has no impact on N1234A's flight. N1234A has the same concerns entering the Pittsburgh terminal airspace as experienced on climb-out from Washington National. The pilot is concerned with cloud tops, thunderstorms, freezing levels, turbulence, etc. N1234A is also concerned with airfield conditions and equipment status. N1234A listens to the Automatic Terminal Information Service (ATIS) before being instructed to contact the Pittsburgh approach controller. The ATIS does not provide all the information N1234A would like to have. Though this information is current at the time of broadcast, conditions are changing very rapidly, requiring most of this same information to be reissued, verbally, by the terminal ATCS. N1234A hears the terminal ATCS broadcast a SIGMET. This information describes an area affected by a line of thunderstorms. The pilot, not familiar with the description of the affected area, checks a map to locate the area described. The area is 40 miles northwest of Pittsburgh and does not affect the flight. There are thunderstorms around much of the Pittsburgh International Airport. These thunderstorm echoes, depicted on the ATCS's display, are derived from a ground-based ASR-9 [air traffic control radar] sensor. The pilot's airborne weather radar depicts the contours of the thunderstorms differently in area and intensity, and does not show thunderstorm activity behind the first significant return. The terminal ATCS plans to vector the aircraft to the north side of the thunderstorms. The pilot's display indicates clear passage to the south side. The pilot and ATCS are receiving weather information from different sources. Each is trying to describe the presentation they see to the other.

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--> The terminal ATCS solicits a PIREP from N1234A. Due to a sustained increase in workload, it is not passed on to the appropriate AFSS for 20 minutes. N1234A is issued the runway braking action and RVR by the terminal ATCS, then receives an approach clearance with instructions to contact the Pittsburgh tower local controller. The local controller reissues to N1234A wind information, runway braking action, and the RVR. N1234A receives a clearance to land. In retrospect, N1234A received weather information that was often incomplete, inconsistent, and outdated. The AFSS ATCS spent valuable time interpreting alphanumeric data. Radar information was often too old to be useful by itself. The Flight Watch ATCS was unable to relay accurate information on thunderstorm cells and the exact location of potential icing and turbulence. The PIREPs were not disseminated at their time of receipt due to equipment limitations. The terminal and ARTCC ATCSs were overly involved with the issuance of routine weather information. The exchange of weather information between pilot and ATCS was time-consuming, work-intensive, and caused frequency congestion that affected airspace capacity and ATC efficiency. Scenario Two: 2015 Date: December 1, 2015 Departure Airport: Washington National, Washington, D.C. Arrival Airport: Pittsburgh International, Pittsburgh, Pennsylvania Aircraft: N1234A, BE30/S Proposed Departure Time: 1045 Z While planning a flight from the Washington National Airport to the Pittsburgh International Airport, the pilot of N1234A obtains a detailed weather briefing from the ATCS at the preflight position at the Leesburg AFSS. The AFSS has composite display available for the pilot's entire route of flight which allows the specialist to describe individually flight tailored information that indicates precisely where a line of thunderstorm activity will be located. The display is capable of overlaying individual areas with annotations of tops, intensity, and movement. The need for Convective SIGMET and radar reports has been eliminated by current and forecast annotated radar information. NOTAM information for the route of flight is displayed only for navigational aids and landing areas pertinent to the route of flight. Turbulence, icing, and winds aloft information is denoted into a weather severity index by route and altitude and displayed graphically, eliminating the need for vague and extensive weather advisories. Radar reflectivity information is confirmed by satellite data which can be looped and overlaid over other graphics. PIREPs have been automatically received via data link from aircraft in flight and are included in the graphic display. The ATCS is no longer required to read, verbatim, routine alphanumeric data. The ATCS queries the computer for the most favorable flight altitude for the BE30. The most favorable altitude and associated wind data are displayed graphically for the route. The location of wind direction and speed changes is clearly depicted. The pilot of N1234A could have obtained the same graphics and weather presentation by accessing the DUATS located at a fixed base operator or through a home personal computer. The data base and graphics utilized by DUATS are the same data base utilized by the Leesburg AFSS. The pilot of N1234A files a flight plan via a computer terminal. It is transmitted to the Host computer at the Washington ARTCC. An ATC clearance is electronically posted at the Washington National clearance delivery position in the tower cab. Simultaneously, the pilot of N1234A receives an ATC clearance to the Pittsburgh International Airport through the predeparture clearance delivery function at the Washington National airport traffic control tower. N1234A receives an EDCT of 1145Z, a 1-hour ground delay at the Washington National Airport due to restricted ceiling and visibility and wet runway conditions at the destination airport, Pittsburgh International. The pilot is able to plan for this delay in departure. Having no need to reconfirm any clearance information, N1234A calls Washington National ground control for taxi instructions. Ground control has prior notification that N1234A will call due to a scroll of an EDCT list. The controller is aware that the pilot has been delayed on the ground and that the ATC system is now able to allocate airspace for this aircraft. Automation tools help direct the aircraft to the appropriate runway as reduced visibility and fog restrict the ATCS's ability to see the aircraft taxi. Ground control monitors N1234A's progress on the airport surface detection equipment. Some limited verbal communications are still required. The Washington National local controller issues departure instructions and a takeoff clearance to N1234A. The aircraft is data link equipped; this is annotated electronically on the ATCS's display. The requirement to issue wind and RVR information is no longer necessary, as this information is transmitted via data link. Data link technology enables the local controller to devote more time and attention to the separation and sequencing of aircraft. Once airborne, N1234A is instructed to contact Washington National departure control. The aircraft is now under radar control.

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--> While N1234A is climbing out from the airport, pertinent weather affecting the route of flight is transmitted via data link to the aircraft, with no ATC involvement. N1234A files a PIREP on the bases and tops of cloud layers via data link. This PIREP is automatically disseminated to users in need of such information, including ATC. Throughout the flight, N1234A receives and solicits weather information through a common data base via an onboard computer. Wishing to confirm the exact location of predicted thunderstorm activity, N1234A contacts Flight Watch. The Flight Watch ATCS enters the aircraft's identification into the computer. The aircraft's position is automatically depicted on the display along with the projected route of flight. The Flight Watch ATCS is able to provide N1234A with individually flight tailored information that depicts the exact location of hazardous weather and projections of movement in time and distance along the route of flight. The Washington ARTCC receives information indicating a severe thunderstorm in the flight path of N1234A. The ARTCC ATCSs are able to depict this, in three dimensions, on their common console. Planning commences to direct N1234A, and all other affected aircraft, from this thunderstorm. Before N1234A reaches this thunderstorm, a reroute is received from ATC via data link ensuring clearance from it. N1234A, able to depict the same presentation of the thunderstorm on its onboard computer, has anticipated the reroute. PIREP and NOTAM information are similarly transmitted via data link to the aircraft. N1234A listens to the ATIS before being instructed to contact the Pittsburgh approach controller. The ATIS broadcast, along with the accurate weather information received throughout the flight, prepares the pilot for arrival to Pittsburgh. Both the pilot of N1234A and the approach controller share the same weather information, in graphic presentation. N1234A is vectored around hazardous thunderstorms north of the airport. The pilot anticipated the situation and was able to plan for this reroute. N1234A, during the arrival phase of flight, receives continuous wind, braking action, and RVR information from the heads-up display that interfaces with the data base. The terminal ATCS issues an approach clearance to N1234A with instructions to contact the Pittsburgh tower local control. The local controller, at this point, issues a clearance to land N1234A. The local controller also receives continuous wind, braking action, and RVR information, for ATC planning purposes, from the beads-up display in the tower cab. In retrospect, N1234A and the ATC system received weather information which was complete, consistent, pertinent, and accurate. The pilot was able to obtain an individually tailored preflight briefing from the AFSS ATCS in a minimum amount of time. The ATCS was able to focus on providing a service versus spending a large amount of time analyzing and interpreting data. The terminal and en route ATCSs utilized weather information for strategic and tactical ATC planning. The terminal and ARTCC ATCSs, no longer a conduit of routine information, were able to provide much better ATC services to N1234A. References FAA (Federal Aviation Administration). 1994. FAA Order 7032.15: Air Traffic Weather Needs and Requirements. Washington, D.C.: FAA. NRC (National Research Council). 1994. Weather for Those Who Fly. National Weather Service Modernization Committee, National Research Council. Washington, D.C.: National Academy Press.