Advisory Circular
Subject: AIRSPACE FLOW PROGRAM Date: 5/1/06 Initiated by: AJR-1 AC No:
90-102
1. PURPOSE.
This Advisory Circular provides guidance to customers of the National Airspace System (NAS) regarding a new traffic management process for managing flights through a constrained area.
In this process, traffic managers identify a constraint in the en route system, develop a real-time list of flights that are filed into the constrained area, and implement an Airspace Flow Program (AFP). Pilots need to be aware that an AFP distributes expect departure clearance times (EDCT) in order to meter air traffic demand through the area.
Examples of constraints include thunderstorm activity, turbulence, and periods of excess demand. The list of flights includes aircraft that have filed flight plans, filed early intent flight plans, or operate in the constrained area based on historical flight plan data.
2. WHY WAS THE AFP DEVELOPED?
A ground delay program (GDP) is used by traffic managers to meter the flow of arrival traffic at an airport where demand exceeds capacity because of weather or congestion.
Multiple, concurrent GDPs have been used during the summer months to manage the impact of en route severe weather. This approach was inefficient because it often delayed flights that did not directly contribute to the problem and assigned no delay to other flights that traversed the constrained airspace. Additionally, this method meant that a small subset of airports, usually those with the greatest demand, incurred a disproportionate amount of delay.
Airline and General Aviation representatives indicated a need for the Federal Aviation Administration (FAA) to implement an equitable method to manage en route constraints.
An AFP is designed to distribute delays among all relevant flights that traverse a constrained region of airspace.
3. WHAT BENEFITS ARE PROVIDED BY AN AFP?
An AFP provides:
• more precise control of airspace demand by avoiding the imposition of unnecessary delay on flights that do not use the constrained airspace.
AC No: 90-102 5/1/06 2
• an equitable distribution of delays among flights filed through the constrained airspace.
• customers with more predictability, flexibility, and options during a severe weather event.
4. HOW DOES AN AFP AFFECT MY FLIGHT?
When the air traffic demand in a constrained area is projected to exceed capacity, traffic managers at the Air Traffic Control System Command Center (ATCSCC) will follow a predefined coordination process and may issue an AFP for the constrained airspace.
If an AFP is issued and a flight is included, the pilot will receive an EDCT.
5. WHAT IS AN EDCT?
An EDCT is a departure time generated by the traffic manager’s Flight Schedule Monitor software program that specifies when a flight should depart. Meeting the departure time is important because it allows traffic managers to properly meter flights through a constrained area.
FIGURE 1. AIR TRAFFIC DEMAND SHOWN ON A FLIGHT SCHEDULE MONITOR
6. HOW DO I FIND OUT IF MY FLIGHT IS INCLUDED IN AN AFP?
When an AFP is issued, the FAA will send an Advisory that is accessible at http://www.fly.faa.gov/adv/advAdvisoryForm.jsp
An AFP will also appear in graphic and text formats on the ATCSCC Operational Information System page at http://www.fly.faa.gov/ois/
Your flight is included if it falls within the parameters of the Advisory – between the specified altitudes, crossing an AFP, and destined to the specified areas. For example, your flight is filed between 12,000 feet MSL and FL600, crosses an AFP located in western Pennsylvania, and lands at an airport within New York Center or Boston Center.
7. HOW DO I FIND OUT IF MY FLIGHT HAS AN EDCT?
At airports with an airport traffic control tower, controllers will provide you with the EDCT.
If you are departing an airport without a control tower, you should determine if your flight has an EDCT prior to departure. To do so, you may contact:
• the overlying TRACON or En Route Center by radio, or telephone, if available. The controller has a process for determining if your flight has an EDCT.
• Flight Service. The controller has a process for determining if your flight has an EDCT.
• your company. Some corporate flight departments have a process for contacting the ATCSCC to determine if your flight has an EDCT.
You may also visit the ATCSCC’s website at http://www.fly.faa.gov/edct to determine if your flight has an EDCT or to determine if your EDCT has changed.
This website will provide information regarding the location and reason for an AFP. It will also provide a “Look Up” function to determine if your flight has received an EDCT.
FIGURE 2. EXAMPLE OF THE EDCT LOOK UP WEB PAGE
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8. WHAT IF I DEPART VFR, PICK UP MY IFR CLEARANCE WHEN AIRBORNE, AND THEN DISCOVER I HAVE AN EDCT?
First, it is important for you to check – before you depart – to determine if your flight is included in an AFP.
Depending on the severity of the constraint, you can anticipate the following options to be exercised by traffic managers. You may:
• be assigned airborne holding to provide the delay necessary for your flight to arrive at the AFP controlled time of arrival (CTA); or
• be rerouted to avoid the AFP altogether; or
• be offered an intermediate landing. The flight should land at the intermediate airport to provide the delay necessary for your flight to arrive at the AFP CTA; or
• be permitted to enter the AFP with minimal delay.
9. WHAT IF I MISS THE ASSIGNED EDCT OR NEED TO ARRANGE A DIFFERENT TIME?
You have a window of time in which to depart and not miss the EDCT.
Flights are asked to depart as close to the control time as possible. If conditions warrant, you may depart 5 minutes before the EDCT and up to 5 minutes after.
Outside of that window, you may exercise the following options:
• At airports with a control tower, the controller has a process for requesting a new time and can assist you.
• At airports without a control tower, you may contact:
o the overlying TRACON or En Route Center. The controller has a process for requesting a new time.
o Flight Service. The controller has a process for requesting a new time.
o your company. Most airlines and some corporate flight departments have a process for contacting the ATCSCC to request a new time.
10. WHAT OPTIONS DO I HAVE BESIDES TAKING A GROUND DELAY?
• Route out of an AFP.
If there is another acceptable route available that would take the flight out of an AFP, you may choose to refile the flight plan. The software will recognize that the flight is no longer in an AFP.
• Make a stop en route.
You may elect to land at an intermediate airport to provide the delay necessary for the flight to arrive at an AFP controlled time of arrival.
11. WHAT HAPPENS IF I FILE A NEW FLIGHT PLAN INTO AN EXISTING AFP?
If you file a new flight plan into an existing AFP, the flight will be treated as a popup.
Your flight will be assigned an EDCT consistent with the delay received by other flights filed to enter the AFP at about the same time.
12. WHAT HAPPENS IF I ROUTE OUT OF ONE AFP AND INTO ANOTHER AFP?
If you file a flight plan out of an AFP and into another, the flight will be treated as a popup. Your flight will be assigned an EDCT consistent with the delay received by other flights filed to enter an AFP at about the same time.
13. WHAT HAPPENS WHEN MY FLIGHT ALREADY HAS AN EDCT FOR AN AIRPORT GROUND DELAY PROGRAM?
If your flight is included in both an airport GDP and an AFP, the EDCT for the GDP will take precedence and you will not be issued another EDCT.
14. WHAT HAPPENS WHEN WEATHER CONDITIONS CHANGE AND THE CAPACITY IN AN AFP CHANGES?
It is recognized that the predicted demand through an AFP -- and the weather impacting the area -- will change substantially over time. Demand through the constrained airspace may exceed or fall below capacity or weather conditions in the airspace may worsen or improve. When the conditions warrant, traffic managers will take steps to coordinate and implement revisions to an AFP. In a revision, AFP entry slots are recomputed so that demand is again metered to meet capacity and new EDCTs are sent to the en route centers, the control towers, and the customer flight operation centers.
If the weather that necessitated an AFP dissipates or if the demand falls well below capacity the AFP will be cancelled.
Michael J. Sammartino Director of System Operations