Section 10. Ground Delay Programs


Ground Delay Programs (GDP) must be applied to all aircraft departing airports in the contiguous U.S., as well as, from select Canadian airports. Aircraft that have been assigned an EDCT in a GDP should not be subject to additional delay. Exceptions to this policy are miles-in-trail and departure/en route spacing initiatives that have been approved by the ATCSCC. GDP procedures do not apply to facilities in Alaska.


A GDP is a TM process administered by the ATCSCC; when aircraft are held on the ground in order to manage capacity and demand at a specific location, by assigning arrival slots. The purpose of the program is to support the TM mission and limit airborne holding. It is a flexible program and may be implemented in various forms depending upon the needs of the air traffic system. The EDCT is calculated based on the estimated time en route and the arrival slot. It is important for aircraft to depart as close as possible to the EDCT to ensure accurate delivery of aircraft to the impacted location. GDPs provide for equitable assignment of delays to all system users.


In the past, GDPs were issued manually, followed by software called Groverjack. These systems were based on the Official Airline Guide data, and did not take into account dynamic changes the system users made to their schedule. The Flight Schedule Monitor (FSM) was developed through the collaborative decision making (CDM) process with system users to provide a dynamic method of implementing and managing GDPs. System users submit schedule changes to FSM, which keeps a current up-to-the-minute schedule of flights. The Flight Schedule Analyzer (FSA) is used to monitor and review the effectiveness of GDPs.

  1. GDP Parameters. Aircraft departing within a defined geographical area are initially assigned delay in the GDP. This area is developed using the FSM, and may consist of one or more ARTCCs and one or more Canadian airports. All departure aircraft will receive an EDCT to the GDP airport.
  2. Delay Assignment (DAS). A method for assigning delays to aircraft based on the GDP parameters. The delay assignment is calculated in 15-minute increments and appears as a table in TFMS.
  3. General Aviation Airport Program (GAAP). A method for assigning delays to aircraft based on arrival slot availability at the airport.
  4. Unified Ground Delay Program (UDP). A preferred method that addresses the mix of scheduled and unscheduled (i.e., pop-ups) demand based on the following parameters: number of reserved pop-ups, target delay multiplier, and delay limit.

GDPs may be modified and affected due to changing conditions. Some of those variables include, but are not limited to, GDP Adjustments, Diversion Recovery, and User Options.

  1. GDP Adjustments. The ATCSCC may make revisions and compressions to the GDP as conditions at the airport or within the airspace change.
  2. Diversion Recovery. During periods where there are a large number of diverted flights, the GDP may be adjusted to provide priority for the recovery of aircraft diversions over non‐diverted flights.
  3. User Options. Users are permitted to exchange and substitute Controlled Times of Arrival (CTA) congruent with CDM agreements concerning substitutions.

Upon receipt of information that traffic flows have been or are expected to be impacted and that significant delays will result, the ATCSCC must:

  1. Conference affected facilities and system users, as appropriate, to determine AARs and review system demand and other known or anticipated factors.
  2. Determine when implementation of a GDP is appropriate and the flow rate to be used. Consideration will be given to the impact on other air traffic control facilities and user groups.
  3. Transmit an ATCSCC advisory providing information to air traffic control facilities and user groups about the implementation, revision, compression, and cancellation of a GDP. Except for the cancellation of a GDP, the ATCSCC advisory must include the following items:
  1. Airport.
  2. Delay Assignment Mode.
  3. Aggregate Demand List (ADL) Time.
  4. Program Type. (Optional)
  5. Arrivals Estimated For.
  6. Program Rate.
  7. Flights Included.
  8. Scope.
  9. Additional Facilities Included.
  10. Exempt Facilities.
  11. Canadian Airports Included. (When applicable.)
  12. Delay Assignment Table Applies To. (Optional.)
  13. Maximum Delay or Delay Limit. (As appropriate).
  14. Average Delay. (Optional).
  15. Reason.
  16. Remarks.
  1. Transmit the DAS table to ARTCC TMUs via TFMS and the NADIN circuits, if appropriate.
  2. Transmit EDCTs to ARTCCs and linked system users.


A CT message is automatically transferred to the ARTCC's computers by the ETMS and appears on flight progress strips as an EDCT. In the event of a communication failure between the ETMS and the NAS computer, the CT message can be manually entered by the ARTCC TMC with ATCSCC approval.

  1. Input ATCSCC coordinated modifications to EDCT into FSM.


Modifications may be made through TFMS.

  1. Continually monitor, adjust, and cancel GDPs, as appropriate, and transmit an ATCSCC advisory as necessary.
  2. Provide an EDCT or DAS when requested by an ARTCC.
  3. Coordinate with affected facilities to ensure the GDP is adequately managing the demand.
  4. Obtain arrival and departure counts from affected facilities, as appropriate.
  5. Utilize the TSD and FSM to monitor traffic flow patterns, obtain estimated arrival counts, or obtain airborne delay estimates.
  6. When appropriate and workload permitting, utilize FSA to monitor the GDP.

The ARTCC TMU must:

  1. Issue a General Information message (GI) to all towers and FSSs advising of the GDP. In some instances, verbal notification, in addition to a GI, may enhance the dissemination of information.
  2. Issue EDCT information to non-FDEP/FDIO equipped towers and other users in sufficient time for proper planning and control actions. This does not include non-FDEP towers that are satellites of TRACON/RAPCON facilities. The TRACON/RAPCON is responsible for satellite EDCTs.
  3. Evaluate the Delay Assignment Mode and assign EDCTs, as appropriate.
  1. For DAS, assign an EDCT using the DAS table to aircraft that do not receive an EDCT and are destined to an affected airport within their ARTCC boundaries. Contact the ATCSCC for aircraft destined to an airport outside their ARTCC boundaries.
  2. For GAAP, contact the ATCSCC for an EDCT for aircraft that do not receive an EDCT.
  1. Keep the ATCSCC apprised of cancellations and diversions to or from the affected airport.
  2. Relay information to the ATCSCC when advised by a terminal facility about EDCT issues.
  3. Request a revised EDCT from the ATCSCC when notified by the terminal facility that a flight will be unable to depart within EDCT parameters as defined in FAA Order JO 7110.65, Air Traffic Control.
  4. Advise the appropriate terminal facility or controller after receiving a revised EDCT from the ATCSCC.
  5. Utilize FSM to obtain information about the GDP, and may utilize FSA to monitor the GDP.

The Terminal TMU must:

  1. Utilize FSM, if available, to obtain EDCT information.
  2. Obtain from the ARTCC TMU and apply the appropriate delay to:
  1. Airfile aircraft destined to the affected airport.
  2. Any other flight not assigned an EDCT.
  1. Ensure that internal flight plans are entered into the EAS computer in order to receive an equitable delay.
  2. Ensure the EDCT is included in the flight clearance when a GDP is in effect. If an EDCT is not received and a GDP is in effect, contact the ARTCC TMU for an EDCT.
  3. Issue EDCT information to non-FDEP/FDIO equipped towers and other users in sufficient time for proper planning and control actions.
  4. To the extent possible, plan ground movement of aircraft destined to the affected airport so that flights will meet the parameters in FAA Order JO 7110.65, Air Traffic Control. If unable, advise the ATCSCC, through the appropriate protocol.
  5. Ensure aircraft with an EDCT that are in a Ground Stop are not released without the approval of the issuing authority for the Ground Stop.
  6. When a GDP is in effect for the local airport, forward the total number of hourly arrivals and departures to the ATCSCC, through the appropriate protocol, as soon as possible after each hour in order that timely GDP adjustments may be made.
  7. Coordinate closely with the appropriate ARTCC TMU on conditions affecting current or projected arrival rates.


Terminal facilities may utilize FSM to obtain information concerning the GDP, including EDCTs, and may utilize FSA to monitor the GDP.

  1. All requests to amend EDCTs earlier than the current EDCT must be coordinated with the ATCSCC.
  2. Facilities without FSM should contact their overlying facility to request a new EDCT.
  3. Modifications to EDCTs for a time later than the current EDCT must be processed in accordance with the following guidelines:
  1. The pilot/operator must be in contact with ATC.
  2. Facilities with FSM may utilize the EDCT Change Request (ECR) tool to assign a new EDCT utilizing the Slot Credit Substitution (SCS) method, followed by the unlimited delay option, when available.
  3. If the time generated by ECR is not acceptable (normally two hours of additional delay or longer), the facility must contact the ATCSCC through the appropriate protocol, for a new EDCT.
  1. All EDCTs amendments not obtained using the ECR tool must be coordinated via the appropriate protocol.
  1. When conditions no longer warrant ground delays, the ATCSCC must:
  1. Conference all affected facilities and system users, as appropriate, to develop an operational plan for release of ground delayed traffic into the system.
  2. Transmit an ATCSCC advisory stating the GDP has been cancelled. The advisory must include the following items:
  1. Airport.
  2. ADL Time.
  3. Reason.
  4. Remarks.
  1. Purge flights from the TFMS.
  1. The ARTCC TMU and the Terminal TMU must:
  1. Issue cancellation information to underlying facilities, using normal communication methods, in sufficient time for proper planning and control actions.
  2. Notify facility personnel, as appropriate, of the cancellation.
  1. The ATCSCC must document all pertinent information related to the GDP in their position logs, including, but not limited to, the start and stop times and the reason for the GDP.
  2. The ARTCC TMU and the Terminal TMU must document all pertinent information related to the GDP.

When a GDP is in effect, system users may exercise options other than ground delays. Users must coordinate options directly with the ATCSCC.

  1. Intermediate landing. The flight should land at the intermediate airport to provide the delay necessary for the flight to arrive at the CTA. An intermediate landing airport within the arrival ARTCC should not be accepted without coordination and approval from the ATCSCC.
  2. Substitution of flights.
  1. Users are permitted to exchange and substitute CTAs congruent with CDM agreements concerning substitutions. The ATCSCC may deny substitution requests when:
  1. AARs are varying rapidly.
  2. Workload necessitates.
  3. Deemed appropriate by the NOM/NTMO.
  1. The ATCSCC must:
  1. Ensure that when flights are traded, the delay factor is equal to the original delay factor after the trade/substitution has been completed.
  2. Document substitutions.
  3. Transmit an ATCSCC advisory when substitutions are suspended and include an estimated time when substitutions will resume.
  1. VFR flights requesting an IFR clearance to a GDP airport should be handled as follows:
  1. DAS. Assign a delay from the DAS table.
  2. GAAP. Call the ATCSCC for a time.
  1. Aircraft requesting to remain VFR will be at the discretion of the terminal facility with the GDP, if they can be accommodated without additional delay to IFR aircraft, except in unusual circumstances; for example, emergency, MEDEVAC.