Ground Delay Program

Overview

Ground Delay Programs (GDP) are implemented to control air traffic volume to airports where the projected traffic demand is expected to exceed the airport's acceptance rate for a lengthy period of time. Lengthy periods of demand exceeding acceptance rate are normally a result of the airport's acceptance rate being reduced for some reason. The most common reason for a reduction in acceptance rate is adverse weather such as low ceilings and visibility.

How It Works

Flights that are destined to the affected airport are issued Controlled Departure Times (CDT) at their point of departure. Flights that have been issued CDTs are not permitted to depart until their Controlled Departure Time. These CDTs are calculated in such a way as to meter the rate that traffic arrives at the affected airport; ensuring that demand is equal to acceptance rate. The length of delays that result from the implementation of a Ground Delay Program is a factor of two things; how much greater than the acceptance rate the original demand was, and for what length of time the original demand was expected to exceed the acceptance rate.

Legend

ARPT: Airport for which the Ground Delay Program has been issued.

START: The time, in Universal Coordinated Time (UTC), that the Ground Delay Program will start.

END: The time, in Universal Coordinated Time (UTC), that the Ground Delay Program will end.

Traffic that was originally scheduled to arrive at the affected airport between the program's Start and End time will be issued delay times.

FACILITIES: Indicates which traffic is included in the program. Traffic departing from airports under the jurisdiction of the listed facilities will be issued delay times. See Tier Info for an explanation and graphical representation of jurisdictions.

REASON: The reason that the Ground Delay Program had to be implemented. Common acronyms used in this field are:

AVG: The average delay, in minutes, that has been issued to affected flights.

AAR: The Airport Acceptance Rate. The number of arrivals that an airport is capable of accepting each hour.

PR: The Acceptance Rate that the ATCSCC Program Specialist determines is necesary to minimize the delay.

Example

In this example, flights departing from all airports with a destination of Boston, that were originally scheduled to arrive at Boston between 1800 and 2200, will be issued delays. The average delay will be 41 minutes. The Ground Delay Program was issued because low ceilings and visibility have reduced Boston's acceptance rate (AAR) to 40.

Ground Stop

Overview

Ground Stops are implemented for a number of reasons. The most common reasons are:

• To control air traffic volume to airports when the projected traffic demand is expected to exceed the airport's acceptance rate for a short period of time.
• To temporarily stop traffic to allow time for the implementation of a longer-term solution, such as a Ground Delay Program.
• The affected airport's acceptance rate has been reduced to zero.

How It Works

Flights that are destined to the affected airport are held at their departure point for the duration of the Ground Stop.

Legend

ARPT: Airport for which the Ground Stop has been issued.

TIME: The time, in Universal Coordinated Time (UTC), that the Ground Stop is expected to end.

FACILITIES: Indicates which traffic is included in the Ground Stop. Traffic departing from airports under the jurisdiction of the listed facilities will be stopped. See Tier Info for an explanation and graphical representation of jurisdictions.

REASON: The reason that the Ground Stop had to be implemented.

Example

In this example, flights departing from airports that are under the jurisdiction of Chicago ARTCC and Chicago's first tier ARTCCs, with a destination of Chicago, have been stopped. The Ground Stop is expected to end at 1700, and was implemented because snow is being removed from Chicago's runways.

Deicing

Overview

This table indicates airports where aircraft ground deicing is currently occurring.

How It Works

When necessary, prior to departure, aircraft are sprayed with a deicing fluid to remove snow and ice. The ATCSCC monitors airports that have implemented deicing, to ensure that once an aircraft is deiced, it is not subject to traffic management initiatives that might delay it's departure.

Legend

ARPT: Airport.

AAR/ADR: Airport Acceptance Rate/Airport Departure Rate. The Airport Acceptance Rate indicates the number of arrivals that the airport is capable of accepting each hour. The Airport Departure Rate indicates the number of departures that the airport is capable of handling each hour.

TIME: The time, in Universal Coordinated Time (UTC), that the airport started deicing aircraft. The format is HHMM - the characters indicate the time.

Example

In this example, aircraft at Denver are being deiced. The Airport Acceptance Rate is 80 and the Airport Departure Rate is 80. Denver started deicing aircraft at 0124.

Airport Closures

Overview

This table shows airports that are closed.

How It Works

Occasionally, airports are closed by the local airport authority. The most common reason for an airport closure is snow; the snowplows are unable to keep the runways adequately plowed.

Legend

AIRPORT: The airport that is closed.

TIME: The time, in Universal Coordinated Time (UTC), that the airport was closed. The format is MMDDHHmm. MM = Month. DD = Day of the month. HH = Hour of the day. mm = Minute of the hour.

REASON: The reason that the airport has been closed.

REOPEN: The time, in Universal Coordinated Time (UTC), that the airport is expected to reopen. The format is MMDDHHmm. MM = Month. DD = Day of the month. HH = Hour of the day. mm = Minute of the hour.

Example

In the first example, John F. Kennedy international airport was closed on January 10th at 1350 UTC because of snow. It is currently not known what time John F. Kennedy international airport is expected to reopen.

In the second example, Newark international airport was closed on January 10th at 1200 UTC because of snow. Newark is expected to reopen on January 10th at 2200 UTC.

Delay Information

Overview

This table shows airports that are currently experiencing delays.

How It Works

Terminal facilities are required to report delays of 15 minutes or more to the Air Traffic Control System Command Center (ATCSCC). Delays are tracked in 15 minute increments. Delay times are preceded with either a '+' or a '-' to indicate that the delays are increasing or decreasing. Because the delays are tracked in 15 minute increments, a single delay entry actually represents a time range. For example, an entry of +15 indicates that delays are greater than 15 minutes but less than 30 minutes and are increasing. An entry of -30 indicates that delays are less than 30 minutes but greater than 15 minutes and are decreasing. Normally delays of less than 15 minutes are not shown. The one exception to this is when delays for an airport have just gone below 15 minutes. This will be indicated by an entry of -15.

Legend

ARPT: Airport.

AD: Arrival Delays. Arrival traffic is experiencing delays. This usually indicates that arrival traffic is doing airborne holding.

DD: Departure delays. Departure traffic is experiencing delays. Depending on the length of delay, traffic will be experiencing longer than normal taxi times or holding at the gate.

TIME: The time, in Universal Coordinated Time (UTC), that the delay information, for the specified airport, was last updated.

REASON: The reason for the delays.

Example

In the first example, Chicago is experiencing departure delays. Delays are currently less than 45 minutes but greater than 30 minutes and are decreasing. The last delay report was received at 1545. Thunderstorms are the cause of the delays.

In the second example, Newark is experiencing arrival delays. Delays are currently greater than 15 minutes but less than 30 minutes and are increasing. The last delay report was received at 1535. Fog is the cause of the delays.

Runway/Equipment Information

Overview

This table is used to track equipment outages and construction that may result in air traffic delays.

Legend

FACILITY: The airport or equipment that is experiencing problems.

DESCRIPTION: A brief description of the problem.

Example

Precision Runway Monitor (PRM) Utilization

Overview

This table shows airports whose AAR (Airport Acceptance Rate or Airport Arrival Rate) is being closely monitored while PRM approaches are being conducted.

How It Works

Precision Runway Monitor (PRM) provides controllers with high precision secondary surveillance data for aircraft on final approach.  When in use, Precision Runway Monitor allows controllers to use reduced separation between aircraft making approaches to parallel runways that have extended centerlines separated by less than 4,300 feet.  This reduced separation allows for an increased Airport Acceptance Rate (AAR).

Legend

AIRPORT: The airport whose AAR is being monitored.

START: The date and time, in Universal Coordinated Time (UTC), that the AAR monitoring started at this airport. The format is Mon DD, HHmm. Mon = Month abbreviation. DD = Day of the month. HH = Hour of the day. mm = Minute of the hour.

END: The date and time, in Universal Coordinated Time (UTC), that the AAR monitoring stops at this airport. This is an optional field. If there is a value, its format is Mon DD, HHmm. Mon = Month abbreviation. DD = Day of the month. HH = Hour of the day. mm = Minute of the hour.

AAR: The AAR (Airport Acceptance Rate or Airport Arrival Rate) in effect at this airport during the interval between START and END.

Example

In this example, Dallas/Fort Worth international airport was being monitored to record its AAR from April 1 at 2200 UTC until April 2 at 0330 UTC. During that time, the Airport Acceptance Rate was recorded as being 125 aircraft per hour.

Flight Check Information

Overview

This table shows airports that are scheduled for a flight check.

How It Works

Periodic inspections are made of navigational aids in the National Airspace System (NAS). Some of these inspections are done by specially instrumented aircraft. In order for the flight check instruments to make accurate measurements, certain phases of the flight check must not be interrupted. Because of this, flight inspections can cause minor air traffic delays.

Legend

AIRPORT: The airport that will be flight checked.

ZULU DATE/TIME: The date and time, in Universal Coordinated Time (UTC), that the airport is scheduled to receive a flight check.

LOCAL TIME: The time, in local time, that the airport is scheduled to receive a flight check.

DESCRIPTION: A brief description of what will be checked.

Example

In this example, Seattle is scheduled for a flight check on the 22^nd of November at 2100 UTC, 1300 local time. The flight check aircraft will be checking the Approach Lighting System for Runway 34 Right.

Reported GPS Anomalies

Overview

This table shows reported GPS anomalies, the date and time, aircraft affected, and locations of these anomalies.

Legend

Location (City, ST): The general geographic area affected.

Date and Time: The date and time, in Universal Coordinated Time (UTC), that the anomalies are expected to occur.

Lat/Lon, Altitude and Affected Airspace: The exact Latitude/ Longitude that is affected.

Aircraft Type: A brief description of the type of aircraft that are affected.

Confirmed: In this case, "Confirmed" refers to an action taken by the FAA to validate the presence of a GPS anomaly.  Validation is accomplished by one or more of the following actions:

1. Airborne flight evaluation
2. Identification of interference source
3. Reports from more than one aircraft utilizing an FAA certified GPS receiver (TSO C-129).

Example

Scheduled DoD Testing

Overview

This table shows scheduled DoD testing of known GPS anomalies, the date and time, locations of these anomalies, and a detailed information section.

Legend

Geographic Area: The general geographic area affected.

Date and Time: The date and time, in Universal Coordinated Time (UTC), that the anomalies are expected to occur.

Affected Area and Details: The exact Latitude/ Longitude that is affected.

This information is for planning purposes only. An official U.S . NOTAM will be issued within 72 hours of the actual test starting time if it is not canceled.