Skip to content

Ground Delay Management

Overview

Managing the flow of traffic is not just limited to sequencing in the air! Flow Management techniques can be applied to aircraft on the ground to minimise delays in the air and reduce congestion.

In real life, controllers rely on Airport Collaborative Decision Making (A-CDM) to coordinate and plan aircraft movements across the country, and there are multiple dedicated flow controllers and operations analysts to ensure efficiency on a daily basis. On VATSIM we can apply techniques such as pushback management, ground delays, and departure sequencing to evenly distribute workload amongst controllers and to ensure every pilot has an enjoyable experience during our busiest events.

Pushback Requests on ACD

During busy events, such as Milk Run Monday, the SMC controller may end up with a much higher workload than the ACD controller. To mitigate this, some airports have local SOPs that allow for pushback requests to be done on ACD frequency, to balance the workload.

Important

The 'Pushback Requests on ACD' procedure is currently limited to Brisbane, Melbourne, Perth, and Sydney.

At Sydney, the role of ACD in the procedure listed below is performed by a dedicated controller, named Sydney Coordinator. Where a separate Coordinator controller is not online, the role may be performed by ACD instead.

Implementing the Procedure

Note

This procedure is relevant to pushback requests on ACD and the use of Sydney Coordinator. When Sydney Coordinator is active, replace all references to ACD below with Coordinator.

To commence the procedure:

  1. SMC and ACD coordinate to implement the procedure, due to high SMC workload.
  2. SMC coordinates with ADC in order to have the ATIS updated (see each aerodrome's page).
  3. ACD places the STANDBY FOR GROUND bar in the Cleared Bay in OzStrips.

Phraseology

ML SMC -> ML ACD: "It's getting quite busy. Happy to implement Pushback requests on your frequency?"
ML ACD -> ML SMC: "Understood, affirm"
ML SMC -> ML ACD: "Thanks, I'll talk to Tower"

ML SMC -> ML ADC: "Can we please get ALL DEPARTURES MUST REQUEST PUSH BACK ON 127.2 on the ATIS?"
ML ADC -> ML SMC: "Wilco"

Processing each Aircraft

To operate with pushback requests on ACD:

  1. When ACD has finished issuing an airways clearance, they will remind pilots to "Contact me when ready for pushback/taxi".
  2. When a pilot requests pushback, ACD will assess their priority based on apron congestion and number of aircraft in the queue (see Queue Management).
  3. ACD will either instruct them to standby for Ground (not contact), or remain on the ACD frequency if a delay is required.
  4. If an aircraft is instructed to 'standby for Ground', ACD will move the strip below the Standby for Ground bar in the Queue section of the Cleared Bay in OzStrips, to denote they are awaiting pushback approval.
  5. When SMC has adequate space on the aprons, taxiways, and holding points, they will issue pushback/taxi to the next aircraft in line by scanning the Cleared Queue bay.

The decision whether or not to send an aircraft to SMC or hold them on the ACD frequency should be made in accordance with the Queue Management techniques.

Important

If SMC needs to reduce the pushback rate due to congestion at the holding points or excessive workload, ACD should be informed without delay, and instructed to hold all departures on their frequency. This will stop aircraft being told to 'standby for ground' on the SMC frequency. Remember to cancel this requirement when congestion eases.

Phraseology

VOZ543: "Melbourne Delivery, VOZ543, PDC read back"
ML ACD: "VOZ543, Melbourne Delivery"
VOZ543: "DOSEL2 departure, squawk 1336, bay E8, VOZ543"
ML ACD: "VOZ543, contact me when ready for pushback"
VOZ543: "Wilco, VOZ543"
...
VOZ543: "Melbourne Delivery, VOZ543, bay E8, request pushback"
ML ACD: "VOZ543, standby for ground 121.7"
VOZ543: "Standby for ground 121.7, VOZ543"
...
ML SMC: "VOZ543, Melbourne Ground, pushback approved."

When a separate Sydney Coordinator controller is online, pilots should be instructed to contact that controller after reading their airways clearance back.

Tip

If an aircraft is instructed to standby for ground but there is still a small delay expected on SMC (i.e. busy event or taxiway congestion), it may be beneficial to inform the pilot to prevent them from contacting SMC.

E.g. "VOZ543, it's quite busy at the moment, standby for ground 121.7, they'll get to you when they can"

If a delay is required prior to transferring an aircraft to SMC, provide an estimated delay value to the pilot or advise them of their position in the queue.

Phraseology

VOZ543: "Melbourne Delivery, VOZ543, bay E8, request pushback"
ML ACD: "VOZ543, estimated delay 10 minutes, remain this frequency."

Tip

Remember that the bottom aircraft represents the front of the queue.

Queue Management

To reduce SMC workload, ACD should not allow more than three aircraft to be awaiting pushback or taxi on the SMC frequency. When three aircraft are already queued on the SMC frequency, any additional aircraft should be told to remain on the ACD frequency and informed of their position in the queue or approximate delay (if known). These aircraft should be placed in the Cleared Bay Queue, above the Standby for Ground bar.

ACD Ops with OzStrips

Pushback Requests on ACD Ops with OzStrips
Three aircraft are waiting on the SMC frequency (below the Queue bar), and QFA121 and RXA6416 have both requested push/taxi but are being held on the ACD frequency. QFA121 is closer to the bottom, so will be next to be told to standby for SMC.

When SMC moves an aircraft from below the Standby for Ground bar to the Pushback Bay, ACD should instruct the next aircraft in line to standby for ground on the SMC frequency (and move the strip appropriately).

Important

Strips must remain in the strip bay of their current state, even if they are in a queue. For example, if they have received an airways clearance and are in the queue for pushback, they must remain in the Cleared Bay, not the Pushback Bay.

Start Approval

When delays for taxi are excessive (e.g. 15–30 minutes), it may be necessary to include the following ATIS OPR INFO: START APPROVAL RQ. WHEN READY FOR PUSH BACK OR ENGINE START, CTC [POSITION] ON FREQ [FREQUENCY], FOR START TIME.

Tip

Start approvals work best in conjunction with a Coordinator position (or with pushback requests on ACD). The [POSITION] and [FREQUENCY] mentioned above should generally be Sydney Coordinator or ACD.

This will ensure aircraft don't end up burning considerable amounts of fuel and potentially disrupting the latter parts of the flight (with insufficient fuel for lengthy en-route sequencing or holds).

With start approvals in operation, aircraft who do not require pushback will contact Coordinator prior to starting. Coordinator should issue an estimated start time to the aircraft, and contact them when they reach the front of the queue to provide start approval. Aircraft are still expected to report ready to taxi to Coordinator, who will follow the procedure above and tell them to standby for ground the SMC frequency.