¶ Coordination Guide
Coordination is an essential part of air traffic control operations, ensuring that relevant information and clearances are exchanged between control positions in a timely and unambiguous manner. It allows controllers to agree on matters such as transfer of control, routing, levels, restrictions, and other operational information affecting aircraft under their responsibility.
¶ Definitions
- Verbal coordination — Coordination conducted by voice or text using tools such as VACS, Discord, or EuroScope private messages.
- System coordination — Electronic coordination carried out through ATC software such as EuroScope or CoFrance.
- Approval request — A request for agreement to deviate from established procedures or conditions, for example using a routing different from that specified in the LoA.
- Departure release — Authorization issued by the relevant radar controller to the aerodrome controller before an aircraft may depart.
- Transfer of control — The transfer of responsibility for providing air traffic control service to an aircraft.
- Transfer of communication — The process of instructing an aircraft to change to the frequency of the next unit or sector.
- Downstream sector — The sector to which traffic is being transferred.
- Upstream sector — The sector from which traffic is being received.
¶ Transfer of Control and Communication
¶ Transfer of Control
Transfer of control takes effect at the applicable transfer of control point. This is normally the point at which the aircraft’s trajectory crosses the boundary between two adjacent sectors, unless a different point or condition is specified in the relevant Letter of Agreement (LoA) or local procedure.
Transfer of control and transfer of communication are separate processes. The transferring controller remains responsible for the aircraft until the transfer of control takes effect, even if communication has already been transferred to the receiving sector or unit.
¶ Transfer of Communication
Transfer of communication shall be carried out in accordance with the applicable LoA or local procedures. It normally takes place before the transfer of control point is reached, allowing the aircraft to establish communication with the receiving sector or unit in advance of the transfer of responsibility.
¶ Verbal Coordination
¶ Principles
Verbal coordination should be concise, clear, and limited to the information necessary for the coordination. It may be conducted directly between controllers using VACS or through the appropriate Discord coordination channel.
Controllers shall identify their position when establishing verbal coordination. The initial call should follow the same principle as an aircraft’s first contact with ATC: state the callsign of the position being contacted first, followed by your own callsign.
Any coordination proposal or request requiring agreement shall be acknowledged with a complete readback by the receiving controller to confirm that the information has been correctly understood.
¶ Phraseology
The following standard format should be used for verbal coordination to ensure that requests are clearly understood and correctly acknowledged.
🎧 [Receiving Sector] [Own Sector]
📞 Go ahead for [Receiving Sector]
🎧 [Coordination Request]
📞 Approved/Unable/Roger/Other Answer
🎧 [Readback]
A practical coordination example between PAR_AR_CTR and LFPG_S_APP is provided below.
🎧 De Gaulle Approach South, Paris AR.
📞 Go ahead for De Gaulle Approach South.
🎧 Approval request, AFR42DT inbound OKIPA, can you accept descending to FL180?
📞 AFR42DT is accepted descending FL180.
🎧 AFR42DT is accepted descending FL180. Merci!
A practical visual and audio guide to radar coordination is available here. The material was created by McChester from vACC Austria.
¶ Release Procedure
A release allows the receiving sector to issue certain instructions to an aircraft before the normal transfer of control takes effect, provided that communication has already been transferred.
A release may be coordinated verbally or, where available, through the relevant CoFrance coordination tools.
¶ Definitions
- Released for Climb — authorizes the receiving controller to climb the aircraft before the transfer of control point.
- Released for Descent — authorizes the receiving controller to descend the aircraft before the transfer of control point.
- Released for Turn — authorizes the receiving controller to alter the aircraft’s track before the transfer of control point, normally by no more than 45°.
¶ Use of Releases
The release procedure is used when the receiving controller needs to take limited control action before the aircraft formally enters their area of responsibility.
Typical situations include:
- An aircraft makes a request shortly before reaching the sector boundary. Rather than coordinating a late change, the transferring controller may hand the aircraft over with an appropriate release, allowing the receiving controller to accommodate the request without delay.
- A potential conflict exists shortly after the sector boundary. A release allows the receiving controller, who is responsible for resolving the conflict, to issue the necessary instruction before the transfer of control point. This also helps ensure that the relevant traffic is handled on the same frequency.
¶ Controller Handover
Controller handovers are a form of verbal coordination used to transfer responsibility from one controller to another. Unlike operational coordination between sectors, the handover may be conducted in plain language, provided that the current traffic situation and any relevant non-standard information are clearly communicated.
¶ Handover Procedure
- The relieving controller should connect using a relief callsign before taking over the position. This may be done by adding an additional underscore where possible, or by inserting a number into the sector callsign when the callsign character limit is reached. For example,
LFRR_EST_CTRmay be relieved using a callsign such asLFRR_E1T_CTR. This allows the relieving controller to prepare the frequency and review the current traffic situation within the area of responsibility. - When traffic conditions permit, the current controller shall brief the relieving controller on the traffic situation, coordination in progress, and any non-standard or relevant operational information.
- The relieving controller shall acknowledge the briefing and confirm when ready to assume the position.
- Once the handover is complete, the current controller shall state “Your Frequency”. The relieving controller shall acknowledge with “My Frequency”, confirming the transfer of responsibility for the frequency.
Certain items, such as clearance flags or ground states shown in the departure list, may not synchronize correctly between controllers. Before completing the handover, it is good practice for the current controller to refresh or update these items once the relieving controller confirms readiness.
¶ Logging Off with an Upper Station Online
Before logging off, the controller assuming responsibility under the top-down principle shall be informed of the current traffic situation using the handover procedure described above.
Where appropriate, the receiving controller may cross-couple the relevant frequencies in their audio client using XA or XCA. This may avoid the need to transfer aircraft individually to another frequency during the handover.
Frequency cross-coupling should only be applied once the operational handover has been completed, as it combines the associated frequencies into a single transmission and reception environment.
¶ Logging Off with Lower Stations Online
Before logging off while underlying positions remain online, the controller shall inform the affected lower stations that the sector is closing.
For example, when an Area Control position closes while an Approach position remains online, the Approach controller shall be informed so that aircraft are not transferred to a frequency that is no longer active.
This coordination is essential to prevent aircraft from being instructed to contact an inactive frequency.