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General

The Role of Coordination

Coordination helps controllers stay aware of aircraft that are about to enter their jurisdiction and ensure they will operate in a predictable manner, which allows for easier planning of sequencing and separation. Controllers must engage in constant communication to resolve potential conflicts, hand off aircraft, and maintain the integrity of established traffic flows. In high-density airspace with multiple sectors, controllers must often rely on coordination with adjacent units to address traffic complexities that cannot be resolved within a single sector.

When receiving a coordination call, respond by stating your position. If you are busy, ask the other controller to standby. If the delay will be significant, inform them that you will call back. Each instruction, clearance, or change must be verbalized once by each controller to confirm understanding. If multiple changes are discussed and not yet verbalized by both parties, a readback is required.

Standardised operating procedures and letters of agreement (LoA) define many of these handover conditions, detailing the required flight levels, routing, and speed constraints for transferring aircraft. However, real-time adjustments are often necessary due to weather changes, unexpected congestion, or airspace limitations. Effective coordination ensures that all necessary deviations are communicated and agreed upon between controllers.

Principle of Receiving Unit Control

A core concept in air traffic management is that "the receiving unit sets the entry conditions." This means the sector accepting an aircraft determines the required altitude, speed, and routing.

For instance, if Sector 1 hands off to Sector 2, and Sector 2 mandates aircraft to enter at FL290, speed 280 knots, and a direct route to a designated waypoint, then Sector X is responsible for ensuring compliance before the transfer. While adjustments and negotiations are always possible, this principle ensures clarity and consistency in traffic handling.

Point-to-Point Coordination

Coordination must follow a point-to-point structure, meaning you can only coordinate with the sector the aircraft is arriving from or going to—no skipping sectors.

Example:
If an ACC controller needs to pass an amended route to an aircraft on the ground, they cannot coordinate directly with GND or TWR if the aircraft is currently under APP’s control. Instead, ACC must coordinate with APP, and it is then APP’s responsibility to pass the coordination down the line as needed.

Best Practices for Effective Coordination

All coordination must be clear and unambiguous. Not all controllers will strictly follow phraseology rules, so when using plain language, ensure both parties fully understand the message.

To ensure smooth coordination, controllers should:

  • Communicate early when standard handoff conditions cannot be met.
  • Negotiate changes proactively to prevent last-minute conflicts.
  • Consider weather impacts, airspace restrictions, and real-time traffic adjustments.
  • Ensure that deviations from agreements are confirmed by both sending and receiving sectors.

Early notification and strategic communication facilitate a smoother workflow and prevent operational disruptions.

Key Considerations

  • Coordination is essential for maintaining a safe and efficient air traffic control system.
  • LoAs provide a structured handover process, but flexibility is needed in dynamic conditions.
  • The receiving sector defines entry conditions, but collaboration ensures adaptability.
  • Timely communication prevents operational bottlenecks and enhances overall traffic management.
  • Controllers should anticipate potential conflicts and adjust accordingly with preemptive coordination.

Types of Coordination

Voiceless Coordination

Certain routes, areas, levels, and airspace have voiceless coordination agreements, meaning no verbal coordination is required. These routes may also have change restrictions, where modifications are not allowed within a specific distance from the sector boundary without prior coordination.

Heads-Up Coordination

Heads-up coordination informs the next sector about an incoming aircraft. The format is:

Controlling Sector → Receiving Sector: "(Position), (Callsign)"
Receiving Sector → Controlling Sector: "(Callsign), (Level)"

Example Phraseology

NOR → SOU: "Via SLK, RAM1234"
SOU → NOR: "RAM1234, F350"

If the assigned level at the transfer of jurisdiction is different from the current CFL, the controlling sector will state:

"Will be assigned (level)."

If the receiving sector requires a different level, they will respond with the updated level.

Example Phraseology with Level Change

NOR → SOU: "Via SLK, RAM1234"
SOU → NOR: "RAM1234, F300 due traffic"
NOR → SOU: "F300, RAM1234"

Once coordination is completed, the aircraft’s level and route are locked in. Any further changes must be recoordinated.

The best time to conduct Heads-Up Coordination is when the aircraft first checks in. There’s no need to delay coordination until just before the transfer.

Boundary Coordination

Boundary coordination is required when an aircraft may deviate within half the applicable separation standard of another sector’s airspace.

This applies when an aircraft is within:

  • 500 ft vertically
  • 2.5 NM laterally for enroute (ENR)
  • 1.5 NM laterally for approach/tower (APP/TWR)

Boundary coordination ensures the adjacent sector is aware of the aircraft and can apply restrictions if necessary. The format is:

Controlling Sector → Boundary Sector:

"For Ident, (Position), (Callsign), (Details as required)"

Boundary Sector → Controlling Sector:

"(Callsign), (Restriction)"

Example Phraseology

SOU → NOR: "For Ident, overhead SAK, RAM12, do you have any restrictions on descent?"
NOR → SOU: "RAM12, No restrictions on descent."

The Boundary Sector may omit the restriction and simply read back the callsign. This confirms that no vertical or lateral restrictions apply.

Example Phraseology with Omission

WES → EAS: "For Ident, west of RAVMA, AB123"
EAS → WES: "AB123"

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