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Coordination between Units

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Each pair of units exchanges different information, because each needs different things from the other. The tables below list what ICA 100-37 requires to be passed in each direction. On the network, much of this already arrives through the tag and the flight plan. Coordinate in the chat what the tag does not show: flight plan changes, delays, holds, missed approaches and restrictions.

Between ACCs, and between sectors of an ACC

The flight plan information needed for coordination passes from one unit to the next as the flight progresses, sufficiently in advance for the accepting unit to analyse it1. Between sectors of the same unit, exchange information on2:

  • every aircraft transferred from one position to another;
  • aircraft operating near the boundary between sectors that may affect traffic in the neighbouring sector;
  • aircraft whose control has been delegated to another position, and the others affected by that delegation.

When part of an area is so narrow that there is no time to control the traffic crossing it, the units may agree on a direct transfer between the two units at either end, informing the intermediate unit3.

ACC-CW: "Estimate VRG 3256, Cuiabá to Guarulhos, FL 330, VARGA at 55."

Between ACC and APP

Who decides what

The ACC Source
Specifies the take-off time, when needed to coordinate the departure with its traffic or to separate aircraft on the same route. If it does not, the APP may do so 4
Specifies the clearance expiry time, if a delayed departure could interfere with traffic. If the APP sets its own, it can never be later than the ACC's 4
When weather conditions require an approach sequence, clears arrivals to holding points, with holding instructions and an expected approach time 4

What the ACC tells the APP

Information Source
Identification, type and point of departure of arrivals 5
Proposed level and estimated time over the holding fix, or the actual time if the aircraft is transferred after reaching the fix 5
Expected approach time given to the aircraft 5
That the aircraft has been cleared to contact the APP, or has been transferred, with time and conditions if necessary 5
Expected delay to departures due to congestion 5

Arrival information is sent at least 15 minutes before the estimated time of arrival and revised whenever necessary6.

What the APP tells the ACC

Information Source
Lowest level available at the holding point that can be made available to the ACC 7
Average interval between successive approaches 7
Revision of the expected approach time when the one calculated by the APP differs by 5 minutes or more 7
Time of arrival over the holding point when it differs by 3 minutes or more from the calculated one 7
IFR cancellations that affect the holding levels or expected approach times of other aircraft 7
Take-off times from aerodromes without a TWR 7
Delays and overdue aircraft 7
Missed approaches 7

APP-SN: "Lowest level available at STM VOR, FL 070."

ACC-BL: "Roger, TAM 3235 descending to FL 070."

Between APP and TWR

Who decides what

Rule Source
The APP retains control of arrivals until they have been transferred and are in communication with the TWR 8
After coordinating with the TWR, the APP may release arrivals to visual holding points, where they remain until further clearance from the TWR 9
The APP may authorize the TWR to clear a take-off, provided the TWR observes separation from arrivals 10
The TWR only relays a special VFR clearance after obtaining it from the APP 11

The third rule is the departure release. In a TMA with arrivals, the tower does not let an IFR flight take off without the APP knowing and agreeing, because the departure will enter the airspace where the arrivals are.

What the TWR tells the APP

Information Source
Landing and take-off times 12
That the first aircraft in the sequence is in communication with the TWR, in sight, and is likely to land 12
Delays and overdue aircraft 12
Aircraft that are essential traffic for the APP's aircraft 12

What the APP tells the TWR

Information Source
Expected time and proposed level of arrival over the aerodrome, at least 15 minutes before landing, when flight time allows. For aerodromes less than 15 minutes' flight away, as early as possible 13
That it has cleared the aircraft to contact the TWR and that the TWR will take over control 13
Expected delays to take-offs due to congestion 13
The arrival sequence and the instructions and restrictions given to the arrivals 14

APP-RF: "PT ITU with landing priority, ambulance aircraft number 1 on approach, PT CTA number 2."

TWR-RF: "Roger, PT ITU number 1, PT CTA number 2."

Between TWR and ground

The transfer between tower and ground follows the points on the previous page: after vacating the runway, on arrival, and at the holding point, on departure. Agree between the two positions anything that differs, such as a runway crossing during taxi or an intermediate holding position. See TWR and ground.

  1. ICA 100-37, Art. 824. See ICA 100-37. ↩

  2. ICA 100-37, Art. 852. ↩

  3. ICA 100-37, Art. 836. ↩

  4. ICA 100-37, Art. 838, items II to VI and sole paragraph. ↩↩↩

  5. ICA 100-37, Art. 842. ↩↩↩↩↩

  6. ICA 100-37, Art. 843. ↩

  7. ICA 100-37, Art. 841. ↩↩↩↩↩↩↩↩

  8. ICA 100-37, Art. 844. ↩

  9. ICA 100-37, Art. 845. ↩

  10. ICA 100-37, Art. 846. ↩

  11. ICA 100-37, Art. 847. ↩

  12. ICA 100-37, Art. 850. ↩↩↩↩

  13. ICA 100-37, Art. 851 and sole paragraph. ↩↩↩

  14. ICA 100-37, Art. 996. ↩