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Approval Request Procedure
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Approval request is a coordination procedure when an upstream controller asks their downstream colleague to accept a plan that is not a subject to silent approval (i.e. is considered to be approved unless an explicit objection is made). The transferring (upstream) controller must keep the aircraft within their area of responsibility until the request is approved or an alternative plan is agreed upon. The main uses of this procedure are when the flight time to the boundary is short and therefore, information cannot be passed within the agreed time period or when a deviation from the agreed procedures is necessary. The rationale behind this is that the accepting controller must have enough time to review and assess the situation and come up with an appropriate plan to address it safely.
The applicability of the procedure is described in letters of agreement between neighbouring ATS units or in local instructions (e.g. manuals of operations). This includes the situations for which it applies as well as the relevant parameters. For example, changing the level of a flight at the transfer of control point may only be subject to approval request if done less than X minutes before reaching that point.
There are three major scenarios where the use of an approval request is necessary:
- If the flying time from the departure aerodrome to the boundary of an adjacent control area is less than the time to transmit the necessary information (e.g. an estimate). In this case, the upstream unit should hold the departure until the coordination is completed successfully.
- If an aircraft is in flight and the time to the boundary is less than a specified minimum. In this case the upstream unit should keep the aircraft within its area of responsibility until the request to proceed in the next unit's airspace is approved.
- In the case a change in the current flight plan is necessary (either due to a pilot's request or on the upstream's controller initiative) that affects the downstream ATS unit. Examples of such changes are:
- A change of the coordinated flight level shortly before the boundary (the exact time limit is specified in the letter of agreement or a local procedure)
- A deviation from the flight level allocation scheme (e.g. transferring an aircraft at an opposite level or higher/lower than the standard procedure)
- Clearing the flight to proceed directly to a point in the downstream unit's area of responsibility
- Transferring the control of the aircraft while being vectored (as opposed to flying on own navigation)
Failure to correctly identify the need to perform an approval request as an upstream controller may have undesired results, e.g.:
- Increased worlkoad for the downstream controller (due to the surpirse change of the situation and lack of appropriate plan)
- Loss of Separation
- Airspace Infringement, e.g. the flight entering a military zone.
- Upstream controller: Approval request IVB995 estimated departure from Nearville at 1120
- Downstream controller (accept): IVB995 request approved, FL 150 or below
- Downstream controller (reject): IVB995 unable due restricted area, expect approval at 1130
- Upstream controller: Approval request DVK1208 FL 380 (note: in this example, eastbound levels are to be used according to the letter of agreement)
- Downstream controller (accept): DVK1208 request approved
- Downstream controller (reject): DVK1208 unable due traffic, request FL 370 or FL 390
- Release Procedure
- Transfer of Control
- ATC Unit Coordination
- ATC Team Coordination
- Loss of Separation at Sector Boundaries
- ICAO Doc 4444: PANS-ATM