When given the instruction ‘cleared for immediate takeoff’, the pilot is expected to act as follows:
- At the holding point: taxi immediately on to the runway and begin a rolling take off without stopping the aircraft. If it is not possible to begin taxiing onto the runway at once or if take off performance calculations mean that a standing start is necessary, then the clearance must be declined
- If already lined-up on the runway: commence take-off without any delay. If this is not possible for any reason, the pilot must advise the controller immediately.
The purpose of issuing clearances for an immediate takeoff is usually to improve runway occupancy. This can apply to a runway being used only for take offs or in mixed mode use (for both for takeoffs and landings).
According ICAO Standards and Recommended Practices (SARPS), in the interest of expediting traffic, a clearance for immediate take-off may be issued to an aircraft before it enters the runway. On acceptance of such clearance the aircraft shall taxi out to the runway and take off in one continuous movement. (ICAO Doc 4444, 7.9.3 Take-off clearance)
Controllers who issue instructions to a departing aircraft to line up and wait in the expectation that the subsequent take off will be an 'immediate' one are advised to add "be ready for an immediate departure" to the line up instruction. This gives the pilot an opportunity to decline the instruction if they anticipate that they may not be able to accept an immediate take off clearance.
Before issuing immediate takeoff clearance to an aircraft the controller should consider the likely time the aircraft will need to commence its takeoff roll - whilst a short haul twin jet would need 30 seconds on average, a fully loaded wide body airliner on a 12-14 hour trip would need more time, and larger engines also take longer to spool up. Also, the controller should consider how quickly and by what route the aircraft could clear the runway if instructed to do so due to non-compliance with the immediate takeoff clearance.
Controllers should be prepared to change their traffic sequence plan in a shortage of time in case of unexpected aircraft non-compliance with the immediate takeoff clearance (e.g. stopping on the runway) . Such change to the controller's initial plan may include, as appropriate:
- cancelling the clearance before the aircraft moves onto the RWY;
- instructing the aircraft to clear the runway;
- de-conflicting the takeoff from a go around in the air;
- issuing of 'stop takeoff' instruction to the departing aircraft that has commenced the take-off roll.
- The procedure should take into account relevant local aerodrome factors and its use should be described in the Manual of Operations of the respective unit.
- In line with normal practice, the word “takeoff” must only be used when issuing the takeoff clearance. In all other reference to a pending takeoff, the word “departure” or “airborne” should be used instead.
- Although an immediate take off clearance given before the aircraft reaches the runway centreline is sometimes referred to as “rolling takeoff”, in official documents such as ICAO Doc 9432, ICAO Doc 4444 (Chapter 12) and UK CAA CAP 413 only the terms “immediate takeoff” and ”immediate departure” are used.