London City Airport has revised its procedures following a serious airprox incident involving a Turkish Airlines Boeing 777-300ER and an executive jet which mistakenly climbed above its cleared level on departure.
Investigators have highlighted 21 occasions in the past six years in which aircraft departing City have exceeded the 3,000ft altitude 'step' contained in the airport's standard outbound tracks - a third of them resulting in loss-of-separation events.
As a result of the incident with between the 777 and a Cessna Citation 525 jet, on 27 July last year, the UK's Air Accidents Investigation Branch recommended that the airport remove all 'step climb' procedures and, to avoid confusion, fix all departure tracks to terminate at 3,000ft.
New communications procedures have been implemented at City, the AAIB says, which are designed to ensure that crews understand the requirement to level off at 3,000ft.
In a statement London City's operator says that it has "thoroughly reviewed" the incident report and instigated procedural changes which "comply" with the AAIB's safety recommendations.
While the Citation had been cleared to climb to 3,000ft on departure, the crew erroneously read back a clearance to 4,000ft, which went uncorrected by air traffic control.
As the aircraft took off to the west, and turned north, it came into conflict with the 777 which had been cleared to turn south and descend also to 4,000ft.
While the 777's collision-avoidance system transmitted resolution advisories to descend, the crew "did not respond to [the advisories] in time to affect the geometry of the incident".
The AAIB stresses that, as a result, the conflict was not resolved by the collision-avoidance system, and has recommended that Turkish Airlines improve its training.
Investigators state that the aircraft were on a near-reciprocal heading, at about 0.5nm distance, with a vertical separation of 100-200ft. Weather conditions were clear enough to allow the Citation crew to obtain visual contact with the 777 and adjust the jet's flightpath to resolve the conflict.
Source: Air Transport Intelligence news
