Created Thursday, Feb 8th 2024 11:55Z, last updated Thursday, Feb 8th 2024 11:55Z
A West Atlantic Boeing 737-300 freighter, registration G-JMCU performing flight NPT-28E from Aberdeen,SC to East Midlands,EN (UK) with 2 crew, departed Aberdeen's runway 34 with flap setting 1 instead of 5 as planned. The crew noticed the wrong flap setting during flap retraction and continued to East Midlands for a safe landing without further incident.
On Feb 8th 2024 the British AAIB released their final bulletin into the occurrence rated a serious incident stating, that the actual takeoff parameters were sufficient for the flaps 1 takeoff, and concluding the probable causes of the serious incident were:
An incorrect flap selection was made and not detected before takeoff. A combination of poor weather conditions and time pressure may have influenced the pilot’s performance. It is necessary to check the actual flap position set, because the green configuration light indicates only that flap more than zero is set.
The AAIB analysed:
The poor weather conditions introduced several distractions on the fight deck before departure. The application of the SP 16 procedure put the pilots out of their normal sequence for setting takeoff flap. The task of taxiing in reduced visibility on a narrow taxiway would have taken more mental capacity than normal, and was likely exacerbated by the time pressure introduced by the worsening environmental conditions. It is possible the co-pilot reverted to the motor memory of selecting one flap detent, which was correct on the ATR 72 he had recently flown.
The commander visually confirmed the LE flap ext light was illuminated once lined up on the runway, but did not confirm the actual position of the flaps on the indicator.
Flap 1 is an allowable takeoff setting for a Boeing 737-300 and would not result in any further annunciations. There was therefore nothing to alert the pilots to the incorrect flap setting other than to check it themselves.
In this event, completing the takeoff with flap 1 did not have any effect on the safe conduct of the flight. In other circumstances where the takeoff performance was limited, such as an increased aircraft weight, reduced runway length or less favourable environmental conditions, there may have been a greater risk to the safety of the aircraft.
