What happened
On 13 December 2008, a Boeing 757-2T7, registration G-MONK, was performing a commercial passenger flight from London Gatwick to Innsbruck. During the approach to Gatwick, the aircraft was operating in challenging weather conditions, characterized by high winds and heavy gusts.
While managing the approach, the commander manually deployed the speedbrakes to increase drag and manage the descent rate. However, during the subsequent decision to perform a go-around, the crew failed to retract the speedbrakes. As the aircraft transitioned into the climb, the airspeed decayed significantly. The loss of speed eventually triggered the stick shaker, and the Flight Director pitch guidance disappeared from the primary displays, causing the commander to become disoriented.
Recognizing the loss of situational awareness, the commander handed control to the co-pilot. The co-pilot, who maintained better awareness, lowered the aircraft's nose to recover speed. Once the airspeed had stabilized, the commander regained control and eventually retracted the speedbrakes. The aircraft continued the climb and the situation was stabilized.
The investigation
An AAIB field investigation examined the flight data and cockpit voice recordings. The investigation focused on why the speedbrakes remained extended and why the flight director guidance failed during the maneuver.
Investigators utilized a simulator assessment with a Type Rating Examiner to study the flight dynamics. The assessment revealed that a 15-degree nose-up pitch attitude was adopted during the climb, increasing to 20 degrees while the speedbrakes were still extended. The simulator study also highlighted that the autopilot applied significant nose-up trim during the go-around, creating a high risk of pitch instability when control was transferred between pilots.
Findings
- The crew inadvertently left the speedbrakes deployed during the go-around maneuver.
- The disengagement of the auto-throttle, which occurred when the commander disconnected the autopilot, contributed to the rapid decay in airspeed.
- The commander experienced disorientation due to the disappearance of pitch guidance on the primary flying displays.
- The aircraft's speed decayed to approximately 123 kt, triggering the stick shaker.
- The Boeing 757 aircraft involved lacked a specific cockpit warning for speedbrake extension based on thrust lever position, a feature only present on newer models.