Air Accidents Investigation Branch
A Boeing 737-800 completed a takeoff from Runway 09 at Bristol Airport with insufficient thrust to meet regulated performance. The autothrottle (A/T) disengaged when the takeoff mode was selected, at the start of the takeoff roll, and subsequently the thrust manually set by the crew (84.5% N1) was less than the required takeoff thrust (92.8% N1). Neither pilot then noticed that the thrust was set incorrectly, and it was not picked up through the standard operating procedures (SOPs).
This Special Bulletin contains preliminary information on this serious incident, information for pilots and operators of the Boeing 737 Next Generation (737NG) about the A/T disengage occurrence in this event, and the actions the manufacturer expects crews to take should such a disengagement occur.
The investigation continues to examine all pertinent factors associated with this serious incident and a final report will be issued in due course.