Aviation safety investigations & reports

Flight control systems involving a The Boeing Company 737-377, VH-CZJ, Alice Springs, Aerodrome, NT on 21 July 1998

Investigation number:
Status: Completed
Investigation completed


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When the copilot rotated the aircraft through 17 degrees on the way towards the lift off body angle of 19 degrees the stick shaker activated. Concurrent with the stick shaker activation, the leading edge flaps extend light on the forward panel extinguished and the amber leading edge flaps transit light illuminated. As soon as the stick shaker activated the rotation was stopped. Almost immediately the leading edge flaps transit light extinguished, the leading edge flaps extend light illuminated, and the stick shaker stopped. The activation period was very brief and occurred at approximately 174 knots. The takeoff and climb were continued normally and no other discrepancies were noted. Maintenance investigation disclosed that one of the leading edge slat position micro switches had failed. The failure of the switch caused the logic system to sense that the leading edge slats were retracted rather than extended. This resulted in the stall warning system being reset and the stick shaker to activate at normal takeoff speeeds. The operator advised that the manufacturer is considering a change that will ensure that failure of only one switch is insufficient to cause the system to be reset.
Download Final Report
[Download  PDF: 13KB]
General details
Date: 21 July 1998   Investigation status: Completed  
Time: 18:15 CST    
State: Northern Territory   Occurrence type: Flight control systems  
Release date: 18 August 1998   Occurrence category: Incident  
Report status: Final    

Aircraft details

Aircraft details
Aircraft manufacturer The Boeing Company  
Aircraft model 737-377  
Aircraft registration VH-CZJ  
Sector Jet  
Damage to aircraft Nil  
Departure point Alice Springs NT  
Destination Unknown