Narrative:

We had flown this aircraft for three previous legs on our pairing. The first officer's walk-around inspection before this leg did not indicate any problems. At rotation on takeoff the #1 stall warning stick shaker activated. Because all three airspeed indicators showed normal speeds; and our flap/slat configuration was confirmed as normal; we assumed that this was a false stall warning and proceeded to clean up and climb normally. We also saw spurious flight director indications and notified tower that we were unable to fly the RNAV departure for which we had been cleared. They cooperated and gave us radar vectors. We continued on vectors and leveled off at 14;000 feet to troubleshoot. We searched the QRH for a relevant procedure and found none. We contacted dispatch and maintenance control through a radio/phone patch and described the anomalies with the stick shaker and flight directors and also the fact that the autothrottles appeared to drive to the N1 limits for each phase of flight. Maintenance control advised us to continue to our destination and said they believed that the no. 1 stall warning and autothrottles could be placed on MEL there. They gave us the relevant MEL numbers and we consulted the MEL and saw no reason why we could not safely proceed to our destination. Also; after consulting the MEL; and because the stick shaker had been on continuously since rotation and was highly distracting; we pulled the #1 stall warning dc circuit breaker; which shut off the stick shaker. We continued uneventfully to destination with autothrottles off. After arrival; it was discovered that the left aoa [angle of attack] vane was broken and was attached only by the wires to its heating element. However the cause of that damage is unknown.

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Original NASA ASRS Text

Title: A B737-400 Flight Crew experienced continuous inappropriate stick shaker activation after takeoff. They unpowered the system and continued to destination where it was discovered the associated AOA (Angle of Attack) vane had been damaged.

Narrative: We had flown this aircraft for three previous legs on our pairing. The First Officer's walk-around inspection before this leg did not indicate any problems. At rotation on takeoff the #1 stall warning stick shaker activated. Because all three airspeed indicators showed normal speeds; and our flap/slat configuration was confirmed as normal; we assumed that this was a false stall warning and proceeded to clean up and climb normally. We also saw spurious flight director indications and notified Tower that we were unable to fly the RNAV departure for which we had been cleared. They cooperated and gave us radar vectors. We continued on vectors and leveled off at 14;000 feet to troubleshoot. We searched the QRH for a relevant procedure and found none. We contacted Dispatch and Maintenance Control through a radio/phone patch and described the anomalies with the stick shaker and flight directors and also the fact that the autothrottles appeared to drive to the N1 limits for each phase of flight. Maintenance Control advised us to continue to our destination and said they believed that the No. 1 stall warning and autothrottles could be placed on MEL there. They gave us the relevant MEL numbers and we consulted the MEL and saw no reason why we could not safely proceed to our destination. Also; after consulting the MEL; and because the stick shaker had been on continuously since rotation and was highly distracting; we pulled the #1 stall warning DC circuit breaker; which shut off the stick shaker. We continued uneventfully to destination with autothrottles off. After arrival; it was discovered that the left AOA [Angle of Attack] vane was broken and was attached only by the wires to its heating element. However the cause of that damage is unknown.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.