B757-200
Flight Crew Air Transport Pilot (ATP)
Workload; Troubleshooting; Human-Machine Interface; Confusion
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew FLC Overrode Automation; General Maintenance Action
Aircraft; Procedure; Human Factors
On takeoff out of SNA on the RNAV Noise Abatement Procedure with the autopilot engaged in VNAV the aircraft pitched up and slowed below V2 by about 10 KTS. We disconnected the autopilot and pitched the nose over to regain speed. No stall warning or stick shaker occurred. Subsequently; on flap retraction; we later learned we had a 5-8 KT flap overspeed.
While executing the RNAV Noise Abatement departure at SNA I was distracted from monitoring airspeed momentarily; while we were given ATC frequency change and a new altitude clearance. As my scan returned back to the instruments I saw that we were slow; below V2; with no acceleration or pitch change. We were both confused momentarily as to why speed was slow and no acceleration; I scanned for power problems or the gear not retracted; etc. Engines were normal; and correctly configured; but no acceleration. I turned off the autopilot and advanced the throttles. There was a need for a lot of nose down trim required; which I trimmed to neutral. I was then hand flying the departure but once airspeed was above V2 I re-engaged the right autopilot (our original configuration). We were in the turn and above 5;000 FT at the time. As the aircraft accelerated; I called for flap retraction; on schedule; with the white bug settings. As we continued to accelerate; in the turn; I noticed a 500 FPM descent. I disconnected the autopilot again and hand flew the aircraft. Again; there was a need for a significant amount of trim. Once in trim I engaged the left autopilot. During the cleanup; I noticed very briefly what I thought was an overspeed warning on my PFD (I became aware of a yellow annunciation in the upper left corner of the PFD). I did not fully read it; as it was gone as soon as I saw it. I glanced at the airspeed indicator and at that time was seeing 230 KTS. I did not think anything more of it. While in cruise; the Captain and I discussed the events. We both agreed we had retracted on schedule. I was not sure however if the flaps had fully retracted; or hung up in any way; or were slow to retract; as I was not watching the flap position indicator at the time of flap retraction. We both discounted it as an anomaly and decided to write up the autopilot in the logbook.
Inappropriate and confusing autoflight functions while flying the SNA Runway 19 Noise Abatement Procedure may have resulted in a flap overspeed during the period of time the Flight Crew of the B757-200 contemplated an appropriate response.