Thanks Basil, quite possibly, although initial reading of the report that may not quite fit? Admittedly the initial bulletin doesn't state either way.
The sequence of events was:
- Approach with AP On with Heading Select and Altitude Tracking modes selected
- Decision was made to discontinue, and the pilot then manually turned the aircraft using control inputs. So he was manually making control inputs before the lightning strike, whilst the AP was still engaged. (I'm interested though, on a type like the Saab 2000, if the approach was discontinued and needed manual control inputs like a heading change, would a crew disconnect the AP first or not? Maybe he thought the manual control inputs had auto-disconnected the AP at this stage in the flight?)
- As rolling out, lightning strike and pilot pulled back in a climb in response and (tried) to manually add in more up-trim to boot. Initially he "won" against the AP, but it progressively added more and more down-trim to get back to its altitude setting
The very first bit of the subsequent advice published by Saab, in response to the incident, to operators is interesting too, as it implied that some operators/pilots may not know that manual control inputs or main trim switch inputs do not disengage the AP on this type. That in turn implies that some pilots may "instinctively" think that manual control inputs disable the AP and they don't necessarily have to hit the Disconnect button?
"Manual control inputs will not cause the autopilot to disengage and the main trim switches are disabled when the autopilot is engaged. Consequently, operation
of the main pitch trim switches will not have any effect on aircraft trim nor cause the autopilot to disengage.
Disengaging the autopilot is normally done by pushing the disconnect button on either control wheel..."