Narrative:

On right base I was hand-flying the aircraft in good visual conditions. Several minutes prior to landing; halfway through configuring the aircraft (I believe at flaps 15); I became aware primary stabilizer trim was inoperative. The first officer did a quick overview of circuit breaker; switch positions; etc. And I asked him to try his main stabilizer trim switch. Main trim inoperative; alternate trim worked normally. Configured aircraft for landing slightly early and aircraft trim very manageable and on-speed and in-trim condition for landing. On final I announced my intention to land; and articulated to my first officer my judgment to land while all set up was safer course of action than executing a go-around and exposing the aircraft to 7-10 minutes of flight with malfunctioning main trim and excursion through wide airspeed regime. Also announced I would purposefully keep trim slightly nose-heavy in the event a go-around were necessary. Landed in good trim and on-speed at flaps 28. I committed an error of judgment; however. On self-reflection and critique; any primary flight-control malfunction; no matter how well-handled; constitutes an emergency; and in retrospect we should have formally declared same with ATC. By way of explanation-- not an excuse -- by the time we had the situation sized-up executing the plan; we were on short final and I didn't think advising tower had any value. That was a mistake and in the future will declare a precautionary emergency at the beginning of any situation that qualifies. Malfunctions can get very bad very fast.

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Original NASA ASRS Text

Title: An MD80 primary horizontal trim stabilizer motor failed as the aircraft was being slowed and configured for landing. The Captain continued the approach using alternate trim and landed without notifying ATC; declaring an emergency or completing a checklist.

Narrative: On right base I was hand-flying the aircraft in good visual conditions. Several minutes prior to landing; halfway through configuring the aircraft (I believe at FLAPS 15); I became aware primary stabilizer trim was inoperative. The First Officer did a quick overview of circuit breaker; switch positions; etc. and I asked him to try his main STAB trim switch. Main Trim inoperative; alternate trim worked normally. Configured aircraft for landing slightly early and aircraft trim very manageable and on-speed and in-trim condition for landing. On final I announced my intention to land; and articulated to my First Officer my judgment to land while all set up was safer course of action than executing a go-around and exposing the aircraft to 7-10 minutes of flight with malfunctioning main trim and excursion through wide airspeed regime. Also announced I would purposefully keep trim slightly nose-heavy in the event a go-around were necessary. Landed in good trim and on-speed at Flaps 28. I committed an error of judgment; however. On self-reflection and critique; any primary flight-control malfunction; no matter how well-handled; constitutes an emergency; and in retrospect we should have formally declared same with ATC. By way of explanation-- not an excuse -- by the time we had the situation sized-up executing the plan; we were on short final and I didn't think advising tower had any value. That was a mistake and in the future will declare a precautionary emergency at the beginning of any situation that qualifies. Malfunctions can get very bad very fast.

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.