Narrative:

West were air carrier xx from dtw to dca on jun/sun/89. We were climbing to 26,000, and were subsequently cleared to 28,000 by ZOB. I was flying the aircraft, an large transport by hand with the automatic throttles engaged. My copilot accepted the clearance, and dialed the correct altitude into the flight guidance mode control panel, and I continued the climb. As we reached the cleared altitude, I was following the flight director (VNAV) command bars, and expected the automatic throttle (speed mode) to reduce power as I began to push over on the nose. What happened was that, although they did begin to retard, they did so late, and at a pace considerably slower than they usually do, and as a consequence, the nose resisted the push over, and we continued to climb an additional few hundred feet, leveling off at 28,300, and then returning to 28,000. ZOB caught the error and asked us to verify leveling at 28,000 as we were passing 28,100 on the way back to 28,000. We reported that we were. Since I have just returned to the aircraft (2ND trip) after a yr on another, and remembered complete reliability from the flight guidance system, I was surprised enough by this action of the automatic throttles to momentarily question whether we had been cleared a thousand feet higher. A look at the altitude window verified 28,000 was correct, but the hesitancy may have lost me an extra hundred feet on the level off. Moral: eternal vigilance. Contributing factors: last 4 trips have alternated widebody transport and large transport current on both aircraft. And eligible for 'callup' on widebody transport.

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Original NASA ASRS Text

Title: ALT DEVIATION OVERSHOT ALT ON CLIMB.

Narrative: W WERE ACR XX FROM DTW TO DCA ON JUN/SUN/89. WE WERE CLIMBING TO 26,000, AND WERE SUBSEQUENTLY CLRED TO 28,000 BY ZOB. I WAS FLYING THE ACFT, AN LGT BY HAND WITH THE AUTO THROTTLES ENGAGED. MY COPLT ACCEPTED THE CLRNC, AND DIALED THE CORRECT ALT INTO THE FLT GUIDANCE MODE CTL PANEL, AND I CONTINUED THE CLIMB. AS WE REACHED THE CLRED ALT, I WAS FOLLOWING THE FLT DIRECTOR (VNAV) COMMAND BARS, AND EXPECTED THE AUTO THROTTLE (SPEED MODE) TO REDUCE POWER AS I BEGAN TO PUSH OVER ON THE NOSE. WHAT HAPPENED WAS THAT, ALTHOUGH THEY DID BEGIN TO RETARD, THEY DID SO LATE, AND AT A PACE CONSIDERABLY SLOWER THAN THEY USUALLY DO, AND AS A CONSEQUENCE, THE NOSE RESISTED THE PUSH OVER, AND WE CONTINUED TO CLIMB AN ADDITIONAL FEW HUNDRED FEET, LEVELING OFF AT 28,300, AND THEN RETURNING TO 28,000. ZOB CAUGHT THE ERROR AND ASKED US TO VERIFY LEVELING AT 28,000 AS WE WERE PASSING 28,100 ON THE WAY BACK TO 28,000. WE REPORTED THAT WE WERE. SINCE I HAVE JUST RETURNED TO THE ACFT (2ND TRIP) AFTER A YR ON ANOTHER, AND REMEMBERED COMPLETE RELIABILITY FROM THE FLT GUIDANCE SYSTEM, I WAS SURPRISED ENOUGH BY THIS ACTION OF THE AUTO THROTTLES TO MOMENTARILY QUESTION WHETHER WE HAD BEEN CLRED A THOUSAND FEET HIGHER. A LOOK AT THE ALT WINDOW VERIFIED 28,000 WAS CORRECT, BUT THE HESITANCY MAY HAVE LOST ME AN EXTRA HUNDRED FEET ON THE LEVEL OFF. MORAL: ETERNAL VIGILANCE. CONTRIBUTING FACTORS: LAST 4 TRIPS HAVE ALTERNATED WDB AND LGT CURRENT ON BOTH ACFT. AND ELIGIBLE FOR 'CALLUP' ON WDB.

Data retrieved from NASA's ASRS site as of August 2007 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.