Narrative:

Last leg of 3-DAY trip with a check airman administering my IOE. Aircraft was an medium large transport with CRT flight instruments. The autoplt was engaged and cruising at FL350. Cleared to FL330, I set and armed the altitude and began a vertical speed descent. The check airman and I were discussing some operational situations with the airplane and some of the engineering 'traps' the pilot has to watch for when I looked at my altimeter and saw 32,800' I crosschecked the other two altimeters and confirmed the deviation. The descent continued and the captain joined in the pull and I disengaged the autoplt. The descent continued to 32,400/32,500 before climb could begin. The back pressure was surprisingly high and I began nose up trim. I looked at the pitch trim indicator and was surprised to see it moving back through the 2 degree nose down position. Level off at 33,000 was completed, autoplt engaged, no further events, no comment from ATC. At FL350 cruise mach was .764, don't recall trim indicator. At FL330 cruise mach .764 trim indicator 1-2 units nose up. I have 2300 hours of manufacturer Y medium large transport time. This is my first manufacturer X airplane. I am not impressed with the human engineering. My impression is that it is a good example of 'a collection of afterthought add-on's'. While in cruise using the pms, altitude varies +/-200'. On the first day of my checkout (different check airman) while in performance cruise (pms) the airplane disengaged from altitude hold and was on the way down! Both check airman stated '...it will do these things to you all the time, watch it!' the airplane handles nice, I like hand-flying it. Now I know I cannot trust the advanced (?) engineering of the medium large transport X. After one year of a lock-in I can bid off, color me manufacturer Y. Supplemental information from acn 124082: the aircraft has been certificated to climb or descend at a high rate (exceeding 1000 FPM) during the final 1000' of climb or descent. If a man can't climb or descend at a rate exceeding 1000 FPM during that last 1000', then he also cannot monitor a machine doing the job, decide whether it's going to work or not, and then take necessary corrective action. This act is responsible for more altitude excursions than any other aircraft I know about. Indeed, some of them are because the pilot improperly operated a poorly designed system, but in most instances there is no pilot error involved aside from having a response time that exceeds zero.

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Original NASA ASRS Text

Title: ACR MLG ALT DEVIATION OVERSHOT DURING DESCENT USING AUTO LEVEL OFF THAT FAILED TO CAPTURE AS PROGRAMMED.

Narrative: LAST LEG OF 3-DAY TRIP WITH A CHECK AIRMAN ADMINISTERING MY IOE. ACFT WAS AN MLG WITH CRT FLT INSTRUMENTS. THE AUTOPLT WAS ENGAGED AND CRUISING AT FL350. CLRED TO FL330, I SET AND ARMED THE ALT AND BEGAN A VERTICAL SPEED DSCNT. THE CHECK AIRMAN AND I WERE DISCUSSING SOME OPERATIONAL SITUATIONS WITH THE AIRPLANE AND SOME OF THE ENGINEERING 'TRAPS' THE PLT HAS TO WATCH FOR WHEN I LOOKED AT MY ALTIMETER AND SAW 32,800' I XCHKED THE OTHER TWO ALTIMETERS AND CONFIRMED THE DEVIATION. THE DSCNT CONTINUED AND THE CAPT JOINED IN THE PULL AND I DISENGAGED THE AUTOPLT. THE DSCNT CONTINUED TO 32,400/32,500 BEFORE CLIMB COULD BEGIN. THE BACK PRESSURE WAS SURPRISINGLY HIGH AND I BEGAN NOSE UP TRIM. I LOOKED AT THE PITCH TRIM INDICATOR AND WAS SURPRISED TO SEE IT MOVING BACK THROUGH THE 2 DEG NOSE DOWN POSITION. LEVEL OFF AT 33,000 WAS COMPLETED, AUTOPLT ENGAGED, NO FURTHER EVENTS, NO COMMENT FROM ATC. AT FL350 CRUISE MACH WAS .764, DON'T RECALL TRIM INDICATOR. AT FL330 CRUISE MACH .764 TRIM INDICATOR 1-2 UNITS NOSE UP. I HAVE 2300 HRS OF MANUFACTURER Y MLG TIME. THIS IS MY FIRST MANUFACTURER X AIRPLANE. I AM NOT IMPRESSED WITH THE HUMAN ENGINEERING. MY IMPRESSION IS THAT IT IS A GOOD EXAMPLE OF 'A COLLECTION OF AFTERTHOUGHT ADD-ON'S'. WHILE IN CRUISE USING THE PMS, ALT VARIES +/-200'. ON THE FIRST DAY OF MY CHECKOUT (DIFFERENT CHECK AIRMAN) WHILE IN PERFORMANCE CRUISE (PMS) THE AIRPLANE DISENGAGED FROM ALT HOLD AND WAS ON THE WAY DOWN! BOTH CHECK AIRMAN STATED '...IT WILL DO THESE THINGS TO YOU ALL THE TIME, WATCH IT!' THE AIRPLANE HANDLES NICE, I LIKE HAND-FLYING IT. NOW I KNOW I CANNOT TRUST THE ADVANCED (?) ENGINEERING OF THE MLG X. AFTER ONE YEAR OF A LOCK-IN I CAN BID OFF, COLOR ME MANUFACTURER Y. SUPPLEMENTAL INFORMATION FROM ACN 124082: THE ACFT HAS BEEN CERTIFICATED TO CLIMB OR DSND AT A HIGH RATE (EXCEEDING 1000 FPM) DURING THE FINAL 1000' OF CLIMB OR DSCNT. IF A MAN CAN'T CLIMB OR DSND AT A RATE EXCEEDING 1000 FPM DURING THAT LAST 1000', THEN HE ALSO CANNOT MONITOR A MACHINE DOING THE JOB, DECIDE WHETHER IT'S GOING TO WORK OR NOT, AND THEN TAKE NECESSARY CORRECTIVE ACTION. THIS ACT IS RESPONSIBLE FOR MORE ALT EXCURSIONS THAN ANY OTHER ACFT I KNOW ABOUT. INDEED, SOME OF THEM ARE BECAUSE THE PLT IMPROPERLY OPERATED A POORLY DESIGNED SYSTEM, BUT IN MOST INSTANCES THERE IS NO PLT ERROR INVOLVED ASIDE FROM HAVING A RESPONSE TIME THAT EXCEEDS ZERO.

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.