Narrative:

We were proceeding direct to knox (oxi) VOR/DME using RNAV. We were cruising at FL250 and had just been told to descend to 14000 ft MSL. Since the RNAV can only be coupled to the #1 autoplt, and I wanted to use my own #2 autoplt (in order to couple it to my own #2 VOR), I disengaged the #1 autoplt and engaged the #2 autoplt. When you switch from one autoplt to the other, you must re-engage both the autoplt and autothrottles. When I tried to re- engage the autothrottle and #2 autoplt, I didn't notice that the #2 autoplt did not engage. I focused my attention on the flight director panel and programmed a 2000 FPM descent, not noticing that the vsi and altimeter were showing a climb. My first clue that something was wrong came when the autothrottles advanced power. Initially, I believed there was an autothrottle malfunction since the throttles should have retarded for the descent. In reality, since the #2 autoplt was not engaged, it allowed the aircraft to start a climb. The climb caused the airspeed to bleed off, and the autothrottles properly advanced, which caused the airplane to climb even more rapidly. At about FL255, I disengaged both the autothrottles and autoplt (not realizing the autoplt was not engaged). We reached about FL256 before I could establish the descent. I then told the captain that I believed we had an autothrottle and autoplt malfunction. For a while, he didn't say much. I continued to puzzle at how this failure of autothrottle and autoplt could occur. At one point, I said, 'I wish I knew what had happened.' he then said that he could tell me what happened. I invited him to explain. He went on to list the events in detail. I was dumbfounded to learn he allowed this chain of events to continue. I asked him why he didn't do or say anything about the situation. He said he told me once that we were 200 ft high. I told him that I didn't hear his alert and wondered why he didn't do or say anything more. He responded by saying that he didn't want to upset me by appearing to 'direct' me as I had complained of 2 days earlier. 2 days earlier the captain directed me on when to descend, turn and reduce airspeed on a visual approach into la guardia, ny. I told him then that I felt he was too directive in a situation where pilot technique was involved, and no conflict was imminent.

Related reports:

Google
 

Original NASA ASRS Text

Title: FO, UNAWARE HE FAILED TO FULLY ENGAGE THE AUTOPLT, IS UNAWARE THAT THE ACFT IS CLBING ABOVE ASSIGNED ALT.

Narrative: WE WERE PROCEEDING DIRECT TO KNOX (OXI) VOR/DME USING RNAV. WE WERE CRUISING AT FL250 AND HAD JUST BEEN TOLD TO DSND TO 14000 FT MSL. SINCE THE RNAV CAN ONLY BE COUPLED TO THE #1 AUTOPLT, AND I WANTED TO USE MY OWN #2 AUTOPLT (IN ORDER TO COUPLE IT TO MY OWN #2 VOR), I DISENGAGED THE #1 AUTOPLT AND ENGAGED THE #2 AUTOPLT. WHEN YOU SWITCH FROM ONE AUTOPLT TO THE OTHER, YOU MUST RE-ENGAGE BOTH THE AUTOPLT AND AUTOTHROTTLES. WHEN I TRIED TO RE- ENGAGE THE AUTOTHROTTLE AND #2 AUTOPLT, I DIDN'T NOTICE THAT THE #2 AUTOPLT DID NOT ENGAGE. I FOCUSED MY ATTN ON THE FLT DIRECTOR PANEL AND PROGRAMMED A 2000 FPM DSCNT, NOT NOTICING THAT THE VSI AND ALTIMETER WERE SHOWING A CLB. MY FIRST CLUE THAT SOMETHING WAS WRONG CAME WHEN THE AUTOTHROTTLES ADVANCED PWR. INITIALLY, I BELIEVED THERE WAS AN AUTOTHROTTLE MALFUNCTION SINCE THE THROTTLES SHOULD HAVE RETARDED FOR THE DSCNT. IN REALITY, SINCE THE #2 AUTOPLT WAS NOT ENGAGED, IT ALLOWED THE ACFT TO START A CLB. THE CLB CAUSED THE AIRSPD TO BLEED OFF, AND THE AUTOTHROTTLES PROPERLY ADVANCED, WHICH CAUSED THE AIRPLANE TO CLB EVEN MORE RAPIDLY. AT ABOUT FL255, I DISENGAGED BOTH THE AUTOTHROTTLES AND AUTOPLT (NOT REALIZING THE AUTOPLT WAS NOT ENGAGED). WE REACHED ABOUT FL256 BEFORE I COULD ESTABLISH THE DSCNT. I THEN TOLD THE CAPT THAT I BELIEVED WE HAD AN AUTOTHROTTLE AND AUTOPLT MALFUNCTION. FOR A WHILE, HE DIDN'T SAY MUCH. I CONTINUED TO PUZZLE AT HOW THIS FAILURE OF AUTOTHROTTLE AND AUTOPLT COULD OCCUR. AT ONE POINT, I SAID, 'I WISH I KNEW WHAT HAD HAPPENED.' HE THEN SAID THAT HE COULD TELL ME WHAT HAPPENED. I INVITED HIM TO EXPLAIN. HE WENT ON TO LIST THE EVENTS IN DETAIL. I WAS DUMBFOUNDED TO LEARN HE ALLOWED THIS CHAIN OF EVENTS TO CONTINUE. I ASKED HIM WHY HE DIDN'T DO OR SAY ANYTHING ABOUT THE SIT. HE SAID HE TOLD ME ONCE THAT WE WERE 200 FT HIGH. I TOLD HIM THAT I DIDN'T HEAR HIS ALERT AND WONDERED WHY HE DIDN'T DO OR SAY ANYTHING MORE. HE RESPONDED BY SAYING THAT HE DIDN'T WANT TO UPSET ME BY APPEARING TO 'DIRECT' ME AS I HAD COMPLAINED OF 2 DAYS EARLIER. 2 DAYS EARLIER THE CAPT DIRECTED ME ON WHEN TO DSND, TURN AND REDUCE AIRSPD ON A VISUAL APCH INTO LA GUARDIA, NY. I TOLD HIM THEN THAT I FELT HE WAS TOO DIRECTIVE IN A SIT WHERE PLT TECHNIQUE WAS INVOLVED, AND NO CONFLICT WAS IMMINENT.

Data retrieved from NASA's ASRS site as of July 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.