Narrative:

The first officer was flying this leg. Initially we were cleared to cross kubbs intersection at 10000'. First officer was inserting data into the performance management system to let the aircraft do it. Pms takes a long time to think things through. I was expecting kubbs at 10000' because other flts on the frequency had been assigned it. I knew it was tight because I was thinking about it before we received clearance. I announced to the first officer the miles to the crossing point and the number of thousand ft we had to lose. He then went to vertical speed mode, closed the throttles and fully extended speed brakes. The controller then gave us descent to 11000', I think to help us because he didn't think we could make it. Later it became obvious we could make it and the controller gave us kubbs at 10000' and 250 KTS. The medium large transport was still descending quite rapidly. Because of the high sink rate and close crossing restriction, I was watching my flight instruments quite closely. My flight mode annunciator was showing altitude capture as being armed until we approached 10000'. At that point it dropped off. We went through 10000' at a fairly high rate of sink. At 9900' I pulled back on the yoke, the first officer rearmed the altitude present. The airplane continued to descend. I disengaged the autoplt and stopped the descent at 9800' with an abrupt jerk back on the yoke. I got the airplane back to 10000', trimmed and at the correct speed, looked up and saw 11000' in the altitude preselect window. Since the first officer had been flying with the autoplt on, he had been resetting the altitudes. I got everything set up, re-engaged the autoplt and gave the airplane back to the first officer. Apparently he was pretty shook because when we descended below 10000' he allowed the airspeed to build above 250 KTS. I had to tell him to slow to 250 KTS. The altitude preselect window is far away from viewing range especially from the left seat. It would be nice to have an altitude preselect repeater in the flight mode annunciator or somewhere close to the flight instruments. Also, it seems difficult sometimes to know how far to let the automatic equipment go or when to step in and take command of the situation. Supplemental information from acn 86802: pitch down of aircraft was due to excessive nose down trim from autoplt. The excessive nose down trim surprised both of us and it took 200' to recover.

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Original NASA ASRS Text

Title: DURING DESCENT, MLG OVERSHOT ASSIGNED ALT BY 200'.

Narrative: THE F/O WAS FLYING THIS LEG. INITIALLY WE WERE CLRED TO CROSS KUBBS INTXN AT 10000'. F/O WAS INSERTING DATA INTO THE PERFORMANCE MGMNT SYS TO LET THE ACFT DO IT. PMS TAKES A LONG TIME TO THINK THINGS THROUGH. I WAS EXPECTING KUBBS AT 10000' BECAUSE OTHER FLTS ON THE FREQ HAD BEEN ASSIGNED IT. I KNEW IT WAS TIGHT BECAUSE I WAS THINKING ABOUT IT BEFORE WE RECEIVED CLRNC. I ANNOUNCED TO THE F/O THE MILES TO THE XING POINT AND THE NUMBER OF THOUSAND FT WE HAD TO LOSE. HE THEN WENT TO VERTICAL SPEED MODE, CLOSED THE THROTTLES AND FULLY EXTENDED SPD BRAKES. THE CTLR THEN GAVE US DSCNT TO 11000', I THINK TO HELP US BECAUSE HE DIDN'T THINK WE COULD MAKE IT. LATER IT BECAME OBVIOUS WE COULD MAKE IT AND THE CTLR GAVE US KUBBS AT 10000' AND 250 KTS. THE MLG WAS STILL DSNDING QUITE RAPIDLY. BECAUSE OF THE HIGH SINK RATE AND CLOSE XING RESTRICTION, I WAS WATCHING MY FLT INSTRUMENTS QUITE CLOSELY. MY FLT MODE ANNUNCIATOR WAS SHOWING ALT CAPTURE AS BEING ARMED UNTIL WE APCHED 10000'. AT THAT POINT IT DROPPED OFF. WE WENT THROUGH 10000' AT A FAIRLY HIGH RATE OF SINK. AT 9900' I PULLED BACK ON THE YOKE, THE F/O REARMED THE ALT PRESENT. THE AIRPLANE CONTINUED TO DSND. I DISENGAGED THE AUTOPLT AND STOPPED THE DSCNT AT 9800' WITH AN ABRUPT JERK BACK ON THE YOKE. I GOT THE AIRPLANE BACK TO 10000', TRIMMED AND AT THE CORRECT SPD, LOOKED UP AND SAW 11000' IN THE ALT PRESELECT WINDOW. SINCE THE F/O HAD BEEN FLYING WITH THE AUTOPLT ON, HE HAD BEEN RESETTING THE ALTS. I GOT EVERYTHING SET UP, RE-ENGAGED THE AUTOPLT AND GAVE THE AIRPLANE BACK TO THE F/O. APPARENTLY HE WAS PRETTY SHOOK BECAUSE WHEN WE DSNDED BELOW 10000' HE ALLOWED THE AIRSPD TO BUILD ABOVE 250 KTS. I HAD TO TELL HIM TO SLOW TO 250 KTS. THE ALT PRESELECT WINDOW IS FAR AWAY FROM VIEWING RANGE ESPECIALLY FROM THE LEFT SEAT. IT WOULD BE NICE TO HAVE AN ALT PRESELECT REPEATER IN THE FLT MODE ANNUNCIATOR OR SOMEWHERE CLOSE TO THE FLT INSTRUMENTS. ALSO, IT SEEMS DIFFICULT SOMETIMES TO KNOW HOW FAR TO LET THE AUTOMATIC EQUIP GO OR WHEN TO STEP IN AND TAKE COMMAND OF THE SITUATION. SUPPLEMENTAL INFO FROM ACN 86802: PITCH DOWN OF ACFT WAS DUE TO EXCESSIVE NOSE DOWN TRIM FROM AUTOPLT. THE EXCESSIVE NOSE DOWN TRIM SURPRISED BOTH OF US AND IT TOOK 200' TO RECOVER.

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.