Altitude deviation. Altitude overshot in climb.

Attributes
ACN	116429
Time
Date	198907
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ptw airport : phl
State Reference	PA
Altitude	msl bound lower : 10000 msl bound upper : 10500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : phl
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Route In Use	departure other enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 130 flight time total : 3500 flight time type : 200
ASRS Report	116429
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 184 flight time total : 13602 flight time type : 906
ASRS Report	116232
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On climbout we were cleared to 10,000', and at approximately 8000' we were cleared direct to pottstown VOR. The captain was entering the data into the FMC, and I was hand flying the aircraft. Both of us were watching outside as well. Both flight directors (F/D) were on. The rate of climb was between 3500 and 4000 FPM. When I checked my F/D it was still commanding a climb and the altimeter read approximately 10,000'. I started the level off immediately, and the highest altitude we achieved was 10,500'. Once I got the aircraft back to 10,000 I compared the two F/D's and the captain's showed straight and level, while my F/D showed a climb of about 150 up. I turned off my F/D and then back on and it showed straight and level. On the following 2 intermediate level offs, my F/D did the same thing. It directed a climb while the captain's F/D showed straight and level. We noted that the mode control panel showed altitude hold and a climb in vertical speed at the same time (this is not supposed to be able to happen). The level off at cruise altitude was normal, and the rest of the flight was uneventful. We wrote up the problem in the maintenance logbook. I believe the F/D malfunction was the main cause of this event.

Original NASA ASRS Text

Title: ALT DEVIATION. ALT OVERSHOT IN CLIMB.

Narrative: ON CLIMBOUT WE WERE CLRED TO 10,000', AND AT APPROX 8000' WE WERE CLRED DIRECT TO POTTSTOWN VOR. THE CAPT WAS ENTERING THE DATA INTO THE FMC, AND I WAS HAND FLYING THE ACFT. BOTH OF US WERE WATCHING OUTSIDE AS WELL. BOTH FLT DIRECTORS (F/D) WERE ON. THE RATE OF CLIMB WAS BETWEEN 3500 AND 4000 FPM. WHEN I CHECKED MY F/D IT WAS STILL COMMANDING A CLIMB AND THE ALTIMETER READ APPROX 10,000'. I STARTED THE LEVEL OFF IMMEDIATELY, AND THE HIGHEST ALT WE ACHIEVED WAS 10,500'. ONCE I GOT THE ACFT BACK TO 10,000 I COMPARED THE TWO F/D'S AND THE CAPT'S SHOWED STRAIGHT AND LEVEL, WHILE MY F/D SHOWED A CLIMB OF ABOUT 150 UP. I TURNED OFF MY F/D AND THEN BACK ON AND IT SHOWED STRAIGHT AND LEVEL. ON THE FOLLOWING 2 INTERMEDIATE LEVEL OFFS, MY F/D DID THE SAME THING. IT DIRECTED A CLIMB WHILE THE CAPT'S F/D SHOWED STRAIGHT AND LEVEL. WE NOTED THAT THE MODE CONTROL PANEL SHOWED ALT HOLD AND A CLIMB IN VERTICAL SPEED AT THE SAME TIME (THIS IS NOT SUPPOSED TO BE ABLE TO HAPPEN). THE LEVEL OFF AT CRUISE ALT WAS NORMAL, AND THE REST OF THE FLT WAS UNEVENTFUL. WE WROTE UP THE PROBLEM IN THE MAINT LOGBOOK. I BELIEVE THE F/D MALFUNCTION WAS THE MAIN CAUSE OF THIS EVENT.

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.