Flight crew of an medium large transport overshot assigned descent altitude due to the aircraft FMC ...

Attributes
ACN	308350
Time
Date	199506
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : dfw
State Reference	TX
Altitude	msl bound lower : 10800 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other arrival star : star enroute airway : dfw
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 166 flight time total : 14700 flight time type : 2400
ASRS Report	308350
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

We were descending into dfw, using the autoplt, LNAV, and VNAV, to cross the fix at 11000 ft 250 KTS. 11000 ft was set in the altitude window on the mode control panel and the fix was properly programmed in the FMS. All functions had been working on 2 previous legs. The deviation indicator shown that we could be about 1 mi long in the descent but the aircraft was slowing to 250 KTS and when slowed started a descent to arrive at the fix on speed and at 11000 ft. At the fix the aircraft did not level but continued a 1000 FPM descent. I disengaged the autoplt and leveled at 10800 ft. We climbed back to 11000 ft and continued the approach without the FMS. There was no observed traffic at the time. The mode control panel, altimeters and FMS were rechked and were set properly.

Original NASA ASRS Text

Title: FLC OF AN MLG OVERSHOT ASSIGNED DSCNT ALT DUE TO THE ACFT FMC PROB.

Narrative: WE WERE DSNDING INTO DFW, USING THE AUTOPLT, LNAV, AND VNAV, TO CROSS THE FIX AT 11000 FT 250 KTS. 11000 FT WAS SET IN THE ALT WINDOW ON THE MODE CTL PANEL AND THE FIX WAS PROPERLY PROGRAMMED IN THE FMS. ALL FUNCTIONS HAD BEEN WORKING ON 2 PREVIOUS LEGS. THE DEV INDICATOR SHOWN THAT WE COULD BE ABOUT 1 MI LONG IN THE DSCNT BUT THE ACFT WAS SLOWING TO 250 KTS AND WHEN SLOWED STARTED A DSCNT TO ARRIVE AT THE FIX ON SPD AND AT 11000 FT. AT THE FIX THE ACFT DID NOT LEVEL BUT CONTINUED A 1000 FPM DSCNT. I DISENGAGED THE AUTOPLT AND LEVELED AT 10800 FT. WE CLBED BACK TO 11000 FT AND CONTINUED THE APCH WITHOUT THE FMS. THERE WAS NO OBSERVED TFC AT THE TIME. THE MODE CTL PANEL, ALTIMETERS AND FMS WERE RECHKED AND WERE SET PROPERLY.

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.

Flight crew of an medium large transport overshot assigned descent altitude due to the aircraft FMC problem.