Crossing restr not met. FMC malfunction and flight crew confusion.

Attributes
ACN	303650
Time
Date	199505
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : lax
State Reference	CA
Altitude	msl bound lower : 11800 msl bound upper : 24000
Environment
Flight Conditions	Mixed
Light	Night
Aircraft 1
Controlling Facilities	tower : mci
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
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 150 flight time total : 9500 flight time type : 150
ASRS Report	303650
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 20000 flight time type : 757
ASRS Report	303568
Events
Anomaly	altitude deviation : overshoot altitude deviation : crossing restriction not met non adherence : published procedure other anomaly other
Independent Detector	other controllera 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:

While we were to descend out of FL330 to FL240, we were cleared for the civet 1 STAR lax. Both of us verified all altitude restrs in the FMC, then I switched to radio #2 to get the ATIS and talk to lax operations for in-range information. However, the 'descend now' command executed by the captain in the FMC was not functioning properly and wouldn't descend. The captain was flying the aircraft, using the FMC, as well as talking on the radio to the controller. Somehow the FMC deleted 2 out of the 3 hard altitude restrs (civet and bremr). The arnes altitude restr remain the same 10000 ft. We had descended to 11800 ft 3 mi before civet (14000 ft) when the controller noted our incorrect altitude. It was extremely busy as approach requested many airspeed changes. While the captain was wrestling with the FMC not functioning properly, I was busy on radio #2 and I feel that I should have switched back to radio #1 to assist the captain. That way, maybe I would have caught the altitude deletions from the FMC.

Original NASA ASRS Text

Title: XING RESTR NOT MET. FMC MALFUNCTION AND FLC CONFUSION.

Narrative: WHILE WE WERE TO DSND OUT OF FL330 TO FL240, WE WERE CLRED FOR THE CIVET 1 STAR LAX. BOTH OF US VERIFIED ALL ALT RESTRS IN THE FMC, THEN I SWITCHED TO RADIO #2 TO GET THE ATIS AND TALK TO LAX OPS FOR IN-RANGE INFO. HOWEVER, THE 'DSND NOW' COMMAND EXECUTED BY THE CAPT IN THE FMC WAS NOT FUNCTIONING PROPERLY AND WOULDN'T DSND. THE CAPT WAS FLYING THE ACFT, USING THE FMC, AS WELL AS TALKING ON THE RADIO TO THE CTLR. SOMEHOW THE FMC DELETED 2 OUT OF THE 3 HARD ALT RESTRS (CIVET AND BREMR). THE ARNES ALT RESTR REMAIN THE SAME 10000 FT. WE HAD DSNDED TO 11800 FT 3 MI BEFORE CIVET (14000 FT) WHEN THE CTLR NOTED OUR INCORRECT ALT. IT WAS EXTREMELY BUSY AS APCH REQUESTED MANY AIRSPD CHANGES. WHILE THE CAPT WAS WRESTLING WITH THE FMC NOT FUNCTIONING PROPERLY, I WAS BUSY ON RADIO #2 AND I FEEL THAT I SHOULD HAVE SWITCHED BACK TO RADIO #1 TO ASSIST THE CAPT. THAT WAY, MAYBE I WOULD HAVE CAUGHT THE ALT DELETIONS FROM THE FMC.

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.