When FMC fails, B737-400 loses all heading information except the wet compass.

Attributes
ACN	350063
Time
Date	199610
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : psp
State Reference	CA
Altitude	msl bound lower : 33000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla
Operator	common carrier : air carrier
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 2000
ASRS Report	350063
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Cruise altitude, about to descend, the autoplt disconnects, FMC fails and we lose all compass information. Our only heading information is the wet compass. We remain VFR and land at nearest suitable airport, psp. The problem went routinely. The problem is a 2 pilot jet aircraft in a busy ATC environment with a problem. In my opinion, as long as all in going well, 2 pilot crews are ok. When there is a problem, 2 pilots in a cockpit, the workload goes off scale, which makes room for potential mistakes. I would much rather fly an aircraft in today's busy ATC and work environment with a flight engineer, than in a 2 pilot jet. I believe that we have compromised safety in going to 2 pilot jet aircraft under the real reason of saving money.

Original NASA ASRS Text

Title: WHEN FMC FAILS, B737-400 LOSES ALL HDG INFO EXCEPT THE WET COMPASS.

Narrative: CRUISE ALT, ABOUT TO DSND, THE AUTOPLT DISCONNECTS, FMC FAILS AND WE LOSE ALL COMPASS INFO. OUR ONLY HDG INFO IS THE WET COMPASS. WE REMAIN VFR AND LAND AT NEAREST SUITABLE ARPT, PSP. THE PROB WENT ROUTINELY. THE PROB IS A 2 PLT JET ACFT IN A BUSY ATC ENVIRONMENT WITH A PROB. IN MY OPINION, AS LONG AS ALL IN GOING WELL, 2 PLT CREWS ARE OK. WHEN THERE IS A PROB, 2 PLTS IN A COCKPIT, THE WORKLOAD GOES OFF SCALE, WHICH MAKES ROOM FOR POTENTIAL MISTAKES. I WOULD MUCH RATHER FLY AN ACFT IN TODAY'S BUSY ATC AND WORK ENVIRONMENT WITH A FE, THAN IN A 2 PLT JET. I BELIEVE THAT WE HAVE COMPROMISED SAFETY IN GOING TO 2 PLT JET ACFT UNDER THE REAL REASON OF SAVING MONEY.

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.