FMS failed to make programmed turn at harrp intersection.

Attributes
ACN	210056
Time
Date	199205
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : lga
State Reference	NY
Altitude	msl bound lower : 4000 msl bound upper : 4000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival star : star
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : atp
Experience	flight time total : 17500 flight time type : 400
ASRS Report	210056
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

Due to heavy WX on normal arrival route (nanci arrival) we were re- rted to the extol arrival to avoid the WX. During descent, approaching the harrp intersection, I experienced FMC failure. In a few seconds, the FMC came back on and shortly thereafter, the flight director (on my side also) failed. -- I was trying to locate the proper circuit breakers to reset the flight director when it suddenly came back on. The aircraft had failed to make the turn at harrp to lga and both the first officer and I failed to notice due to the distraction. Approach control pointed this out to us and then gave us a vector. These type of electrical glitches seem quite common on the medium large transport, although I am new on the type I've already seen several. Callback conversation with reporter revealed the following information: reporter now as 400 hours on aircraft. He said the 'nervous system on the aircraft is lousy.' a common problem: the FMC is programmed to cross a point at and intercept an altitude. It makes the crossing restriction but fails to capture the altitude. Often, when a route is re-entered or amended, the FMC seems to be overloaded and is lost. He added that the navigation control system is written up about once per leg on average.

Original NASA ASRS Text

Title: FMS FAILED TO MAKE PROGRAMMED TURN AT HARRP INTXN.

Narrative: DUE TO HVY WX ON NORMAL ARR RTE (NANCI ARR) WE WERE RE- RTED TO THE EXTOL ARR TO AVOID THE WX. DURING DSCNT, APCHING THE HARRP INTXN, I EXPERIENCED FMC FAILURE. IN A FEW SECONDS, THE FMC CAME BACK ON AND SHORTLY THEREAFTER, THE FLT DIRECTOR (ON MY SIDE ALSO) FAILED. -- I WAS TRYING TO LOCATE THE PROPER CIRCUIT BREAKERS TO RESET THE FLT DIRECTOR WHEN IT SUDDENLY CAME BACK ON. THE ACFT HAD FAILED TO MAKE THE TURN AT HARRP TO LGA AND BOTH THE FO AND I FAILED TO NOTICE DUE TO THE DISTR. APCH CTL POINTED THIS OUT TO US AND THEN GAVE US A VECTOR. THESE TYPE OF ELECTRICAL GLITCHES SEEM QUITE COMMON ON THE MLG, ALTHOUGH I AM NEW ON THE TYPE I'VE ALREADY SEEN SEVERAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR NOW AS 400 HRS ON ACFT. HE SAID THE 'NERVOUS SYS ON THE ACFT IS LOUSY.' A COMMON PROBLEM: THE FMC IS PROGRAMMED TO CROSS A POINT AT AND INTERCEPT AN ALT. IT MAKES THE XING RESTRICTION BUT FAILS TO CAPTURE THE ALT. OFTEN, WHEN A RTE IS RE-ENTERED OR AMENDED, THE FMC SEEMS TO BE OVERLOADED AND IS LOST. HE ADDED THAT THE NAV CTL SYS IS WRITTEN UP ABOUT ONCE PER LEG ON AVERAGE.

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.