Md-88 has FMS failure of heading system and map display. Overshoots ILS intercept.

Attributes
ACN	306957
Time
Date	199506
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : atl
State Reference	GA
Altitude	msl bound lower : 4000 msl bound upper : 4500
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : atl
Operator	common carrier : air carrier
Make Model Name	MD-88
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : cfi pilot : commercial pilot : instrument pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 6000 flight time type : 300
ASRS Report	306957
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance none taken : unable other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Flight msp-atl. Lost both captain and first officer heading system, and map display. Reduced to magnetic compass only, which on md-88 is completely worthless (mirror system). Requested no gyroscope vectors to visual approach. Controller asked if we could fly localizer course if he vectored us to it. We accepted. Cleared to fly the approach, maintaining 5000 ft till established. Assuming the last vector was close to approach course, initiated descent. Did not know that it was actually still a large intercept angle to final, overshot, and may have been a conflict with traffic on approach to atlanta runway 27L. Controller noted the overshoot and directed an immediate turn and climb to 4500 ft. In the process of complying, got the field in sight and traffic to runway 27L in sight, accepted visual approach and landed uneventfully. Problem causes: worthless standby compass system on md-88. Large intercept angle to final in hazy conditions. Suggest controller give an idea of intercept angle or clock position of airport on last vector.

Original NASA ASRS Text

Title: MD-88 HAS FMS FAILURE OF HDG SYS AND MAP DISPLAY. OVERSHOOTS ILS INTERCEPT.

Narrative: FLT MSP-ATL. LOST BOTH CAPT AND FO HDG SYS, AND MAP DISPLAY. REDUCED TO MAGNETIC COMPASS ONLY, WHICH ON MD-88 IS COMPLETELY WORTHLESS (MIRROR SYS). REQUESTED NO GYROSCOPE VECTORS TO VISUAL APCH. CTLR ASKED IF WE COULD FLY LOC COURSE IF HE VECTORED US TO IT. WE ACCEPTED. CLRED TO FLY THE APCH, MAINTAINING 5000 FT TILL ESTABLISHED. ASSUMING THE LAST VECTOR WAS CLOSE TO APCH COURSE, INITIATED DSCNT. DID NOT KNOW THAT IT WAS ACTUALLY STILL A LARGE INTERCEPT ANGLE TO FINAL, OVERSHOT, AND MAY HAVE BEEN A CONFLICT WITH TFC ON APCH TO ATLANTA RWY 27L. CTLR NOTED THE OVERSHOOT AND DIRECTED AN IMMEDIATE TURN AND CLB TO 4500 FT. IN THE PROCESS OF COMPLYING, GOT THE FIELD IN SIGHT AND TFC TO RWY 27L IN SIGHT, ACCEPTED VISUAL APCH AND LANDED UNEVENTFULLY. PROB CAUSES: WORTHLESS STANDBY COMPASS SYS ON MD-88. LARGE INTERCEPT ANGLE TO FINAL IN HAZY CONDITIONS. SUGGEST CTLR GIVE AN IDEA OF INTERCEPT ANGLE OR CLOCK POS OF ARPT ON LAST VECTOR.

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.