B757 crew had FMC map shift on arrival at msp.

Attributes
ACN	483029
Time
Date	200008
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : msp.airport
State Reference	MN
Altitude	msl single value : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : m98.tracon
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 30 other
Flight Phase	descent : approach
Route In Use	approach : visual arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 13500 flight time type : 2000
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe inflight encounter other other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : anomaly accepted
Supplementary
Problem Areas	Aircraft Navigational Facility
Primary Problem	Navigational Facility
Situations
Navigational Aid	MSP.VORTAC

Narrative:

While being vectored for visual approach to runway 30 at kmsp, we experienced a map shift on the navigation display generated by the FMC. We were on the center line of the localizer (raw data) with a cross track error of 1.1 NM with reference to the center line of the localizer as determined by the FMC. There is an ongoing problem with a NAVAID or navaids in the kmsp terminal area as my company had put out a bulletin about possible map shifts occurring in the area. Inaccurate DME information from the NAVAID(south) is causing an inaccurate FMC display of position. Callback conversation with reporter revealed the following information: the company has issued a bulletin to flight crews to deselect msp in the FMC database. Reporter did not know what was updating the FMC. At this point in the approach, workload prevents a crew member being tied up in FMC operation. Reporter has flown other approachs to msp with the msp VORTAC deselected, and has not experienced the map shift.

Original NASA ASRS Text

Title: B757 CREW HAD FMC MAP SHIFT ON ARRIVAL AT MSP.

Narrative: WHILE BEING VECTORED FOR VISUAL APCH TO RWY 30 AT KMSP, WE EXPERIENCED A MAP SHIFT ON THE NAV DISPLAY GENERATED BY THE FMC. WE WERE ON THE CENTER LINE OF THE LOCALIZER (RAW DATA) WITH A CROSS TRACK ERROR OF 1.1 NM WITH REFERENCE TO THE CENTER LINE OF THE LOCALIZER AS DETERMINED BY THE FMC. THERE IS AN ONGOING PROBLEM WITH A NAVAID OR NAVAIDS IN THE KMSP TERMINAL AREA AS MY COMPANY HAD PUT OUT A BULLETIN ABOUT POSSIBLE MAP SHIFTS OCCURRING IN THE AREA. INACCURATE DME INFORMATION FROM THE NAVAID(S) IS CAUSING AN INACCURATE FMC DISPLAY OF POSITION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE COMPANY HAS ISSUED A BULLETIN TO FLT CREWS TO DESELECT MSP IN THE FMC DATABASE. RPTR DID NOT KNOW WHAT WAS UPDATING THE FMC. AT THIS POINT IN THE APCH, WORKLOAD PREVENTS A CREW MEMBER BEING TIED UP IN FMC OPERATION. RPTR HAS FLOWN OTHER APCHS TO MSP WITH THE MSP VORTAC DESELECTED, AND HAS NOT EXPERIENCED THE MAP SHIFT.

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.