Corp medium large transport fails to thoroughly check ground position on INS. Must return land.

Attributes
ACN	277227
Time
Date	199407
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : anc
State Reference	AK
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : anc
Operator	general aviation : corporate
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 91
Navigation In Use	Other Other
Flight Phase	climbout : takeoff landing other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 13000 flight time type : 100
ASRS Report	277227
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Departing panc for RJ55. Prior to departure, loaded ramp coordinates into INS. Double-checked data and then X filed into #2 INS per company SOP. This was a quick turn/crew changes-inbound crew had no negative comments about aircraft. I did not check for inbound errors in INS position. Received ATC clearance. Both pilots loaded flight plan into FMS and crosschecked to ensure the INS position update had 'taken' (dong so was not part of our SOP -- just the flight plan). After takeoff and leaving 11000 ft, ATC cleared us direct to a fix. I selected the fix on my INS/FMS -- something didn't look right. Investigation showed that both INS's were off by 57 NM (.95 long plus a wee bit off laterally). Can't update INS in flight in this installation -- no choice but return to panc and update on ground. Made overweight landing. Moral: we are changing SOP to have both pilots verify ramp position -- xchking ramp the same as the flight plan. Other factors (no excuses) inbound crew had had trouble with the FMS computed position, due to VLF input, and didn't inform us (outbound crew).

Original NASA ASRS Text

Title: CORP MLG FAILS TO THOROUGHLY CHK GND POS ON INS. MUST RETURN LAND.

Narrative: DEPARTING PANC FOR RJ55. PRIOR TO DEP, LOADED RAMP COORDINATES INTO INS. DOUBLE-CHKED DATA AND THEN X FILED INTO #2 INS PER COMPANY SOP. THIS WAS A QUICK TURN/CREW CHANGES-INBOUND CREW HAD NO NEGATIVE COMMENTS ABOUT ACFT. I DID NOT CHK FOR INBOUND ERRORS IN INS POS. RECEIVED ATC CLRNC. BOTH PLTS LOADED FLT PLAN INTO FMS AND XCHKED TO ENSURE THE INS POS UPDATE HAD 'TAKEN' (DONG SO WAS NOT PART OF OUR SOP -- JUST THE FLT PLAN). AFTER TKOF AND LEAVING 11000 FT, ATC CLRED US DIRECT TO A FIX. I SELECTED THE FIX ON MY INS/FMS -- SOMETHING DIDN'T LOOK RIGHT. INVESTIGATION SHOWED THAT BOTH INS'S WERE OFF BY 57 NM (.95 LONG PLUS A WEE BIT OFF LATERALLY). CAN'T UPDATE INS IN FLT IN THIS INSTALLATION -- NO CHOICE BUT RETURN TO PANC AND UPDATE ON GND. MADE OVERWT LNDG. MORAL: WE ARE CHANGING SOP TO HAVE BOTH PLTS VERIFY RAMP POS -- XCHKING RAMP THE SAME AS THE FLT PLAN. OTHER FACTORS (NO EXCUSES) INBOUND CREW HAD HAD TROUBLE WITH THE FMS COMPUTED POS, DUE TO VLF INPUT, AND DIDN'T INFORM US (OUTBOUND CREW).

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.