Narrative:

I experienced a map shift -- the likes I've never seen. Most of us have seen subtle shifts -- maybe 1/4 mi or so, but just after liftoff from runway in uio, I got the 'terrain, pull up, terrain pull up.' I was in terrain mode with the 10 mi range selected. We were, fortunately, in VMC on a cavu day. I knew we were safe from any terrain, but the indication was solid red. We continued to climb in normal fashion but the warning persisted. I finally disabled the warning by pressing the override switch on the forward panel. (Again we were in VFR conditions, the WX was as clear as could be.) I then selected the range selector to 20 and saw that uio airport, which was right behind us less than 3 mi, was depicted over 10 mi to our left (east). We flew the departure on nothing but raw data and, using every means possible, determined that a map shift occurred just after liftoff to the tune of 11 mi. We monitored carefully the situation, flying only raw data. At tco, several mins into the flight, we determined that about 10.2 mi of map shift was still there. Still flying raw data or '727 mode' by the time we got to panama -- using 3 vors, DME data, and FMC data -- we both determined that the map shift had corrected itself and the FMC was now indicating correctly. Just wanted to report this, reminding crews that map shifts still occur and this is a strong indication that they can be very severe.

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Original NASA ASRS Text

Title: A DEPARTING B757 RECEIVES A FALSE GPWS WARNING WHICH THE CREW DETERMINED TO BE LINKED TO THEIR VERY LARGE MAP SHIFT THAT OCCURRED ON DEP FROM SEQU, FO.

Narrative: I EXPERIENCED A MAP SHIFT -- THE LIKES I'VE NEVER SEEN. MOST OF US HAVE SEEN SUBTLE SHIFTS -- MAYBE 1/4 MI OR SO, BUT JUST AFTER LIFTOFF FROM RWY IN UIO, I GOT THE 'TERRAIN, PULL UP, TERRAIN PULL UP.' I WAS IN TERRAIN MODE WITH THE 10 MI RANGE SELECTED. WE WERE, FORTUNATELY, IN VMC ON A CAVU DAY. I KNEW WE WERE SAFE FROM ANY TERRAIN, BUT THE INDICATION WAS SOLID RED. WE CONTINUED TO CLB IN NORMAL FASHION BUT THE WARNING PERSISTED. I FINALLY DISABLED THE WARNING BY PRESSING THE OVERRIDE SWITCH ON THE FORWARD PANEL. (AGAIN WE WERE IN VFR CONDITIONS, THE WX WAS AS CLR AS COULD BE.) I THEN SELECTED THE RANGE SELECTOR TO 20 AND SAW THAT UIO ARPT, WHICH WAS RIGHT BEHIND US LESS THAN 3 MI, WAS DEPICTED OVER 10 MI TO OUR L (E). WE FLEW THE DEP ON NOTHING BUT RAW DATA AND, USING EVERY MEANS POSSIBLE, DETERMINED THAT A MAP SHIFT OCCURRED JUST AFTER LIFTOFF TO THE TUNE OF 11 MI. WE MONITORED CAREFULLY THE SIT, FLYING ONLY RAW DATA. AT TCO, SEVERAL MINS INTO THE FLT, WE DETERMINED THAT ABOUT 10.2 MI OF MAP SHIFT WAS STILL THERE. STILL FLYING RAW DATA OR '727 MODE' BY THE TIME WE GOT TO PANAMA -- USING 3 VORS, DME DATA, AND FMC DATA -- WE BOTH DETERMINED THAT THE MAP SHIFT HAD CORRECTED ITSELF AND THE FMC WAS NOW INDICATING CORRECTLY. JUST WANTED TO RPT THIS, REMINDING CREWS THAT MAP SHIFTS STILL OCCUR AND THIS IS A STRONG INDICATION THAT THEY CAN BE VERY SEVERE.

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.