EXCEEDED LIMIT OF HOLDING AIRSPACE.

Narrative

DUE TO WX AT DEST WE HAD A 45 MIN GND HOLD AFTER DEP FROM GATE. AFTER TKOF AND STILL WITH DEP CTL; WE WERE GIVEN HOLDING AT DITCH INTXN. WE HAD JUST ENOUGH TIME TO PROGRAM THE FMC AND FIGURE OUT WHAT HOLDING ENTRY WAS CALLED FOR; TO BE ABLE TO PROPERLY MONITOR PROGRESS; BEFORE WE GOT TO THE FIX. ABOUT 1 MIN AFTER CALLING ENTERING HOLD; WITH ACFT IN SHALLOW TURN TO OUTBOUND COURSE; ATC GAVE US AN IMMEDIATE TURN TO 280 DEGS OR APPROX A 180 DEG TURN AND SAID WE WERE BEYOND THE HOLDING AIRSPACE. WE THEN FOUND BY BELATEDLY LOOKING AT RAW DATA DME THAT THE FMC FIX POS WAS IN ERROR BY 6 MI. BY THE TIME WE MADE 1 LOOP OF THE PATTERN; THE FMC HAD UPDATED AND CORRECTED ITS POS. THIS INCIDENT COULD HAVE BEEN AVOIDED BY VERIFYING POS USING RAW DATA IN A TIMELY MANNER. SEVERAL FACTORS CONTRIBUTED; THE LONG GND HOLD PROBABLY WAS RESPONSIBLE FOR THE FMC POS ERROR (NO STATIONS TO UPDATE FROM). THERE WAS LIGHT TO MODERATE TURB. SUPPLEMENTAL INFO FROM ACN 318131: WE WERE TOLD TO HOLD AS PUBLISHED AT A FIX THAT IS ON THE DEP BUT THE HOLDING PATTERN WAS NOT SHOWN ON THE DEP PLATE; IT WAS ON A LOW ALT CHART. CREW WORKLOAD WAS HIGH; AND NOTIFICATION OF HOLD TIME WAS SHORT.