Narrative:

After our 3 hour productivity break, we were ready to fly a flight back to dfw. Our flight was planned over water, but the implications of the fact that the GPS was placarded inoperative did not sink in to me. The inbound captain had written an information to maintenance stating that they had monitored the GPS inbound to fll and it seemed to be accurate and working fine. I was thinking we will do the same on the way back. On taxi out, my first officer remarked that he thought we were not legal going over water with the GPS placarded. After checking that the distances were indeed too great for VOR navigation (ADF's aren't there any more), we attempted to contact dispatch. After being unsuccessful in those attempts, we took off planning to refile overland once airborne. We had extra fuel for WX avoidance and were planned to arrive with 14000 pounds of gas, alternates of okc and dal, so I felt we were safe and legal to go. After airborne, we contacted dispatch and agreed on the overland route which was flown without incident. In hindsight, I may not have been legal for takeoff with the flight plan I had since I was planning to fly a different route and had not updated the alternates and the fuel required. The dispatcher and I had both overlooked the implications of the placarded GPS. Thanks to an excellent first officer who caught it, nothing happened, but I will be more alert the next time.

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Original NASA ASRS Text

Title: AN MD80 CAPT RPTED THAT HE DEPARTED FLL FOR AN OVER WATER FLT, EVEN THOUGH HIS FO POINTED OUT THAT THE GPS WAS PLACARDED INOP.

Narrative: AFTER OUR 3 HR PRODUCTIVITY BREAK, WE WERE READY TO FLY A FLT BACK TO DFW. OUR FLT WAS PLANNED OVER WATER, BUT THE IMPLICATIONS OF THE FACT THAT THE GPS WAS PLACARDED INOP DID NOT SINK IN TO ME. THE INBOUND CAPT HAD WRITTEN AN INFO TO MAINT STATING THAT THEY HAD MONITORED THE GPS INBOUND TO FLL AND IT SEEMED TO BE ACCURATE AND WORKING FINE. I WAS THINKING WE WILL DO THE SAME ON THE WAY BACK. ON TAXI OUT, MY FO REMARKED THAT HE THOUGHT WE WERE NOT LEGAL GOING OVER WATER WITH THE GPS PLACARDED. AFTER CHKING THAT THE DISTANCES WERE INDEED TOO GREAT FOR VOR NAV (ADF'S AREN'T THERE ANY MORE), WE ATTEMPTED TO CONTACT DISPATCH. AFTER BEING UNSUCCESSFUL IN THOSE ATTEMPTS, WE TOOK OFF PLANNING TO REFILE OVERLAND ONCE AIRBORNE. WE HAD EXTRA FUEL FOR WX AVOIDANCE AND WERE PLANNED TO ARRIVE WITH 14000 LBS OF GAS, ALTERNATES OF OKC AND DAL, SO I FELT WE WERE SAFE AND LEGAL TO GO. AFTER AIRBORNE, WE CONTACTED DISPATCH AND AGREED ON THE OVERLAND RTE WHICH WAS FLOWN WITHOUT INCIDENT. IN HINDSIGHT, I MAY NOT HAVE BEEN LEGAL FOR TKOF WITH THE FLT PLAN I HAD SINCE I WAS PLANNING TO FLY A DIFFERENT RTE AND HAD NOT UPDATED THE ALTERNATES AND THE FUEL REQUIRED. THE DISPATCHER AND I HAD BOTH OVERLOOKED THE IMPLICATIONS OF THE PLACARDED GPS. THANKS TO AN EXCELLENT FO WHO CAUGHT IT, NOTHING HAPPENED, BUT I WILL BE MORE ALERT THE NEXT TIME.

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.