Narrative:

On arrival at our aircraft we found out that the right GPS was placarded inoperative. As per MEL; we could fly with one GPS inoperative. We also had map display failures on both pilot displays. Numerous calls were made to maintenance control; dispatch and maintenance to find out if the map malfunction was a result of the GPS being placarded inoperative. There was never a consensus on why there was a map display malfunction. Without maintenance ever arriving at the aircraft the map function on both displays started working. Again we called dispatch and maintenance and concluded that we were good to takeoff. On takeoff both flight directors disappeared. We turned the flight director switches off and then on and were able to regain our flight directors. The first officer was unable to engage the autopilot on either side and was having to hand-fly the aircraft. Passing thru 15;000 ft; we noticed a smell in the cockpit like something was burning. At the same time the flight attendants called up that they smelled something like it was burning. (They had not turned on the ovens or the coffee makers when we got the smell). Not knowing where the smell was coming from we decided to declare an emergency and return to the airport. We accomplished the 'smoke; fire or fumes' QRH checklist. The flight attendants turned off the power ports and wifi and immediately searched the cabin to look for what might be causing the smell. The smell subsided as rapidly as it came without any indication of where it came from. During the return to the airport the first officer was getting what we determined to be unreliable inputs from the flight directors. Because of declaring an emergency we requested that arff trucks meet us on landing and check us over before taxiing. The landing was an uneventful normal landing. Excellent job by all crewmembers and should be commended for their expertise and job well done. Crew coordination between the cabin crew and flight crew was outstanding.

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Original NASA ASRS Text

Title: A B737-800 with the right GPS inoperative during preflight then had both MAP displays indicate failed. Unable to get maintenance and after the MAPs returned to normal; the flight departed only to declare an emergency and return to land because of an electrical burning smell.

Narrative: On arrival at our aircraft we found out that the right GPS was placarded inoperative. As per MEL; we could fly with one GPS inoperative. We also had MAP display failures on both pilot displays. Numerous calls were made to Maintenance Control; Dispatch and Maintenance to find out if the MAP malfunction was a result of the GPS being placarded inoperative. There was never a consensus on why there was a MAP display malfunction. Without Maintenance ever arriving at the aircraft the MAP function on both displays started working. Again we called Dispatch and Maintenance and concluded that we were good to takeoff. On takeoff both flight directors disappeared. We turned the flight director switches off and then on and were able to regain our flight directors. The First Officer was unable to engage the autopilot on either side and was having to hand-fly the aircraft. Passing thru 15;000 FT; we noticed a smell in the cockpit like something was burning. At the same time the flight attendants called up that they smelled something like it was burning. (They had not turned on the ovens or the coffee makers when we got the smell). Not knowing where the smell was coming from we decided to declare an emergency and return to the airport. We accomplished the 'Smoke; Fire or Fumes' QRH checklist. The flight attendants turned off the power ports and wifi and immediately searched the cabin to look for what might be causing the smell. The smell subsided as rapidly as it came without any indication of where it came from. During the return to the airport the First Officer was getting what we determined to be unreliable inputs from the flight directors. Because of declaring an emergency we requested that ARFF trucks meet us on landing and check us over before taxiing. The landing was an uneventful normal landing. Excellent job by all crewmembers and should be commended for their expertise and job well done. Crew coordination between the cabin crew and flight crew was outstanding.

Data retrieved from NASA's ASRS site as of July 2013 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.