Narrative:

Upon taking the runway for takeoff we realized that the map display was slightly off but we thought that the map would update as we added power for takeoff. When it did not update we asked the tower for a heading and advised that we could no longer accept an RNAV departure. We departed and switched to departure. They gave us a radial to intercept. After we leveled in-flight we decided to try and align the IRS per the QRH. We lost the compasses and command bars at that point. We decided to return to ZZZ and not continue. We informed ATC and declared an emergency. They turned us around and headed us back to ZZZ. Shortly after we turned around we were informed by the aft flight attendants that there was a strong electrical burning smell in the cabin. We inform ATC of the emergency and ran through the checklist. The fumes at that point could be detected in the cockpit. As we descended the fumes dissipated rapidly. We ran the overweight landing checklist and landed. Crash fire rescue equipment equipment met us. No indications of heat. Crash fire rescue equipment followed us to the gate. Callback conversation with reporter revealed the following information: the reporter stated that the system is designed to update aircraft position on takeoff roll. The flight crew believed that this would occur when they became aware of the map shift prior to departure. When the alignment was attempted after airborne and compass information was lost; the flight crew elected to return. The reporter stated that in the future; a realignment will be attempted before taking the runway. The source of the acrid odor in the cabin could not be located or identified and remains a mystery.

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Original NASA ASRS Text

Title: MD80 FMS DISPLAY INDICATED A MAP SHIFT. FLT CREW ATTEMPTED TO ALIGN THE IRS AFTER AIRBORNE AND LOST COMPASS INFO. WHILE RETURNING FOR PRECAUTIONARY LNDG; AN ELECTRICAL BURNING ODOR WAS PRESENT IN THE CABIN.

Narrative: UPON TAKING THE RWY FOR TKOF WE REALIZED THAT THE MAP DISPLAY WAS SLIGHTLY OFF BUT WE THOUGHT THAT THE MAP WOULD UPDATE AS WE ADDED PWR FOR TKOF. WHEN IT DID NOT UPDATE WE ASKED THE TWR FOR A HDG AND ADVISED THAT WE COULD NO LONGER ACCEPT AN RNAV DEP. WE DEPARTED AND SWITCHED TO DEP. THEY GAVE US A RADIAL TO INTERCEPT. AFTER WE LEVELED INFLT WE DECIDED TO TRY AND ALIGN THE IRS PER THE QRH. WE LOST THE COMPASSES AND COMMAND BARS AT THAT POINT. WE DECIDED TO RETURN TO ZZZ AND NOT CONTINUE. WE INFORMED ATC AND DECLARED AN EMER. THEY TURNED US AROUND AND HEADED US BACK TO ZZZ. SHORTLY AFTER WE TURNED AROUND WE WERE INFORMED BY THE AFT FLT ATTENDANTS THAT THERE WAS A STRONG ELECTRICAL BURNING SMELL IN THE CABIN. WE INFORM ATC OF THE EMER AND RAN THROUGH THE CHKLIST. THE FUMES AT THAT POINT COULD BE DETECTED IN THE COCKPIT. AS WE DSNDED THE FUMES DISSIPATED RAPIDLY. WE RAN THE OVERWT LNDG CHKLIST AND LANDED. CFR EQUIP MET US. NO INDICATIONS OF HEAT. CFR FOLLOWED US TO THE GATE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE REPORTER STATED THAT THE SYSTEM IS DESIGNED TO UPDATE ACFT POSITION ON TKOF ROLL. THE FLT CREW BELIEVED THAT THIS WOULD OCCUR WHEN THEY BECAME AWARE OF THE MAP SHIFT PRIOR TO DEP. WHEN THE ALIGNMENT WAS ATTEMPTED AFTER AIRBORNE AND COMPASS INFO WAS LOST; THE FLT CREW ELECTED TO RETURN. THE REPORTER STATED THAT IN THE FUTURE; A REALIGNMENT WILL BE ATTEMPTED BEFORE TAKING THE RWY. THE SOURCE OF THE ACRID ODOR IN THE CABIN COULD NOT BE LOCATED OR IDENTIFIED AND REMAINS A MYSTERY.

Data retrieved from NASA's ASRS site as of January 2009 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.