Narrative:

At 37000 ft, 100 mi east of rno we had a right air conditioning duct overheat. We went through that procedure. About 3 mins later we had an aft cargo smoke warning. We went through that procedure. The smoke light stayed on, aft cargo temperature 60 degree F. We had the flight attendants check for smoke in the cabin, and got dispatch and maintenance control on the line. The flight attendant said there was a faint smell of smoke in the aft cabin. I decided to declare an emergency and divert to rno (dispatcher agreed). We told the flight attendant it was a red emergency. On descent the flight attendant said there was no longer a smell of smoke in the cabin, aft cargo temperature still 60 degree F. Smoke warning went out. After the flight attendant briefed for an emergency evacuate/evacuation, I made a PA explaining that we were not going to evacuate/evacuation as soon as we landed. Instead we would have the firemen visually check out the aircraft on the ground, and if there was no smoke inside or outside the aircraft we would then taxi to the gate and deplane. The firemen visually checked the aft cargo area out on the ground and there was no smoke inside or outside the aircraft. The copilot told the people to remain seated and we taxied to the gate. After deplaning all the people, we opened the aft cargo with the fire fighters and their hoses standing by. There was no evidence of smoke or fire in the aft cargo. My guess is that the duct overheat caused the smoke smell in the cabin and the aft cargo smoke warning to go off.

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Original NASA ASRS Text

Title: FLC OF AN LGT DECLARED AN EMER AFTER RPTED CABIN SMOKE SMELL AND AN AFT CARGO OVERHEAT WARNING. THE ACFT DIVERTED TO LAND AT THE NEAREST APPROPRIATE ARPT.

Narrative: AT 37000 FT, 100 MI E OF RNO WE HAD A R AIR CONDITIONING DUCT OVERHEAT. WE WENT THROUGH THAT PROC. ABOUT 3 MINS LATER WE HAD AN AFT CARGO SMOKE WARNING. WE WENT THROUGH THAT PROC. THE SMOKE LIGHT STAYED ON, AFT CARGO TEMP 60 DEG F. WE HAD THE FLT ATTENDANTS CHK FOR SMOKE IN THE CABIN, AND GOT DISPATCH AND MAINT CTL ON THE LINE. THE FLT ATTENDANT SAID THERE WAS A FAINT SMELL OF SMOKE IN THE AFT CABIN. I DECIDED TO DECLARE AN EMER AND DIVERT TO RNO (DISPATCHER AGREED). WE TOLD THE FLT ATTENDANT IT WAS A RED EMER. ON DSCNT THE FLT ATTENDANT SAID THERE WAS NO LONGER A SMELL OF SMOKE IN THE CABIN, AFT CARGO TEMP STILL 60 DEG F. SMOKE WARNING WENT OUT. AFTER THE FLT ATTENDANT BRIEFED FOR AN EMER EVAC, I MADE A PA EXPLAINING THAT WE WERE NOT GOING TO EVAC AS SOON AS WE LANDED. INSTEAD WE WOULD HAVE THE FIREMEN VISUALLY CHK OUT THE ACFT ON THE GND, AND IF THERE WAS NO SMOKE INSIDE OR OUTSIDE THE ACFT WE WOULD THEN TAXI TO THE GATE AND DEPLANE. THE FIREMEN VISUALLY CHKED THE AFT CARGO AREA OUT ON THE GND AND THERE WAS NO SMOKE INSIDE OR OUTSIDE THE ACFT. THE COPLT TOLD THE PEOPLE TO REMAIN SEATED AND WE TAXIED TO THE GATE. AFTER DEPLANING ALL THE PEOPLE, WE OPENED THE AFT CARGO WITH THE FIRE FIGHTERS AND THEIR HOSES STANDING BY. THERE WAS NO EVIDENCE OF SMOKE OR FIRE IN THE AFT CARGO. MY GUESS IS THAT THE DUCT OVERHEAT CAUSED THE SMOKE SMELL IN THE CABIN AND THE AFT CARGO SMOKE WARNING TO GO OFF.

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.