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Aviation Safety Reporting System
|Local Time Of Day
|1801 To 2400
|airport : zzz.airport
|msl single value : 21000
|artcc : zzz.artcc
|common carrier : air carrier
|Make Model Name
|Operating Under FAR Part
|descent : intermediate altitude
|company : air carrier
|flight crew : captain
oversight : pic
|pilot : atp
|flight time last 90 days : 240
flight time total : 11400
flight time type : 3000
|company : air carrier
|flight crew : first officer
|aircraft equipment problem : critical
|other flight crewa
other flight crewb
|flight crew : landed in emergency condition
flight crew : declared emergency
We took off and were en route to ZZZ. During the arrival ATC gave us instructions to hold. While we were in the holding pattern I noticed that it was getting warm in the cockpit. I asked the first officer to cool it down a bit. After waiting a few mins for the cockpit to cool down I noticed that it was actually getting warmer; even hot. I asked the first officer if he felt warm and he agreed. He again attempted to cool down the cockpit. All attempts to cool the cockpit failed. We noticed that the needle for the left air conditioning pack valve was in the full cold position; with the system in automatic; but the air conditioning system was blowing hot air. We attempted to move the valve manually but the needle appeared to be stuck in the full cold position. We looked for an appropriate checklist to run but didn't find anything that fit this situation. We called back to the flight attendants and asked if they were getting warm. Initially they said 'no.' but then a few mins later they called back and said they felt a little warmer. Meanwhile in the cockpit it was starting to get uncomfortable. About this time ATC cleared us out of the holding pattern and was giving us vectors. As we were attempting to troubleshoot the problem the first officer and myself started to notice a smoldering; burning smell. At that time I decided it was time to get the plane on the ground immediately. We declared an emergency with ATC; sped up the airplane and headed directly for ZZZ. As we accelerated up to 300 KTS (we had been doing 240 KTS in the holding pattern) we noticed that the airflow in the cockpit started to cool down. It was still blowing warm air but not nearly as hot as before. Also the smell had largely gone away. This is the status that remained until we flew an approach and landed. We had the fire chief look us over and when he gave us the 'thumbs up' we taxied back to the gate uneventfully and deplaned the passenger. Anytime I smell something burning in an airplane I think it's a good idea to land the plane. One thing we could have done sooner; even though there was no checklist to follow; would have been to turn off the left pack. It seems obvious but for whatever reason we never did get the left pack off.
Original NASA ASRS Text
Title: MD88 FLT CREW DECLARES EMER AND LANDS WHEN UNEXPLAINED HOT AIR AND BURNING ODORS EMANATE FROM THE AIR CONDITIONING SYS.
Narrative: WE TOOK OFF AND WERE ENRTE TO ZZZ. DURING THE ARR ATC GAVE US INSTRUCTIONS TO HOLD. WHILE WE WERE IN THE HOLDING PATTERN I NOTICED THAT IT WAS GETTING WARM IN THE COCKPIT. I ASKED THE FO TO COOL IT DOWN A BIT. AFTER WAITING A FEW MINS FOR THE COCKPIT TO COOL DOWN I NOTICED THAT IT WAS ACTUALLY GETTING WARMER; EVEN HOT. I ASKED THE FO IF HE FELT WARM AND HE AGREED. HE AGAIN ATTEMPTED TO COOL DOWN THE COCKPIT. ALL ATTEMPTS TO COOL THE COCKPIT FAILED. WE NOTICED THAT THE NEEDLE FOR THE L AIR CONDITIONING PACK VALVE WAS IN THE FULL COLD POS; WITH THE SYS IN AUTO; BUT THE AIR CONDITIONING SYS WAS BLOWING HOT AIR. WE ATTEMPTED TO MOVE THE VALVE MANUALLY BUT THE NEEDLE APPEARED TO BE STUCK IN THE FULL COLD POS. WE LOOKED FOR AN APPROPRIATE CHKLIST TO RUN BUT DIDN'T FIND ANYTHING THAT FIT THIS SITUATION. WE CALLED BACK TO THE FLT ATTENDANTS AND ASKED IF THEY WERE GETTING WARM. INITIALLY THEY SAID 'NO.' BUT THEN A FEW MINS LATER THEY CALLED BACK AND SAID THEY FELT A LITTLE WARMER. MEANWHILE IN THE COCKPIT IT WAS STARTING TO GET UNCOMFORTABLE. ABOUT THIS TIME ATC CLRED US OUT OF THE HOLDING PATTERN AND WAS GIVING US VECTORS. AS WE WERE ATTEMPTING TO TROUBLESHOOT THE PROB THE FO AND MYSELF STARTED TO NOTICE A SMOLDERING; BURNING SMELL. AT THAT TIME I DECIDED IT WAS TIME TO GET THE PLANE ON THE GND IMMEDIATELY. WE DECLARED AN EMER WITH ATC; SPED UP THE AIRPLANE AND HEADED DIRECTLY FOR ZZZ. AS WE ACCELERATED UP TO 300 KTS (WE HAD BEEN DOING 240 KTS IN THE HOLDING PATTERN) WE NOTICED THAT THE AIRFLOW IN THE COCKPIT STARTED TO COOL DOWN. IT WAS STILL BLOWING WARM AIR BUT NOT NEARLY AS HOT AS BEFORE. ALSO THE SMELL HAD LARGELY GONE AWAY. THIS IS THE STATUS THAT REMAINED UNTIL WE FLEW AN APCH AND LANDED. WE HAD THE FIRE CHIEF LOOK US OVER AND WHEN HE GAVE US THE 'THUMBS UP' WE TAXIED BACK TO THE GATE UNEVENTFULLY AND DEPLANED THE PAX. ANYTIME I SMELL SOMETHING BURNING IN AN AIRPLANE I THINK IT'S A GOOD IDEA TO LAND THE PLANE. ONE THING WE COULD HAVE DONE SOONER; EVEN THOUGH THERE WAS NO CHKLIST TO FOLLOW; WOULD HAVE BEEN TO TURN OFF THE L PACK. IT SEEMS OBVIOUS BUT FOR WHATEVER REASON WE NEVER DID GET THE L PACK OFF.
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.