Narrative:

A clear, perfect evening flight. I noticed the airspeed very slowly begin to drop and I thought I was losing my great tailwind. The airspeed drop, from 210 KTS to 190 KTS, was the same on the GPS as the DME, so station proximity had nothing to do with it. After a few mins, the 'gear safety bypass' lit up (next to the gear handle) and began to beep. I had never, in 1900 hours of flying mooneys, seen this light up. Since this is a ground and slow flight safety switch, I pulled the fuse to quiet the device. After a few mins I noticed the cylinder head temperature begin rising. It quickly went to red line and I quickly told center that I wanted to land immediately due to gear problems and high cylinder head temperature. I thought the gear might be in the down position or partially down since this will cause the engine temperatures to rise although there was no indication that the gear was not up. Center seemed confused that I had 2 problems and he wanted to know the nature of the gear problem. He also gave me a descent order and vectors. I was having trouble responding and complying while trying to figure out what was happening. Since my responses were poor and since I wasn't descending, the controller suggested I might be suffering from hypoxia and to check my oxygen. Despite the other problems, he was right. My oxygen line was disconnected from its plug. Finally, I used the trim wheel to lower the nose and began a very rapid descent to 8000 ft since I had no idea how long I had been without oxygen. However, the gear bypass enunciator and the high cylinder head temperatures were not in my imagination. Had I been sharper I would have recognized the problem with the trim switch sooner than I did. At 8000 ft I pushed the fuse back in for the gear bypass and the light didn't come back on. I cycled the gear and it worked fine. The cylinder head temperature was normal. Westmoreland county airport brought out fire equipment which was fine with me. I saw a few pieces of equipment near the runway and asked for permission to land. The tower advised that more equipment was coming and to continue to circle. Indeed it was. There was enough to handle a jet liner. I appreciate the assistance, but it looked like way too much equipment for a single engine aircraft, problem or not. The next morning, I circled the airport alone and without incident, then took my 2 passenger back to pne, again without incident. As of this writing I can only suspect a runaway trim situation hampered by an oxygen starved pilot. I would like to express my deepest thanks to the controller who recognized the sounds of hypoxia in my voice, and to all of those who gave of themselves on behalf of myself and my 2 children aboard. Also, I have read many times about the need for special training for high altitude and autoplt problems. I am beginning to agree. This incident also points out the need to train for emergency sits and to maintain a proper scan during the emergency. My 2000 hours represents a lot of yrs, not since training, but since good hard emergency training. That will be corrected.

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Original NASA ASRS Text

Title: PVT PLT CRUISING AT 17000 FT ON A CLR NIGHT IS SUFFERING FROM HYPOXIA AND DOESN'T YET KNOW IT. AN AIRSPD LOSS, A SEEMINGLY UNASSOCIATED GEAR PROB AND A MAXED OUT CYLINDER HEAD TEMP INDICATION ONLY CONFUSES THE PLT FURTHER. THE ZOB CTR CTLR, SUSPICIOUS OF THE PLT'S SLOW RESPONSES, ASKS THE PLT TO CHK HIS OXYGEN AND ISSUES A DSCNT CLRNC. ACFT PROCEEDS AT 8000 FT TO LBE, PA, FOR A SAFE LNDG. A RUNAWAY TRIM WAS THE CULPRIT.

Narrative: A CLR, PERFECT EVENING FLT. I NOTICED THE AIRSPD VERY SLOWLY BEGIN TO DROP AND I THOUGHT I WAS LOSING MY GREAT TAILWIND. THE AIRSPD DROP, FROM 210 KTS TO 190 KTS, WAS THE SAME ON THE GPS AS THE DME, SO STATION PROX HAD NOTHING TO DO WITH IT. AFTER A FEW MINS, THE 'GEAR SAFETY BYPASS' LIT UP (NEXT TO THE GEAR HANDLE) AND BEGAN TO BEEP. I HAD NEVER, IN 1900 HRS OF FLYING MOONEYS, SEEN THIS LIGHT UP. SINCE THIS IS A GND AND SLOW FLT SAFETY SWITCH, I PULLED THE FUSE TO QUIET THE DEVICE. AFTER A FEW MINS I NOTICED THE CYLINDER HEAD TEMP BEGIN RISING. IT QUICKLY WENT TO RED LINE AND I QUICKLY TOLD CTR THAT I WANTED TO LAND IMMEDIATELY DUE TO GEAR PROBS AND HIGH CYLINDER HEAD TEMP. I THOUGHT THE GEAR MIGHT BE IN THE DOWN POS OR PARTIALLY DOWN SINCE THIS WILL CAUSE THE ENG TEMPS TO RISE ALTHOUGH THERE WAS NO INDICATION THAT THE GEAR WAS NOT UP. CTR SEEMED CONFUSED THAT I HAD 2 PROBS AND HE WANTED TO KNOW THE NATURE OF THE GEAR PROB. HE ALSO GAVE ME A DSCNT ORDER AND VECTORS. I WAS HAVING TROUBLE RESPONDING AND COMPLYING WHILE TRYING TO FIGURE OUT WHAT WAS HAPPENING. SINCE MY RESPONSES WERE POOR AND SINCE I WASN'T DSNDING, THE CTLR SUGGESTED I MIGHT BE SUFFERING FROM HYPOXIA AND TO CHK MY OXYGEN. DESPITE THE OTHER PROBS, HE WAS RIGHT. MY OXYGEN LINE WAS DISCONNECTED FROM ITS PLUG. FINALLY, I USED THE TRIM WHEEL TO LOWER THE NOSE AND BEGAN A VERY RAPID DSCNT TO 8000 FT SINCE I HAD NO IDEA HOW LONG I HAD BEEN WITHOUT OXYGEN. HOWEVER, THE GEAR BYPASS ENUNCIATOR AND THE HIGH CYLINDER HEAD TEMPS WERE NOT IN MY IMAGINATION. HAD I BEEN SHARPER I WOULD HAVE RECOGNIZED THE PROB WITH THE TRIM SWITCH SOONER THAN I DID. AT 8000 FT I PUSHED THE FUSE BACK IN FOR THE GEAR BYPASS AND THE LIGHT DIDN'T COME BACK ON. I CYCLED THE GEAR AND IT WORKED FINE. THE CYLINDER HEAD TEMP WAS NORMAL. WESTMORELAND COUNTY ARPT BROUGHT OUT FIRE EQUIP WHICH WAS FINE WITH ME. I SAW A FEW PIECES OF EQUIP NEAR THE RWY AND ASKED FOR PERMISSION TO LAND. THE TWR ADVISED THAT MORE EQUIP WAS COMING AND TO CONTINUE TO CIRCLE. INDEED IT WAS. THERE WAS ENOUGH TO HANDLE A JET LINER. I APPRECIATE THE ASSISTANCE, BUT IT LOOKED LIKE WAY TOO MUCH EQUIP FOR A SINGLE ENG ACFT, PROB OR NOT. THE NEXT MORNING, I CIRCLED THE ARPT ALONE AND WITHOUT INCIDENT, THEN TOOK MY 2 PAX BACK TO PNE, AGAIN WITHOUT INCIDENT. AS OF THIS WRITING I CAN ONLY SUSPECT A RUNAWAY TRIM SIT HAMPERED BY AN OXYGEN STARVED PLT. I WOULD LIKE TO EXPRESS MY DEEPEST THANKS TO THE CTLR WHO RECOGNIZED THE SOUNDS OF HYPOXIA IN MY VOICE, AND TO ALL OF THOSE WHO GAVE OF THEMSELVES ON BEHALF OF MYSELF AND MY 2 CHILDREN ABOARD. ALSO, I HAVE READ MANY TIMES ABOUT THE NEED FOR SPECIAL TRAINING FOR HIGH ALT AND AUTOPLT PROBS. I AM BEGINNING TO AGREE. THIS INCIDENT ALSO POINTS OUT THE NEED TO TRAIN FOR EMER SITS AND TO MAINTAIN A PROPER SCAN DURING THE EMER. MY 2000 HRS REPRESENTS A LOT OF YRS, NOT SINCE TRAINING, BUT SINCE GOOD HARD EMER TRAINING. THAT WILL BE CORRECTED.

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.