Narrative:

The aircraft was cruising at FL410 which for its weight was the maximum altitude. We were put into a holding pattern at FL410 at a very close fix (VOR). The series of turns toward the fix and entering the pattern using autoplt and FMS (right navigation) navigation apparently caused a significant loss of airspeed. Getting the wings level did not improve the performance of the aircraft. As the speed did not improve and another pattern turn was imminent, I requested a descent from the center controller. I was concerned that the plane could no longer maintain a safe stall margin at that altitude. It became apparent that due to other holding traffic that there would be a few mins delay for a descent clearance. I deemed this unacceptable and declared an emergency for an immediate descent. Clearance was given to FL400 and then to FL390 and then FL370. As soon as we were established in descent the airspeed and performance improved to normal range. Subsequent checks of weights and speeds verified that we should have been able to maintain a safe holding pattern at FL410. My guess is that the plane was loaded heavier than the paperwork input to the onboard computer showed it to be.

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Original NASA ASRS Text

Title: FLC OF AN LGT DECLARED AN EMER TO DSND TO A LOWER ALT AFTER ATTEMPTING TO HOLD AT FL410 WHICH EXCEEDED THE PERFORMANCE CAPABILITIES OF THE ACFT. AIRSPD COULD NOT BE MAINTAINED UNTIL A LOWER ALT WAS REACHED.

Narrative: THE ACFT WAS CRUISING AT FL410 WHICH FOR ITS WT WAS THE MAX ALT. WE WERE PUT INTO A HOLDING PATTERN AT FL410 AT A VERY CLOSE FIX (VOR). THE SERIES OF TURNS TOWARD THE FIX AND ENTERING THE PATTERN USING AUTOPLT AND FMS (R NAV) NAV APPARENTLY CAUSED A SIGNIFICANT LOSS OF AIRSPD. GETTING THE WINGS LEVEL DID NOT IMPROVE THE PERFORMANCE OF THE ACFT. AS THE SPD DID NOT IMPROVE AND ANOTHER PATTERN TURN WAS IMMINENT, I REQUESTED A DSCNT FROM THE CTR CTLR. I WAS CONCERNED THAT THE PLANE COULD NO LONGER MAINTAIN A SAFE STALL MARGIN AT THAT ALT. IT BECAME APPARENT THAT DUE TO OTHER HOLDING TFC THAT THERE WOULD BE A FEW MINS DELAY FOR A DSCNT CLRNC. I DEEMED THIS UNACCEPTABLE AND DECLARED AN EMER FOR AN IMMEDIATE DSCNT. CLRNC WAS GIVEN TO FL400 AND THEN TO FL390 AND THEN FL370. AS SOON AS WE WERE ESTABLISHED IN DSCNT THE AIRSPD AND PERFORMANCE IMPROVED TO NORMAL RANGE. SUBSEQUENT CHKS OF WTS AND SPDS VERIFIED THAT WE SHOULD HAVE BEEN ABLE TO MAINTAIN A SAFE HOLDING PATTERN AT FL410. MY GUESS IS THAT THE PLANE WAS LOADED HEAVIER THAN THE PAPERWORK INPUT TO THE ONBOARD COMPUTER SHOWED IT TO BE.

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.