Narrative:

After cruising at FL35.0 for approximately 1 hour, I checked the performance manual to see if we could climb to FL39.0. According to the manual we could reach and cruise at FL39.0. We requested and received a clearance to FL39.0 from ZTL, and began our climb. Upon reaching FL39.0 an indicated airspeed of approximately 150 was noted. We waited for the airspeed to increase. However, the airspeed began to decay. When the indicated airspeed reached 145-148 we advised ZTL of the fact that we would be unable to stay at FL39.0 and requested a descent back to FL35.0. We were advised that we had traffic at 1200 at FL37.0 and we would be able to descend to FL35.0 in approximately 4 min. Shortly after acknowledging this, our airspeed was 140 KTS and the speed index lights turned red, and a slight buffet began. We activated the ignition so as the help prevent engine stall. ZTL was then very busy and we were unable to advise center of our problem. We turned off the autoplt to try to regain some airspeed as the stick shaker was starting. When we uncoupled the autoplt the aircraft began to sink and we were able to maintain 38400'. At this time center frequency was clear and we advised our problem. Center turned us to 270 degree and we maintained 38400'. Shortly afterward we were cleared to FL35.0. The aircraft weight at this time was approximately 17000 pounds. Outside temperature gauge read 48 degree C. We were unable to maintain FL39.0 as I was sure we may have stalled and then been out of control, I felt that trying to maintain a slightly lower altitude was our only out until we could communication our problem with ZTL.

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Original NASA ASRS Text

Title: CPR LTT UNABLE TO MAINTAIN CRUISE ALT DSNDS BELOW CLRNC ALT CAUSING LESS THAN STANDARD SEPARATION WITH TRAFFIC IN THE AREA.

Narrative: AFTER CRUISING AT FL35.0 FOR APPROX 1 HR, I CHKED THE PERFORMANCE MANUAL TO SEE IF WE COULD CLB TO FL39.0. ACCORDING TO THE MANUAL WE COULD REACH AND CRUISE AT FL39.0. WE REQUESTED AND RECEIVED A CLRNC TO FL39.0 FROM ZTL, AND BEGAN OUR CLB. UPON REACHING FL39.0 AN INDICATED AIRSPD OF APPROX 150 WAS NOTED. WE WAITED FOR THE AIRSPD TO INCREASE. HOWEVER, THE AIRSPD BEGAN TO DECAY. WHEN THE INDICATED AIRSPD REACHED 145-148 WE ADVISED ZTL OF THE FACT THAT WE WOULD BE UNABLE TO STAY AT FL39.0 AND REQUESTED A DSNT BACK TO FL35.0. WE WERE ADVISED THAT WE HAD TFC AT 1200 AT FL37.0 AND WE WOULD BE ABLE TO DSND TO FL35.0 IN APPROX 4 MIN. SHORTLY AFTER ACKNOWLEDGING THIS, OUR AIRSPD WAS 140 KTS AND THE SPD INDEX LIGHTS TURNED RED, AND A SLIGHT BUFFET BEGAN. WE ACTIVATED THE IGNITION SO AS THE HELP PREVENT ENG STALL. ZTL WAS THEN VERY BUSY AND WE WERE UNABLE TO ADVISE CTR OF OUR PROB. WE TURNED OFF THE AUTOPLT TO TRY TO REGAIN SOME AIRSPD AS THE STICK SHAKER WAS STARTING. WHEN WE UNCOUPLED THE AUTOPLT THE ACFT BEGAN TO SINK AND WE WERE ABLE TO MAINTAIN 38400'. AT THIS TIME CTR FREQ WAS CLR AND WE ADVISED OUR PROB. CTR TURNED US TO 270 DEG AND WE MAINTAINED 38400'. SHORTLY AFTERWARD WE WERE CLRED TO FL35.0. THE ACFT WEIGHT AT THIS TIME WAS APPROX 17000 LBS. OUTSIDE TEMPERATURE GAUGE READ 48 DEG C. WE WERE UNABLE TO MAINTAIN FL39.0 AS I WAS SURE WE MAY HAVE STALLED AND THEN BEEN OUT OF CTL, I FELT THAT TRYING TO MAINTAIN A SLIGHTLY LOWER ALT WAS OUR ONLY OUT UNTIL WE COULD COM OUR PROB WITH ZTL.

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.