Narrative:

At 41000 north 39 degrees west 62 degrees I was approaching an area of WX. I was in overcast and I did cloud conditions, complete IFR! Both radar position detected no major cell returns at higher altitudes, only smaller cell readout with antenna tilted 6-8 degrees down. However, I didn't trust the WX radar and previous aircraft had deviated at lower altitudes. I deviated approximately 3 mi to the left of track around what I interpreted to be an area of more intense moisture (more 'yellow' on colored radar than 'green'). However, as I approached to the left side of this area I noticed the clouds thickening and darker. Immediately I was in intense turbulence and heavy moisture. I had the ignition and seat belt sign already on -- no engine anti-ice required at some minus 50 degrees at 41000 ft. The left engine started rapid stalling and losing approximately 50 percent power and EPR. Airspeed started dropping slowly. I requested first officer to call new york radio for descent clearance, however, arinc communications are too slow and I had to start a shallow descent to maintain a safe airspeed. 1200- 1500 ft was lost until I flew out of major WX conditions. I immediately climbed back to 41000 ft and was able to return to random track. Problems-solutions: 1) new york radio refused prior request for track changes. 2) southern radom tracks should not be flown in summertime during peak thunderstorm activities when a northern track could be flown -- southern tracks are flown for financial reasons, not safety. 3) should have had anti-ice on even if not required -- might have also help relieve left engine stall (compressor stall). 4) radar (aircraft) system were inadequate to detect high altitude 'dry moisture' cell. 5) no ATC system to help with cell detection and allow also easy communications for storm deviations. Also pilot reports in this case were not existing.

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Original NASA ASRS Text

Title: ENG STALL RESULTING IN LOSS OF ALT.

Narrative: AT 41000 N 39 DEGS W 62 DEGS I WAS APCHING AN AREA OF WX. I WAS IN OVCST AND I DID CLOUD CONDITIONS, COMPLETE IFR! BOTH RADAR POS DETECTED NO MAJOR CELL RETURNS AT HIGHER ALTS, ONLY SMALLER CELL READOUT WITH ANTENNA TILTED 6-8 DEGS DOWN. HOWEVER, I DIDN'T TRUST THE WX RADAR AND PREVIOUS ACFT HAD DEVIATED AT LOWER ALTS. I DEVIATED APPROX 3 MI TO THE L OF TRACK AROUND WHAT I INTERPRETED TO BE AN AREA OF MORE INTENSE MOISTURE (MORE 'YELLOW' ON COLORED RADAR THAN 'GREEN'). HOWEVER, AS I APCHED TO THE L SIDE OF THIS AREA I NOTICED THE CLOUDS THICKENING AND DARKER. IMMEDIATELY I WAS IN INTENSE TURB AND HVY MOISTURE. I HAD THE IGNITION AND SEAT BELT SIGN ALREADY ON -- NO ENG ANTI-ICE REQUIRED AT SOME MINUS 50 DEGS AT 41000 FT. THE L ENG STARTED RAPID STALLING AND LOSING APPROX 50 PERCENT PWR AND EPR. AIRSPD STARTED DROPPING SLOWLY. I REQUESTED FO TO CALL NEW YORK RADIO FOR DSCNT CLRNC, HOWEVER, ARINC COMS ARE TOO SLOW AND I HAD TO START A SHALLOW DSCNT TO MAINTAIN A SAFE AIRSPD. 1200- 1500 FT WAS LOST UNTIL I FLEW OUT OF MAJOR WX CONDITIONS. I IMMEDIATELY CLBED BACK TO 41000 FT AND WAS ABLE TO RETURN TO RANDOM TRACK. PROBS-SOLUTIONS: 1) NEW YORK RADIO REFUSED PRIOR REQUEST FOR TRACK CHANGES. 2) SOUTHERN RADOM TRACKS SHOULD NOT BE FLOWN IN SUMMERTIME DURING PEAK TSTM ACTIVITIES WHEN A NORTHERN TRACK COULD BE FLOWN -- SOUTHERN TRACKS ARE FLOWN FOR FINANCIAL REASONS, NOT SAFETY. 3) SHOULD HAVE HAD ANTI-ICE ON EVEN IF NOT REQUIRED -- MIGHT HAVE ALSO HELP RELIEVE L ENG STALL (COMPRESSOR STALL). 4) RADAR (ACFT) SYS WERE INADEQUATE TO DETECT HIGH ALT 'DRY MOISTURE' CELL. 5) NO ATC SYS TO HELP WITH CELL DETECTION AND ALLOW ALSO EASY COMS FOR STORM DEVS. ALSO PLT RPTS IN THIS CASE WERE NOT EXISTING.

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.