Narrative:

We were operating flight to cmh. Prior to takeoff, dispatch reported moderate chop from FL290 to FL330 in the vicinity of crg VOR. During our climb, we experienced chop and heard numerous reports of rough rides from other aircraft and ATC. There were higher cirrus clouds to the west of us that extended up to roughly FL370-FL390. Winds aloft were from the west at over 100 KTS. Our filed altitude was FL390. During our climb, ZJX offered us FL370 or FL410, saying FL390 was unavailable. We asked for ride reports and were told that the higher altitudes were smoother than lower, although no one was at FL410 to five a ride report. The FMC showed optimum altitude of FL395, maximum altitude of FL410. We opted to climb to FL410, trying to get above the cirrus and the rougher rides below. After announcing that we would accept FL410, ZJX asked how long it would take to get there. We turned to the climb page on the FMC, plugged in FL410, and responded with the time that the FMC calculated. ZJX then cleared us to FL410 but to do it in that allotted time. After climbing through approximately FL390, ZJX asked us to maintain at least 1000 FPM in the climb to FL410. While climbing at 1000 FPM, our mach decreased from .785 mach to roughly .720 mach. We decreased our climb rate, trying to get our speed back up. Just prior to reaching FL410, with our speed low and the aircraft barely climbing, I think we encountered some light chop or light wave action, causing our speed to decrease more. The autoplt reverted to level change and began a descent. I asked ZJX for a lower altitude. He was unable to issue one because of oncoming traffic at FL390. I told him that we were unable to maintain FL410 and that we needed lower. Again he told us to maintain FL410 because of traffic, and that we couldn't descend unless we declared an emergency. By now our speed was slowing into the minimum maneuvering arc on the masi. With climb power set, we were still descending away from FL410 at 300-400 FPM. There was no stall nor buffet. The HUD showed the angle of attack limit indicator was within 4 degrees of our pitch attitude. I declared an emergency and told ZJX that we were descending out of FL410. ZJX quickly gave us a left turn and descent clearance to FL370. They then gave the oncoming traffic at FL390 a turn away from us. They did a great job of keeping us separated. All flight parameters quickly returned to normal as soon as we started down. Once level at FL370, I canceled my emergency authority/authorized with ZJX and continued on. Our parameters at FL410 were 122200 pounds, -58 tat, speed .785 mach. The opc showed that we had 1.3G maneuvering with low and high speed limits of 207-244 KTS, or .709 - .822 mach. Under ideal conditions, FL410 would have been fine. If we had been at .785 mach, light chop, wave action or airspeed fluctuations would have been manageable and acceptable. But by climbing at 1000 FPM, we allowed our speed to decrease from .785 to roughly .720. Now that our speed was low, we were too high, too heavy and too underpwred to accelerate out of the situation that we were in. Supplemental information from acn 608655: I don't recall the exact altitude where our mach and climb began to deteriorate, but out of FL400 I reduced vertical climb to 1000 FPM and around 40.7 to 500 FPM and at the same time made the comment or remark about needing a lower altitude. It was at this time the mach suddenly decreased, maybe a bump or temperature change. The aircraft reverted to level change and began descending. Prevention: hindsight is a wonderful thing to be able to reflect on and know the things you could or should have done differently. 1) not accepting the climb to FL410. 2) climb on profile and on speed. 3) ask for a course change to allow for a normal climb. 4) recognize sooner the trend and take the appropriate action. Lesson well learned.

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Original NASA ASRS Text

Title: B737-700 FLT DECLARED AN EMER WHEN FLT CREW REALIZES THAT ACFT CANNOT MAINTAIN FL410 AT A REDUCED MACH AFTER PASSING CRG, FL.

Narrative: WE WERE OPERATING FLT TO CMH. PRIOR TO TKOF, DISPATCH RPTED MODERATE CHOP FROM FL290 TO FL330 IN THE VICINITY OF CRG VOR. DURING OUR CLB, WE EXPERIENCED CHOP AND HEARD NUMEROUS RPTS OF ROUGH RIDES FROM OTHER ACFT AND ATC. THERE WERE HIGHER CIRRUS CLOUDS TO THE W OF US THAT EXTENDED UP TO ROUGHLY FL370-FL390. WINDS ALOFT WERE FROM THE W AT OVER 100 KTS. OUR FILED ALT WAS FL390. DURING OUR CLB, ZJX OFFERED US FL370 OR FL410, SAYING FL390 WAS UNAVAILABLE. WE ASKED FOR RIDE RPTS AND WERE TOLD THAT THE HIGHER ALTS WERE SMOOTHER THAN LOWER, ALTHOUGH NO ONE WAS AT FL410 TO FIVE A RIDE RPT. THE FMC SHOWED OPTIMUM ALT OF FL395, MAX ALT OF FL410. WE OPTED TO CLB TO FL410, TRYING TO GET ABOVE THE CIRRUS AND THE ROUGHER RIDES BELOW. AFTER ANNOUNCING THAT WE WOULD ACCEPT FL410, ZJX ASKED HOW LONG IT WOULD TAKE TO GET THERE. WE TURNED TO THE CLB PAGE ON THE FMC, PLUGGED IN FL410, AND RESPONDED WITH THE TIME THAT THE FMC CALCULATED. ZJX THEN CLRED US TO FL410 BUT TO DO IT IN THAT ALLOTTED TIME. AFTER CLBING THROUGH APPROX FL390, ZJX ASKED US TO MAINTAIN AT LEAST 1000 FPM IN THE CLB TO FL410. WHILE CLBING AT 1000 FPM, OUR MACH DECREASED FROM .785 MACH TO ROUGHLY .720 MACH. WE DECREASED OUR CLB RATE, TRYING TO GET OUR SPD BACK UP. JUST PRIOR TO REACHING FL410, WITH OUR SPD LOW AND THE ACFT BARELY CLBING, I THINK WE ENCOUNTERED SOME LIGHT CHOP OR LIGHT WAVE ACTION, CAUSING OUR SPD TO DECREASE MORE. THE AUTOPLT REVERTED TO LEVEL CHANGE AND BEGAN A DSCNT. I ASKED ZJX FOR A LOWER ALT. HE WAS UNABLE TO ISSUE ONE BECAUSE OF ONCOMING TFC AT FL390. I TOLD HIM THAT WE WERE UNABLE TO MAINTAIN FL410 AND THAT WE NEEDED LOWER. AGAIN HE TOLD US TO MAINTAIN FL410 BECAUSE OF TFC, AND THAT WE COULDN'T DSND UNLESS WE DECLARED AN EMER. BY NOW OUR SPD WAS SLOWING INTO THE MINIMUM MANEUVERING ARC ON THE MASI. WITH CLB PWR SET, WE WERE STILL DSNDING AWAY FROM FL410 AT 300-400 FPM. THERE WAS NO STALL NOR BUFFET. THE HUD SHOWED THE ANGLE OF ATTACK LIMIT INDICATOR WAS WITHIN 4 DEGS OF OUR PITCH ATTITUDE. I DECLARED AN EMER AND TOLD ZJX THAT WE WERE DSNDING OUT OF FL410. ZJX QUICKLY GAVE US A L TURN AND DSCNT CLRNC TO FL370. THEY THEN GAVE THE ONCOMING TFC AT FL390 A TURN AWAY FROM US. THEY DID A GREAT JOB OF KEEPING US SEPARATED. ALL FLT PARAMETERS QUICKLY RETURNED TO NORMAL AS SOON AS WE STARTED DOWN. ONCE LEVEL AT FL370, I CANCELED MY EMER AUTH WITH ZJX AND CONTINUED ON. OUR PARAMETERS AT FL410 WERE 122200 LBS, -58 TAT, SPD .785 MACH. THE OPC SHOWED THAT WE HAD 1.3G MANEUVERING WITH LOW AND HIGH SPD LIMITS OF 207-244 KTS, OR .709 - .822 MACH. UNDER IDEAL CONDITIONS, FL410 WOULD HAVE BEEN FINE. IF WE HAD BEEN AT .785 MACH, LIGHT CHOP, WAVE ACTION OR AIRSPD FLUCTUATIONS WOULD HAVE BEEN MANAGEABLE AND ACCEPTABLE. BUT BY CLBING AT 1000 FPM, WE ALLOWED OUR SPD TO DECREASE FROM .785 TO ROUGHLY .720. NOW THAT OUR SPD WAS LOW, WE WERE TOO HIGH, TOO HVY AND TOO UNDERPWRED TO ACCELERATE OUT OF THE SIT THAT WE WERE IN. SUPPLEMENTAL INFO FROM ACN 608655: I DON'T RECALL THE EXACT ALT WHERE OUR MACH AND CLB BEGAN TO DETERIORATE, BUT OUT OF FL400 I REDUCED VERT CLB TO 1000 FPM AND AROUND 40.7 TO 500 FPM AND AT THE SAME TIME MADE THE COMMENT OR REMARK ABOUT NEEDING A LOWER ALT. IT WAS AT THIS TIME THE MACH SUDDENLY DECREASED, MAYBE A BUMP OR TEMP CHANGE. THE ACFT REVERTED TO LEVEL CHANGE AND BEGAN DSNDING. PREVENTION: HINDSIGHT IS A WONDERFUL THING TO BE ABLE TO REFLECT ON AND KNOW THE THINGS YOU COULD OR SHOULD HAVE DONE DIFFERENTLY. 1) NOT ACCEPTING THE CLB TO FL410. 2) CLB ON PROFILE AND ON SPD. 3) ASK FOR A COURSE CHANGE TO ALLOW FOR A NORMAL CLB. 4) RECOGNIZE SOONER THE TREND AND TAKE THE APPROPRIATE ACTION. LESSON WELL LEARNED.

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.