B757 flight crew experience an approach to stall during leveloff at FL410 due to their procedure used to climb and level off near the aircraft's maximum cruising altitude.

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Attributes
ACN	535873
Time
Date	200201
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bff.airport
State Reference	NE
Altitude	msl bound lower : 37000 msl bound upper : 41000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 110 flight time total : 12500 flight time type : 3500
ASRS Report	535873
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	inflight encounter : turbulence non adherence : published procedure other anomaly
Independent Detector	aircraft equipment other aircraft equipment : air speed ind. other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : regained aircraft control other
Supplementary
Problem Areas	Weather Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance

Narrative:

Had a bit of light turbulence at FL370. FMC indicated our maximum altitude capable was FL415, so we requested FL410 to find a smoother ride. Aircraft climbed normally to FL410 and about 1 min after leveling off, our speed was back at .710 mach. I brought this to the captain's attention and he added maximum thrust which didn't help increase or maintain our airspeed. I called center to request a block fro FL410-FL390, which was approved. At this time, we could feel initial stall buffeting. The captain disconnected the autoplt and descended to FL400 where the aircraft performed normally maintaining economy cruise of .79 mach. FMC maximum altitude then varied from FL409 to FL415. Suspect cause of our getting behind the power curve came through a prompt climb to FL410 and the autothrottles retarding power towards idle after leveloff to maintain economy speed. Autothrottle was likely slow to re-establish cruise power in a timely fashion, thus getting behind the power curve. In retrospect, the crew caught this in time, but could have intervened sooner.

Original NASA ASRS Text

Title: B757 FLC EXPERIENCE AN APCH TO STALL DURING LEVELOFF AT FL410 DUE TO THEIR PROC USED TO CLB AND LEVEL OFF NEAR THE ACFT'S MAX CRUISING ALT.

Narrative: HAD A BIT OF LIGHT TURB AT FL370. FMC INDICATED OUR MAX ALT CAPABLE WAS FL415, SO WE REQUESTED FL410 TO FIND A SMOOTHER RIDE. ACFT CLBED NORMALLY TO FL410 AND ABOUT 1 MIN AFTER LEVELING OFF, OUR SPD WAS BACK AT .710 MACH. I BROUGHT THIS TO THE CAPT'S ATTN AND HE ADDED MAX THRUST WHICH DIDN'T HELP INCREASE OR MAINTAIN OUR AIRSPD. I CALLED CTR TO REQUEST A BLOCK FRO FL410-FL390, WHICH WAS APPROVED. AT THIS TIME, WE COULD FEEL INITIAL STALL BUFFETING. THE CAPT DISCONNECTED THE AUTOPLT AND DSNDED TO FL400 WHERE THE ACFT PERFORMED NORMALLY MAINTAINING ECONOMY CRUISE OF .79 MACH. FMC MAX ALT THEN VARIED FROM FL409 TO FL415. SUSPECT CAUSE OF OUR GETTING BEHIND THE PWR CURVE CAME THROUGH A PROMPT CLB TO FL410 AND THE AUTOTHROTTLES RETARDING PWR TOWARDS IDLE AFTER LEVELOFF TO MAINTAIN ECONOMY SPD. AUTOTHROTTLE WAS LIKELY SLOW TO RE-ESTABLISH CRUISE PWR IN A TIMELY FASHION, THUS GETTING BEHIND THE PWR CURVE. IN RETROSPECT, THE CREW CAUGHT THIS IN TIME, BUT COULD HAVE INTERVENED SOONER.

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.