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A B737-800 at FL370 approached a stall condition as it turned and leveled following a climb. Aircraft descended approximately 400 ft during recovery.
| Attributes | |
| ACN | 754170 |
| Time | |
| Date | 200709 |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | msl single value : 36800 |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Controlling Facilities | artcc : zzz.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737-800 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other vortac |
| Flight Phase | climbout : vacating altitude |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| ASRS Report | 754170 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| ASRS Report | 754171 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude other anomaly |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | flight crew : regained aircraft control flight crew : returned to assigned altitude |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Problem Areas | Aircraft Flight Crew Human Performance |
| Primary Problem | Aircraft |
Narrative:
At FL330; ATC requested we climb to FL370 and be level by XA45Z. Vertical speed was selected. After climb was initiated; ATC instructed us to turn 15 degrees left for our climb; and upon reaching FL370 cleared direct ZZZ. At 36800 ft; I noticed airspeed dropping below selected speed bug; and advised the captain 'watch your airspeed.' at that time we were at least 5 KTS above the yellow hook. The captain selected LNAV. I believe he did this because the aircraft was starting to level off at FL370 and the airspeed was above the yellow hook. As the aircraft turned to intercept the course; with autoplt and autothrottles engaged; we felt what may have been a buffet for about 1-2 seconds. I'm not sure if the buffet was caused by the flight spoilers deploying in the bank; the light chop we were in; or the airspeed. As the wings started to roll level; we had an 'a' appear in the speed select window; indicating the airspeed had slowed into the yellow hook. The autoplt lowered the nose to protect the speed. The captain immediately disconnected the autoplt; continued to roll the wings level; and returned the aircraft to FL370. The aircraft had descended approximately 400 ft.
Original NASA ASRS Text
Title: A B737-800 AT FL370 APCHED A STALL CONDITION AS IT TURNED AND LEVELED FOLLOWING A CLB. ACFT DSNDED APPROX 400 FT DURING RECOVERY.
Narrative: AT FL330; ATC REQUESTED WE CLB TO FL370 AND BE LEVEL BY XA45Z. VERT SPD WAS SELECTED. AFTER CLB WAS INITIATED; ATC INSTRUCTED US TO TURN 15 DEGS L FOR OUR CLB; AND UPON REACHING FL370 CLRED DIRECT ZZZ. AT 36800 FT; I NOTICED AIRSPD DROPPING BELOW SELECTED SPD BUG; AND ADVISED THE CAPT 'WATCH YOUR AIRSPD.' AT THAT TIME WE WERE AT LEAST 5 KTS ABOVE THE YELLOW HOOK. THE CAPT SELECTED LNAV. I BELIEVE HE DID THIS BECAUSE THE ACFT WAS STARTING TO LEVEL OFF AT FL370 AND THE AIRSPD WAS ABOVE THE YELLOW HOOK. AS THE ACFT TURNED TO INTERCEPT THE COURSE; WITH AUTOPLT AND AUTOTHROTTLES ENGAGED; WE FELT WHAT MAY HAVE BEEN A BUFFET FOR ABOUT 1-2 SECONDS. I'M NOT SURE IF THE BUFFET WAS CAUSED BY THE FLT SPOILERS DEPLOYING IN THE BANK; THE LIGHT CHOP WE WERE IN; OR THE AIRSPD. AS THE WINGS STARTED TO ROLL LEVEL; WE HAD AN 'A' APPEAR IN THE SPD SELECT WINDOW; INDICATING THE AIRSPD HAD SLOWED INTO THE YELLOW HOOK. THE AUTOPLT LOWERED THE NOSE TO PROTECT THE SPD. THE CAPT IMMEDIATELY DISCONNECTED THE AUTOPLT; CONTINUED TO ROLL THE WINGS LEVEL; AND RETURNED THE ACFT TO FL370. THE ACFT HAD DSNDED APPROX 400 FT.
Data retrieved from NASA's ASRS site as of January 2009 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.