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Medium large transport air carrier aircraft encountered severe turbulence at FL314 ft altitude and PF could not control the aircraft. After an uncontrollable descent to FL295 ATC reclred aircraft to FL280 where the turbulence was acceptable.
| Attributes | |
| ACN | 388138 |
| Time | |
| Date | 199712 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : lfk |
| State Reference | TX |
| Altitude | msl bound lower : 29800 msl bound upper : 31000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zfw artcc : zjx |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | climbout : intermediate altitude cruise other other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | other pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 240 flight time total : 13500 flight time type : 5000 |
| ASRS Report | 388138 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter other other anomaly |
| Independent Detector | other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : regained aircraft control flight crew : declared emergency flight crew : took evasive action |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Weather |
Narrative:
While experiencing continuous light with occasional moderate chop, a climb was initiated at FL310 to FL330. After climbing about 200 ft, the turbulence intensified to continuous moderate turbulence. At approximately FL314 severe turbulence was encountered. The aircraft began an uncontrollable descent and an emergency was declared at FL298 when it became apparent the uncontrollable descent could not be arrested. ZFW cleared us to FL290 and we continued to descend to FL290. While control of aircraft returned at FL295, FL290 continued to produce moderate turbulence. Descent to FL280 resulted in an acceptable ride and flight continued uneventfully. Radar was operating at time of incident with no indication of precipitation or turbulence. Ride reports in the area at FL330 were light chop. Flight was in IMC during event and transponder code 7700 was not used.
Original NASA ASRS Text
Title: MLG ACR ACFT ENCOUNTERED SEVERE TURB AT FL314 FT ALT AND PF COULD NOT CTL THE ACFT. AFTER AN UNCTLABLE DSCNT TO FL295 ATC RECLRED ACFT TO FL280 WHERE THE TURB WAS ACCEPTABLE.
Narrative: WHILE EXPERIENCING CONTINUOUS LIGHT WITH OCCASIONAL MODERATE CHOP, A CLB WAS INITIATED AT FL310 TO FL330. AFTER CLBING ABOUT 200 FT, THE TURB INTENSIFIED TO CONTINUOUS MODERATE TURB. AT APPROX FL314 SEVERE TURB WAS ENCOUNTERED. THE ACFT BEGAN AN UNCTLABLE DSCNT AND AN EMER WAS DECLARED AT FL298 WHEN IT BECAME APPARENT THE UNCTLABLE DSCNT COULD NOT BE ARRESTED. ZFW CLRED US TO FL290 AND WE CONTINUED TO DSND TO FL290. WHILE CTL OF ACFT RETURNED AT FL295, FL290 CONTINUED TO PRODUCE MODERATE TURB. DSCNT TO FL280 RESULTED IN AN ACCEPTABLE RIDE AND FLT CONTINUED UNEVENTFULLY. RADAR WAS OPERATING AT TIME OF INCIDENT WITH NO INDICATION OF PRECIP OR TURB. RIDE RPTS IN THE AREA AT FL330 WERE LIGHT CHOP. FLT WAS IN IMC DURING EVENT AND XPONDER CODE 7700 WAS NOT USED.
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.