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An A320 crew, during cruise at FL390, encountered a severe mountain wave, causing an altitude variation of +400 ft to -1500 ft.
| Attributes | |
| ACN | 536446 |
| Time | |
| Date | 200201 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : cpr.airport |
| State Reference | WY |
| Altitude | msl bound lower : 39000 msl bound upper : 39400 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 561 |
| ASRS Report | 536446 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 210 |
| ASRS Report | 536447 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather inflight encounter other non adherence : published procedure non adherence : clearance non adherence : company policies non adherence : far other anomaly |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | controller : issued new clearance flight crew : regained aircraft control flight crew : exited adverse environment |
| Consequence | faa : reviewed incident with flight crew other other |
| Supplementary | |
| Problem Areas | Environmental Factor Weather |
| Primary Problem | Weather |
Narrative:
Cruising at FL390, mach .78, encountered severe mountain wave that resulted in overspd. Autoplt disconnected, aircraft pitched up and climbed to FL394. First officer retarded throttles to idle. As aircraft continued to climb, I extended speed brakes and applied forward stick pressure. Aircraft then pitched down and descended at a very rapid rate. Used aft stick to recover from descent, toga lock engaged and recovered at about FL375. Notified ATC, checked with flight attendants regarding condition of cabin, consulted with dispatch and continued to ord. No passenger injuries were reported, 1 flight attendant reported a stiff neck. Supplemental information from acn 536447: although we encountered only moderate turbulence, per southeast, for approximately 20-30 seconds, we were 'along for the ride,' independent of control inputs. We asked ATC for FL370, explaining our predicament to them, and they promptly granted FL370.
Original NASA ASRS Text
Title: AN A320 CREW, DURING CRUISE AT FL390, ENCOUNTERED A SEVERE MOUNTAIN WAVE, CAUSING AN ALT VARIATION OF +400 FT TO -1500 FT.
Narrative: CRUISING AT FL390, MACH .78, ENCOUNTERED SEVERE MOUNTAIN WAVE THAT RESULTED IN OVERSPD. AUTOPLT DISCONNECTED, ACFT PITCHED UP AND CLBED TO FL394. FO RETARDED THROTTLES TO IDLE. AS ACFT CONTINUED TO CLB, I EXTENDED SPD BRAKES AND APPLIED FORWARD STICK PRESSURE. ACFT THEN PITCHED DOWN AND DSNDED AT A VERY RAPID RATE. USED AFT STICK TO RECOVER FROM DSCNT, TOGA LOCK ENGAGED AND RECOVERED AT ABOUT FL375. NOTIFIED ATC, CHKED WITH FLT ATTENDANTS REGARDING CONDITION OF CABIN, CONSULTED WITH DISPATCH AND CONTINUED TO ORD. NO PAX INJURIES WERE RPTED, 1 FLT ATTENDANT RPTED A STIFF NECK. SUPPLEMENTAL INFO FROM ACN 536447: ALTHOUGH WE ENCOUNTERED ONLY MODERATE TURB, PER SE, FOR APPROX 20-30 SECONDS, WE WERE 'ALONG FOR THE RIDE,' INDEPENDENT OF CTL INPUTS. WE ASKED ATC FOR FL370, EXPLAINING OUR PREDICAMENT TO THEM, AND THEY PROMPTLY GRANTED FL370.
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.