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A B757 crew, during cruise at FL370, encountered a moderate to severe mountain wave, causing an altitude variation of +200 ft, accompanied by a momentary speed increase from pt 810 mach to approximately pt 890 mach.
| Attributes | |
| ACN | 540539 |
| Time | |
| Date | 200203 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : pub.airport |
| State Reference | CO |
| Altitude | msl bound lower : 37000 msl bound upper : 37200 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv.artcc tower : cyyz.tower |
| 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 : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 540539 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter other other anomaly |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | flight crew : exited adverse environment flight crew : overrode automation |
| Consequence | other other |
| Supplementary | |
| Problem Areas | Environmental Factor Weather Flight Crew Human Performance |
| Primary Problem | Environmental Factor |
| Air Traffic Incident | Pilot Deviation |
Narrative:
While cruising at FL370 near publication, encountered moderate to severe mountain wave with autothrottles on. Aircraft began accelerating rapidly from about .810 mach to about .890 mach. During acceleration, autothrottle was slow to respond and manually overrode autothrottle to idle thrust. With idle thrust, aircraft continued to gain speed from about .855 to about .890 mach. Increase was fairly rapid. Aircraft was pitching down to maintain altitude. Aircraft climbed about 200 ft. Ride conditions were fairly smooth with just a slight rumble. Airspeed then decreased quickly to about .770 mach while throttles were manually advanced. Speed then stabilized. Entire event took about 1 1/2 mins. Remainder of flight was uneventful. Notified dispatch.
Original NASA ASRS Text
Title: A B757 CREW, DURING CRUISE AT FL370, ENCOUNTERED A MODERATE TO SEVERE MOUNTAIN WAVE, CAUSING AN ALT VARIATION OF +200 FT, ACCOMPANIED BY A MOMENTARY SPD INCREASE FROM PT 810 MACH TO APPROX PT 890 MACH.
Narrative: WHILE CRUISING AT FL370 NEAR PUB, ENCOUNTERED MODERATE TO SEVERE MOUNTAIN WAVE WITH AUTOTHROTTLES ON. ACFT BEGAN ACCELERATING RAPIDLY FROM ABOUT .810 MACH TO ABOUT .890 MACH. DURING ACCELERATION, AUTOTHROTTLE WAS SLOW TO RESPOND AND MANUALLY OVERRODE AUTOTHROTTLE TO IDLE THRUST. WITH IDLE THRUST, ACFT CONTINUED TO GAIN SPD FROM ABOUT .855 TO ABOUT .890 MACH. INCREASE WAS FAIRLY RAPID. ACFT WAS PITCHING DOWN TO MAINTAIN ALT. ACFT CLBED ABOUT 200 FT. RIDE CONDITIONS WERE FAIRLY SMOOTH WITH JUST A SLIGHT RUMBLE. AIRSPD THEN DECREASED QUICKLY TO ABOUT .770 MACH WHILE THROTTLES WERE MANUALLY ADVANCED. SPD THEN STABILIZED. ENTIRE EVENT TOOK ABOUT 1 1/2 MINS. REMAINDER OF FLT WAS UNEVENTFUL. NOTIFIED DISPATCH.
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.