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A B777 flight crew experienced a significant wind direction shift, resulting in a speed being exceeded.
| Attributes | |
| ACN | 579332 |
| Time | |
| Date | 200304 |
| Day | Tue |
| Local Time Of Day | 0001 To 0600 |
| Place | |
| Locale Reference | atc facility : zdv.artcc |
| State Reference | CO |
| Altitude | msl bound lower : 36000 msl bound upper : 36100 |
| Environment | |
| Weather Elements | Windshear |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B777-200 |
| Operating Under FAR Part | Part 121 |
| 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 : 200 flight time total : 18000 flight time type : 2200 |
| ASRS Report | 579332 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | inflight encounter : weather other anomaly |
| Independent Detector | aircraft equipment other aircraft equipment : airspeed indicator other flight crewa |
| Resolutory Action | none taken : unable |
| Consequence | other |
| Supplementary | |
| Problem Areas | Weather Flight Crew Human Performance Environmental Factor |
| Primary Problem | Weather |
Narrative:
We were climbing at mach .84 to FL390. The entire climb had been in smooth air with a 70 KT tailwind as we passed FL360. Approximately FL361, the wind changed 180 degrees to a 40 KT headwind. That was an almost instantaneous change of wind component of 100 KTS. The autoplt and autothrottles could not react fast enough to prevent a 20 KT increase in indicated airspeed, which gave us a 5 KT overspd that lasted about 5 seconds. It looked and felt like the classic microburst windshear that we practice in the simulator. The flight continued normally the rest of the way to sfo. A logbook entry was made and maintenance was notified.
Original NASA ASRS Text
Title: A B777 FLT CREW EXPERIENCED A SIGNIFICANT WIND DIRECTION SHIFT, RESULTING IN A SPD BEING EXCEEDED.
Narrative: WE WERE CLBING AT MACH .84 TO FL390. THE ENTIRE CLB HAD BEEN IN SMOOTH AIR WITH A 70 KT TAILWIND AS WE PASSED FL360. APPROX FL361, THE WIND CHANGED 180 DEGS TO A 40 KT HEADWIND. THAT WAS AN ALMOST INSTANTANEOUS CHANGE OF WIND COMPONENT OF 100 KTS. THE AUTOPLT AND AUTOTHROTTLES COULD NOT REACT FAST ENOUGH TO PREVENT A 20 KT INCREASE IN INDICATED AIRSPD, WHICH GAVE US A 5 KT OVERSPD THAT LASTED ABOUT 5 SECONDS. IT LOOKED AND FELT LIKE THE CLASSIC MICROBURST WINDSHEAR THAT WE PRACTICE IN THE SIMULATOR. THE FLT CONTINUED NORMALLY THE REST OF THE WAY TO SFO. A LOGBOOK ENTRY WAS MADE AND MAINT WAS NOTIFIED.
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.