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Light transport experiences loss of aircraft control due to wake turbulence behind widebody transport.
| Attributes | |
| ACN | 156987 |
| Time | |
| Date | 199009 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : sea |
| State Reference | WA |
| Altitude | msl bound lower : 10000 msl bound upper : 11000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : sea |
| Operator | common carrier : air carrier |
| Make Model Name | Light Transport, Low Wing, 2 Turboprop Eng |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Widebody, Low Wing, 4 Turbojet Eng |
| Navigation In Use | Other |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : cfi pilot : instrument pilot : atp pilot : commercial |
| Experience | flight time last 90 days : 400 flight time total : 4200 flight time type : 1200 |
| ASRS Report | 156987 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : commercial |
| Events | |
| Anomaly | inflight encounter other |
| Independent Detector | other flight crewa |
| Resolutory Action | controller : issued new clearance none taken : detected after the fact |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
We were sequenced 7 mi behind a widebody transport. We were at 10000' and the widebody transport at 11000'. The widebody transport was given a descent. A short time after that, we encountered the wake turbulence from the widebody transport. It was unmistakable since the air was smooth. The wake turbulence caused the aircraft to buffet and wallow. Aileron control was partially ineffective. We immediately climbed to get out of the wake and requested a higher altitude for wake avoidance. We were given 11000'. No injuries or damage was incurred. The wake turbulence would be classified as moderate. The sep, although initially 7 mi, was probably reduced at the time of the wake encounter, and the winds at that altitude seemed to be calm.
Original NASA ASRS Text
Title: LTT EXPERIENCES LOSS OF ACFT CTL DUE TO WAKE TURBULENCE BEHIND WDB.
Narrative: WE WERE SEQUENCED 7 MI BEHIND A WDB. WE WERE AT 10000' AND THE WDB AT 11000'. THE WDB WAS GIVEN A DSNT. A SHORT TIME AFTER THAT, WE ENCOUNTERED THE WAKE TURB FROM THE WDB. IT WAS UNMISTAKABLE SINCE THE AIR WAS SMOOTH. THE WAKE TURB CAUSED THE ACFT TO BUFFET AND WALLOW. AILERON CTL WAS PARTIALLY INEFFECTIVE. WE IMMEDIATELY CLBED TO GET OUT OF THE WAKE AND REQUESTED A HIGHER ALT FOR WAKE AVOIDANCE. WE WERE GIVEN 11000'. NO INJURIES OR DAMAGE WAS INCURRED. THE WAKE TURB WOULD BE CLASSIFIED AS MODERATE. THE SEP, ALTHOUGH INITIALLY 7 MI, WAS PROBABLY REDUCED AT THE TIME OF THE WAKE ENCOUNTER, AND THE WINDS AT THAT ALT SEEMED TO BE CALM.
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.