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B757 captain reported an increasing performance windshear event on departure from sfo which resulted in a near overspeed of the flaps during the initial climb out.
| Attributes | |
| ACN | 1455916 |
| Time | |
| Date | 201706 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | SFO.Airport |
| State Reference | CA |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Initial Climb |
| Flight Plan | IFR |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Type 907 |
| Events | |
| Anomaly | Deviation - Procedural Published Material / Policy Deviation - Speed All Types Inflight Event / Encounter Weather / Turbulence |
Narrative:
Just after rotation on runway 28L in sfo; the aircraft rapidly accelerated and climbed much faster than a normal profile takeoff. There were tower reports of speed gains 15 plus knots on rotation. The winds were 260 at 28 gusting 33. I elected to go flaps 5; max blast due to windshear concerns. We had a slightly slower than normal rotation rate. Vr was 155; and at about 200 ft; I saw my speed at 177 and accelerating. I pitched the nose up higher but the speed kept accelerating. I do not know what our climb rate was. The pitch bars were trying to command a 24+ degree nose up. My first officer called out the speed and next I looked; we were close to an overspeed with the airspeed trend indicator screaming up into the red. I called for flaps up to 1; and we started our right turn. This all happened so quickly; that we were already at 800 ft by the time we started our turn. There were no other indications of a microburst; but the plane was acting and it felt like we had taken off into the increasing performance side of a burst. We continued to clean up the plane and climb out. After dodging some thunderstorms and getting above the weather; we discussed if we had overspeed the flaps. Neither of us actually saw an overspeed; but we think we might have gotten close so to err on the side of caution; we sent in a maintenance report.
Original NASA ASRS Text
Title: B757 Captain reported an increasing performance windshear event on departure from SFO which resulted in a near overspeed of the flaps during the initial climb out.
Narrative: Just after rotation on runway 28L in SFO; the aircraft rapidly accelerated and climbed much faster than a normal profile takeoff. There were tower reports of speed gains 15 plus knots on rotation. The winds were 260 at 28 gusting 33. I elected to go flaps 5; max blast due to windshear concerns. We had a slightly slower than normal rotation rate. Vr was 155; and at about 200 ft; I saw my speed at 177 and accelerating. I pitched the nose up higher but the speed kept accelerating. I do not know what our climb rate was. The pitch bars were trying to command a 24+ degree nose up. My FO called out the speed and next I looked; we were close to an overspeed with the airspeed trend indicator screaming up into the red. I called for flaps up to 1; and we started our right turn. This all happened so quickly; that we were already at 800 ft by the time we started our turn. There were no other indications of a microburst; but the plane was acting and it felt like we had taken off into the increasing performance side of a burst. We continued to clean up the plane and climb out. After dodging some thunderstorms and getting above the weather; we discussed if we had overspeed the flaps. Neither of us actually saw an overspeed; but we think we might have gotten close so to err on the side of caution; we sent in a maintenance report.
Data retrieved from NASA's ASRS site 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.