Narrative:

I was the pm on a visual approach backed up by the ILS to [destination]. The PF was high and fast and was unable to get stabilized passing through approximately 1000 feet. I was already concerned we were not going to get stabilized earlier on the approach. We were unable [to] mitigate our excess energy during the approach. The aircraft ahead of us called a 20 kt shear at 800 feet. Passing through 1000 feet and struggling to get established we in fact did encounter the 20 kt shear which pushed us well above our 30 flap speed; resulting in the flaps blowing up to 25 as advertised. There was a couple seconds where we thought about transitioning to a 25 flap approach. I positioned the flaps to 25 and then said 'lets go around and try this again'. The PF said 'going around flaps 20' and we executed a missed approach I believe at approximately 700 or 800 feet. At the positive rate gear up point I reached over and positioned the gear handle to up and the gear retracted normally and then we got two EICAS caution messages. The first was le (leading edge) slat disagree followed by a te (trailing edge) flap disagree caution message. I told the PF he had the aircraft and ATC and I got into the QRH and ran the appropriate checklist which basically had us match the flap handle with our current flap position and select le and te altn switches to altn and select 20 flaps. It was clear the flaps were not moving from the flaps 20 position and we had a landable configuration. Due to the short runway and current wind conditions at [destination] (080-20g30) and our fuel state we elected to divert to [an alternate] with a long runway and relatively calm winds. All checklists were completed and we diverted with no additional complications. I [advised] ATC and requested a vector direct. Our fuel at landing was 5K lbs. Maintenance reset the flaps and ran their appropriate checklist; we took off and landed at [original destination] 3 hours late uneventfully.

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Original NASA ASRS Text

Title: B757 Captain reported diverting to an alternate after experiencing a flap anomaly from overspeeding the flaps during a windshear event.

Narrative: I was the PM on a visual approach backed up by the ILS to [destination]. The PF was high and fast and was unable to get stabilized passing through approximately 1000 feet. I was already concerned we were not going to get stabilized earlier on the approach. We were unable [to] mitigate our excess energy during the approach. The aircraft ahead of us called a 20 kt shear at 800 feet. Passing through 1000 feet and struggling to get established we in fact did encounter the 20 kt shear which pushed us well above our 30 flap speed; resulting in the flaps blowing up to 25 as advertised. There was a couple seconds where we thought about transitioning to a 25 flap approach. I positioned the flaps to 25 and then said 'lets go around and try this again'. The PF said 'going around flaps 20' and we executed a missed approach I believe at approximately 700 or 800 feet. At the positive rate gear up point I reached over and positioned the gear handle to up and the gear retracted normally and then we got two EICAS caution messages. The first was LE (Leading Edge) slat disagree followed by a TE (Trailing Edge) flap disagree caution message. I told the PF he had the aircraft and ATC and I got into the QRH and ran the appropriate checklist which basically had us match the flap handle with our current flap position and select LE and TE ALTN switches to ALTN and select 20 flaps. It was clear the flaps were not moving from the flaps 20 position and we had a landable configuration. Due to the short runway and current wind conditions at [destination] (080-20G30) and our fuel state we elected to divert to [an alternate] with a long runway and relatively calm winds. All checklists were completed and we diverted with no additional complications. I [advised] ATC and requested a vector direct. Our fuel at landing was 5K lbs. Maintenance reset the flaps and ran their appropriate checklist; we took off and landed at [original destination] 3 hours late uneventfully.

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.