Narrative:

We were #3 for arrival into houston sequenced behind a company aircraft and another carrier. Both of the preceding aircraft reported 'moderate chop' down the ILS in moderate precipitation. Two areas of weather were moving toward hou and the gap between them was roughly where the ILS lay. The area of weather to the south indicated some heavy precipitation but the traffic ahead gave no indication that the ride would be anything more than a bumpy one. Autopilot was on and coupled to ILS. Outside of the FAF; our aircraft encountered severe turbulence and/or windshear/microburst. The plane was shaken violently and also pitched up and then down in rapid succession. The aircraft did not provide us with a windshear alert or warning. As aircraft was in a nose down attitude trying to recapture the GS; the autopilot was disconnected; and I began the go-around/missed approach procedure. We were gear down and flaps 5 degrees or 15 degrees. The captain and I could not recall which; as we discussed the event later. While executing the missed approach procedure; the plane lost airspeed and began to sink. Go-around thrust was applied as the procedure began but the windshear seemed to be sapping our airspeed and pushing us straight down. Nose was 15 degrees up; +/-5 degrees due to turbulence. The airplane stayed in this general attitude for several seconds and then began to recover. I do remember slightly lowering the nose in an effort to recoup some airspeed. As recovery happened; airspeed rocketed into the 230 KT range. This was all occurring as we were cleaning up the airplane as best we could in accordance with missed approach procedures. Confusion in the cockpit was amplified at this point as we were both unsure if we were battling severe turbulence; windshear/microburst or all of these elements. This led to portions of 2 different procedures (go-around/missed approach and windshear recovery) being utilized with some portions being overlooked. We were unsure whether to maintain current configuration 'a la windshear' recovery or to clean up according to the missed approach procedure. This confusion was a direct result of the timing when things started to go awry. We informed hou tower that we were going missed and would not be flying the published missed as that navigation path now lay directly in the weather that we were trying to get away from. We turned to a more westerly heading and climbed through 3;000 ft when the tower asked us to climb and maintain 3;000 ft. We informed him that we were level at 3;500 ft and would return to 3;000 ft as soon as possible. After several moments; tower handed us off to departure and we informed them we were diverting. The flight -- arrival and landing -- was uneventful. I think we should have been more vigilant with weather avoidance. The cells in the area were essentially converging on the airport and we were attempting to beat the weather. Our schedule had been changed from a pretty standard duty day to a 14-hour duty day. This I'm sure was subconsciously pressuring us to try and get in so as to avoid an even longer day or yet another change of plan. I think we forced the issue and the result was a missed approach and divert. Regarding the specific procedure; I think it was just bad timing. I'm convinced we encountered windshear at some point; but I do not know if it started the event or became an element after we had initiated the missed approach. This; as stated before; led to a hodgepodge procedure being used. We knew we needed to get moving in the right direction both laterally and vertically and did what it took to make that happen. The result was an effective recovery but one that was sloppy and left us with questions about what exactly had happened.

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Original NASA ASRS Text

Title: B737NG First Officer relates unexpected encounter with windshear and/or microburst on approach to HOU.

Narrative: We were #3 for arrival into Houston sequenced behind a Company aircraft and another carrier. Both of the preceding aircraft reported 'moderate chop' down the ILS in moderate precipitation. Two areas of weather were moving toward HOU and the gap between them was roughly where the ILS lay. The area of weather to the south indicated some heavy precipitation but the traffic ahead gave no indication that the ride would be anything more than a bumpy one. Autopilot was on and coupled to ILS. Outside of the FAF; our aircraft encountered severe turbulence and/or windshear/microburst. The plane was shaken violently and also pitched up and then down in rapid succession. The aircraft did not provide us with a windshear alert or warning. As aircraft was in a nose down attitude trying to recapture the GS; the autopilot was disconnected; and I began the go-around/missed approach procedure. We were gear down and flaps 5 degrees or 15 degrees. The Captain and I could not recall which; as we discussed the event later. While executing the missed approach procedure; the plane lost airspeed and began to sink. Go-around thrust was applied as the procedure began but the windshear seemed to be sapping our airspeed and pushing us straight down. Nose was 15 degrees up; +/-5 degrees due to turbulence. The airplane stayed in this general attitude for several seconds and then began to recover. I do remember slightly lowering the nose in an effort to recoup some airspeed. As recovery happened; airspeed rocketed into the 230 KT range. This was all occurring as we were cleaning up the airplane as best we could in accordance with missed approach procedures. Confusion in the cockpit was amplified at this point as we were both unsure if we were battling severe turbulence; windshear/microburst or all of these elements. This led to portions of 2 different procedures (go-around/missed approach and windshear recovery) being utilized with some portions being overlooked. We were unsure whether to maintain current configuration 'a la windshear' recovery or to clean up according to the missed approach procedure. This confusion was a direct result of the timing when things started to go awry. We informed HOU Tower that we were going missed and would not be flying the published missed as that navigation path now lay directly in the weather that we were trying to get away from. We turned to a more westerly heading and climbed through 3;000 FT when the Tower asked us to climb and maintain 3;000 FT. We informed him that we were level at 3;500 FT and would return to 3;000 FT as soon as possible. After several moments; Tower handed us off to Departure and we informed them we were diverting. The flight -- arrival and landing -- was uneventful. I think we should have been more vigilant with weather avoidance. The cells in the area were essentially converging on the airport and we were attempting to beat the weather. Our schedule had been changed from a pretty standard duty day to a 14-hour duty day. This I'm sure was subconsciously pressuring us to try and get in so as to avoid an even longer day or yet another change of plan. I think we forced the issue and the result was a missed approach and divert. Regarding the specific procedure; I think it was just bad timing. I'm convinced we encountered windshear at some point; but I do not know if it started the event or became an element after we had initiated the missed approach. This; as stated before; led to a hodgepodge procedure being used. We knew we needed to get moving in the right direction both laterally and vertically and did what it took to make that happen. The result was an effective recovery but one that was sloppy and left us with questions about what exactly had happened.

Data retrieved from NASA's ASRS site as of April 2012 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.