Narrative:

As we approached iad; I was pilot flying as captain; and iad ATIS showed ILS 1C approaches in use. But upon contacting potomac approach; we were told to expect an ILS 1R approach; circle-to-land 30. Weather was good VFR; but winds were strong and gusty out of the northwest; approximately 320@23g32. We briefed and planned for that approach. As we were on about a 15 mile final; updated winds were about the same; just a little stronger; but did not sound particularly dangerous. We discussed a plan for the approach; and where and when I would perform the necessary alignment maneuvers. Tower told us to maintain 180 KTS until turning base; and to maintain runway centerline until within 3 DME. I was hand-flying the last couple of thousand feet of the approach in anticipation of the large turn maneuver for the landing runway. We flew the ILS approach to just inside 3 DME; and were about to turn to the runway 30 final when we received a reactive windshear alert. I initiated a go-around; and just after the throttles moved forward; I began to climb straight ahead. We got a series of fairly quick wind gusts as we began the climb; and the airspeed increased rapidly. I began to reduce power as we were assured of exiting the windshear (the warning had stopped sounding); and I noticed we had a momentary overspeed on the flaps. I had been mindful of the varying airspeed; but mostly concerned about dropping below a safe speed; not expecting as much of an increase as we ended up with. I don't know the exact maximum speed or the time we were at that speed; but it was definitely only a short time and a small overspeed; although I did see a very short message load relief on the flap indicator. I reduced power and began retracting flaps immediately after that; as soon as we were no longer in the windshear. We were vectored around for another approach. The second approach; though definitely challenging and an unfamiliar procedure (we really don't train for this kind of somewhat radical maneuvering under these conditions); was completed successfully with a normal landing. Upon gate arrival; we wrote up the overspeed; and informed maintenance of the write-up via radio. I don't know what we could have done differently in this circumstance; other than to prematurely and preemptively divert to another station. But that certainly would not have been justified before we encountered the windshear.

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Original NASA ASRS Text

Title: Air carrier Captain reports a reactive windshear warning during approach to IAD in VMC with strong gusty winds. A flap overspeed occurs during the escape maneuver followed by a normal landing.

Narrative: As we approached IAD; I was pilot flying as Captain; and IAD ATIS showed ILS 1C approaches in use. But upon contacting Potomac Approach; we were told to expect an ILS 1R approach; circle-to-land 30. Weather was good VFR; but winds were strong and gusty out of the northwest; approximately 320@23G32. We briefed and planned for that approach. As we were on about a 15 mile final; updated winds were about the same; just a little stronger; but did not sound particularly dangerous. We discussed a plan for the approach; and where and when I would perform the necessary alignment maneuvers. Tower told us to maintain 180 KTS until turning base; and to maintain runway centerline until within 3 DME. I was hand-flying the last couple of thousand feet of the approach in anticipation of the large turn maneuver for the landing runway. We flew the ILS approach to just inside 3 DME; and were about to turn to the Runway 30 final when we received a Reactive WINDSHEAR Alert. I initiated a go-around; and just after the throttles moved forward; I began to climb straight ahead. We got a series of fairly quick wind gusts as we began the climb; and the airspeed increased rapidly. I began to reduce power as we were assured of exiting the windshear (the warning had stopped sounding); and I noticed we had a momentary overspeed on the flaps. I had been mindful of the varying airspeed; but mostly concerned about dropping below a safe speed; not expecting as much of an increase as we ended up with. I don't know the exact maximum speed or the time we were at that speed; but it was definitely only a short time and a small overspeed; although I did see a very short message LOAD RELIEF on the flap indicator. I reduced power and began retracting flaps immediately after that; as soon as we were no longer in the windshear. We were vectored around for another approach. The second approach; though definitely challenging and an unfamiliar procedure (we really don't train for this kind of somewhat radical maneuvering under these conditions); was completed successfully with a normal landing. Upon gate arrival; we wrote up the overspeed; and informed maintenance of the write-up via radio. I don't know what we could have done differently in this circumstance; other than to prematurely and preemptively divert to another station. But that certainly would not have been justified before we encountered the windshear.

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.