Narrative:

I was working local control; at the end of an hour that had already experienced four wind shifts due to thunderstorms in the vicinity; outflow boundaries and an impending frontal passage. When a C560 was about 15 miles out; I called TRACON on the shoutline to relay current winds and altimeter (29.92); since the winds had shifted and altimeter was about .15' lower than on the previous ATIS. The C560 was vectored onto the ILS 16 approach. When the pilot called on initially; he inquired about the winds for the circle-to-land 34; a common procedure due to our proximity to a class B airport. I told him the winds off the saws (stand alone weather station); which at the time were approximately 11012g28 and cleared him to land on runway 16. I was not talking to any other aircraft. The field had recently gone VFR; with a thin low-level stratus layer breaking up. We had not updated the ATIS because it was after XA46Z at this point; and the hourly was pending. I observed an east/west oriented; sloping mass of clouds to the north of the field; moving to the south. Initially; due to the diffuse lighting conditions (high cloud layer above); it was difficult to tell whether this was a fog or stratus layer; and how far away or how thick it was. As it moved closer during the event sequence; it became clear that the clouds delineated a frontal boundary moving south; toward the airport. The C560 was behind the frontal boundary; in IMC. When the C560 was on about a 2.5-mile final; shortly after he received the landing clearance; the pilot said; 'we just got a wind shear alert; we're going around.' my first reaction was to treat this as a missed approach; not as a wind shear escape maneuver; even though we had been given a face-to-face briefing on how to handle the latter about one month ago. Our standard missed approach is to climb to 1;400; then a climbing turn to 2;000 (the MVA in the vicinity of the airport) and a turn to a heading of 030. I issued the climb to 1;400; then immediately corrected myself since the C560 was above that altitude; giving him the climb to 2;000 and turn left heading 030. I called TRACON to inform them of the missed approach. The controller gave me a heading of 040; which I relayed to the pilot; who requested higher. Since I was still on the shout line; I asked TRACON; who approved 2;500. The pilot questioned the 040 heading; saying 'looks like we're in the clear just now; 040 heading is going to put us back in the weather.' during this sequence; while coordinating with TRACON; I obtained visual contact with the aircraft in the climbing left turn in front of and apparently slightly above; the cloud mass/frontal boundary. I instructed the C560 to contact approach. Recommendation; the pilot said he had encountered wind shear; but did not explicitly say that he was performing a 'wind shear escape maneuver;' so I should have queried the pilot on whether he was able to accept our standard missed approach; or else to ask him to 'say intentions' prior to issuing any control instructions.

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Original NASA ASRS Text

Title: Tower Controller described a wind shear initiated go around by an air carrier on final that was unable to maintain the ATC assigned altitude; the reporter realizing later that altitude assignments were contrary to recently briefed procedures.

Narrative: I was working Local Control; at the end of an hour that had already experienced four wind shifts due to thunderstorms in the vicinity; outflow boundaries and an impending frontal passage. When a C560 was about 15 miles out; I called TRACON on the shoutline to relay current winds and altimeter (29.92); since the winds had shifted and altimeter was about .15' lower than on the previous ATIS. The C560 was vectored onto the ILS 16 approach. When the pilot called on initially; he inquired about the winds for the circle-to-land 34; a common procedure due to our proximity to a Class B airport. I told him the winds off the SAWS (Stand Alone Weather Station); which at the time were approximately 11012G28 and cleared him to land on Runway 16. I was not talking to any other aircraft. The field had recently gone VFR; with a thin low-level stratus layer breaking up. We had not updated the ATIS because it was after XA46Z at this point; and the hourly was pending. I observed an east/west oriented; sloping mass of clouds to the north of the field; moving to the south. Initially; due to the diffuse lighting conditions (high cloud layer above); it was difficult to tell whether this was a fog or stratus layer; and how far away or how thick it was. As it moved closer during the event sequence; it became clear that the clouds delineated a frontal boundary moving south; toward the airport. The C560 was behind the frontal boundary; in IMC. When the C560 was on about a 2.5-mile final; shortly after he received the landing clearance; the pilot said; 'we just got a wind shear alert; we're going around.' My first reaction was to treat this as a missed approach; not as a wind shear escape maneuver; even though we had been given a face-to-face briefing on how to handle the latter about one month ago. Our standard missed approach is to climb to 1;400; then a climbing turn to 2;000 (the MVA in the vicinity of the airport) and a turn to a heading of 030. I issued the climb to 1;400; then immediately corrected myself since the C560 was above that altitude; giving him the climb to 2;000 and turn left heading 030. I called TRACON to inform them of the missed approach. The Controller gave me a heading of 040; which I relayed to the pilot; who requested higher. Since I was still on the shout line; I asked TRACON; who approved 2;500. The pilot questioned the 040 heading; saying 'looks like we're in the clear just now; 040 heading is going to put us back in the weather.' During this sequence; while coordinating with TRACON; I obtained visual contact with the aircraft in the climbing left turn in front of and apparently slightly above; the cloud mass/frontal boundary. I instructed the C560 to contact Approach. Recommendation; the pilot said he had encountered wind shear; but did not explicitly say that he was performing a 'wind shear escape maneuver;' so I should have queried the pilot on whether he was able to accept our standard missed approach; or else to ask him to 'say intentions' prior to issuing any control instructions.

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.