Narrative:

Just after liftoff at approximately 400 feet; we received a wind shear warning. We were climbing out closely behind another aircraft. The weather had no indication of wind shear whatsoever. No ATIS indication; no aircraft in front or behind us indicating a change in airspeed; no gusty winds. Absolutely nothing. I had rotated slowly as we were following the jet ahead and as I rolled the aircraft off the runway; I probably slightly under-rotated. Given my airspeed and V2; I increased pitch. It was as the airspeed returned to approximately V2+10 we received the warning. I actually saw no indication external to the aircraft of a stagnation. I put the pitch of the aircraft in the flight director bars and monitored both thrust; airspeed and climb. I had called for speed mode/heading mode and actually didn't realize immediately the pitch mode to GA and roll mode. I looked up and thought the first officer had chosen the wrong thing. I asked for navigation and speed. We were tracking the departure; which we continued normally. Departure told us to delete the speed on the departure but before that would have been effective they gave us; (and the aircraft ahead of us; and the aircraft behind us for that matter) a direct turn to 180 degrees instead of the normal departure. We continued the climb out and enroute.I do not think this was actually a wind shear event. There was no stagnation evident; there was no weather to indicate it either before or after; and there was no demonstrable performance decrease. What I think this was a result of the trend toward V2+10 and maybe some wake from the aircraft ahead (which we didn't even feel).

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Original NASA ASRS Text

Title: A Regional Jet flight crew reported receiving a windshear warning on takeoff from ATL that may have been related to the preceding aircraft's wake.

Narrative: Just after liftoff at approximately 400 feet; we received a Wind Shear Warning. We were climbing out closely behind another aircraft. The weather had no indication of wind shear whatsoever. NO ATIS indication; NO aircraft in front or behind us indicating a change in airspeed; NO gusty winds. ABSOLUTELY NOTHING. I had rotated slowly as we were following the jet ahead and as I rolled the aircraft off the runway; I probably slightly under-rotated. Given my airspeed and V2; I increased pitch. It was as the airspeed returned to approximately V2+10 we received the warning. I actually saw NO indication external to the aircraft of a stagnation. I put the pitch of the aircraft in the flight director bars and monitored both thrust; airspeed and climb. I had called for speed mode/heading mode and actually didn't realize immediately the pitch mode to GA and ROLL mode. I looked up and thought the First Officer had chosen the wrong thing. I asked for NAV and Speed. We were tracking the departure; which we continued normally. Departure told us to delete the speed on the departure but before that would have been effective they gave us; (and the aircraft ahead of us; and the aircraft behind us for that matter) a direct turn to 180 degrees instead of the normal departure. We continued the climb out and enroute.I do not think this was actually a wind shear event. There was no stagnation evident; there was no weather to indicate it either before or after; and there was no demonstrable performance decrease. What I think this was a result of the trend toward V2+10 and maybe some wake from the aircraft ahead (which we didn't even feel).

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.