Narrative:

Upon taking the runway for takeoff, the preceding aircraft reported windshear at 1300 ft, -10 KTS. The tower controller reported the windshear warning at 1500 ft +/-10 KTS. The controller then started calling microburst over the field, then microburst alert over the runway. The controller never gave a specific location, but always used the word 'over' leading me to believe she was still referring to the windshear at 1500 ft. It was all 1 continuous thought. We briefed a full power takeoff and a slower than normal rotation. Our takeoff weight was 684000 pounds. There were none of the flight manual windshear probability parameters (light rain and the advisory from tower). WX radar was on and nothing significant was indicated. Acceleration was normal with the airspeed increasing smoothly with never any hesitation. Climb out normal up to about 1200 ft. When we encountered turbulence, airspeed jumped up about 20 KTS and then settled back to the bug, never getting below bug -10. At 1500 ft, 1 aircraft generated windshear warning, airspeed +/-10 KTS. Initiated the windshear recovery procedure. Immediately recovered with no loss of altitude on either encounter. I believe the use of the word 'over' and the close and continuous advisories relative the 1500 ft windshear advisory and no specific location (point) led us to believe we were dealing with a windshear at 1500 ft on departure only. Human factors: language usage differences and the tower controller seemed rushed to get information out leading us to believe she was using incorrect phraseology (microburst versus windshear). We don't know for a fact if a microburst alert was actually issued for the airport.

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Original NASA ASRS Text

Title: B747-400 FLC DEPARTS ARPT WITH WINDSHEAR WARNING AND MICROBURST ALERT IN EFFECT.

Narrative: UPON TAKING THE RWY FOR TKOF, THE PRECEDING ACFT RPTED WINDSHEAR AT 1300 FT, -10 KTS. THE TWR CTLR RPTED THE WINDSHEAR WARNING AT 1500 FT +/-10 KTS. THE CTLR THEN STARTED CALLING MICROBURST OVER THE FIELD, THEN MICROBURST ALERT OVER THE RWY. THE CTLR NEVER GAVE A SPECIFIC LOCATION, BUT ALWAYS USED THE WORD 'OVER' LEADING ME TO BELIEVE SHE WAS STILL REFERRING TO THE WINDSHEAR AT 1500 FT. IT WAS ALL 1 CONTINUOUS THOUGHT. WE BRIEFED A FULL PWR TKOF AND A SLOWER THAN NORMAL ROTATION. OUR TKOF WT WAS 684000 LBS. THERE WERE NONE OF THE FLT MANUAL WINDSHEAR PROBABILITY PARAMETERS (LIGHT RAIN AND THE ADVISORY FROM TWR). WX RADAR WAS ON AND NOTHING SIGNIFICANT WAS INDICATED. ACCELERATION WAS NORMAL WITH THE AIRSPD INCREASING SMOOTHLY WITH NEVER ANY HESITATION. CLBOUT NORMAL UP TO ABOUT 1200 FT. WHEN WE ENCOUNTERED TURB, AIRSPD JUMPED UP ABOUT 20 KTS AND THEN SETTLED BACK TO THE BUG, NEVER GETTING BELOW BUG -10. AT 1500 FT, 1 ACFT GENERATED WINDSHEAR WARNING, AIRSPD +/-10 KTS. INITIATED THE WINDSHEAR RECOVERY PROC. IMMEDIATELY RECOVERED WITH NO LOSS OF ALT ON EITHER ENCOUNTER. I BELIEVE THE USE OF THE WORD 'OVER' AND THE CLOSE AND CONTINUOUS ADVISORIES RELATIVE THE 1500 FT WINDSHEAR ADVISORY AND NO SPECIFIC LOCATION (POINT) LED US TO BELIEVE WE WERE DEALING WITH A WINDSHEAR AT 1500 FT ON DEP ONLY. HUMAN FACTORS: LANGUAGE USAGE DIFFERENCES AND THE TWR CTLR SEEMED RUSHED TO GET INFO OUT LEADING US TO BELIEVE SHE WAS USING INCORRECT PHRASEOLOGY (MICROBURST VERSUS WINDSHEAR). WE DON'T KNOW FOR A FACT IF A MICROBURST ALERT WAS ACTUALLY ISSUED FOR THE ARPT.

Data retrieved from NASA's ASRS site as of July 2007 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.