Narrative:

On preflight, discussed windshear precautions use of maximum power. Discussed with deice lead technician not to deice. Aircraft clean, no snow sticking, winds blowing hard. WX radar inoperative, no pws installed. On taxi out, WX worsening, visibility down to 1/2 mi, winds 240 degrees at 24 KTS gusting to 39 KTS. Taxi to runway 22L. During wing check, had hard time getting a clear view of entire wing (dark, blowing snow). Wing appeared clear of any accumulation. Used B737 ahead to confirm our opinion. Takeoff roll normal till 110 KTS. Announced airspeed hang-up. Airspeed jumped ahead. Delayed rotation for windshear. PF rotated, normal liftoff with left drift. Normal positive rate of climb, gear up. I (PNF) noticed over rotation to 2-3 degrees above flight director guidance. Felt PF was correcting, then heard 'I have a problem.' thinking it was a pitch control problem, I pushed forward on the stick with the captain to lower the nose 5 degrees. Slight airframe buffet as nose was pushed over. Checked performance instruments. Greater than V2+20 KTS, 1600 FPM climb, altitude climbing. Continued normal climb out. On review, it appeared we may have had windshear event. However, no cautions or warnings. Supplemental information from acn 573825: on taxi out, the snow increased to near blizzard conditions. Visibility was down to 1800-2000 RVR. After liftoff, I (PF), called gear up, but was struggling with a perceived roll problem from liftoff. I thought maybe I had an engine problem. It went away as I climbed up, but I probably lost the pitch when looking to the engine gauges. As far as we can remember, the wings were level for all this. We were maximum power for takeoff.

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Original NASA ASRS Text

Title: OVER ROTATION FELT BY THE FLT CREW OF A B737-300 AFTER LIFTOFF WITH PF CITING A PROB DURING A WINDSHEAR NIGHT OP DEP PROC AT ORD, IL.

Narrative: ON PREFLT, DISCUSSED WINDSHEAR PRECAUTIONS USE OF MAX PWR. DISCUSSED WITH DEICE LEAD TECHNICIAN NOT TO DEICE. ACFT CLEAN, NO SNOW STICKING, WINDS BLOWING HARD. WX RADAR INOP, NO PWS INSTALLED. ON TAXI OUT, WX WORSENING, VISIBILITY DOWN TO 1/2 MI, WINDS 240 DEGS AT 24 KTS GUSTING TO 39 KTS. TAXI TO RWY 22L. DURING WING CHK, HAD HARD TIME GETTING A CLR VIEW OF ENTIRE WING (DARK, BLOWING SNOW). WING APPEARED CLR OF ANY ACCUMULATION. USED B737 AHEAD TO CONFIRM OUR OPINION. TKOF ROLL NORMAL TILL 110 KTS. ANNOUNCED AIRSPD HANG-UP. AIRSPD JUMPED AHEAD. DELAYED ROTATION FOR WINDSHEAR. PF ROTATED, NORMAL LIFTOFF WITH L DRIFT. NORMAL POSITIVE RATE OF CLB, GEAR UP. I (PNF) NOTICED OVER ROTATION TO 2-3 DEGS ABOVE FLT DIRECTOR GUIDANCE. FELT PF WAS CORRECTING, THEN HEARD 'I HAVE A PROB.' THINKING IT WAS A PITCH CTL PROB, I PUSHED FORWARD ON THE STICK WITH THE CAPT TO LOWER THE NOSE 5 DEGS. SLIGHT AIRFRAME BUFFET AS NOSE WAS PUSHED OVER. CHKED PERFORMANCE INSTS. GREATER THAN V2+20 KTS, 1600 FPM CLB, ALT CLBING. CONTINUED NORMAL CLBOUT. ON REVIEW, IT APPEARED WE MAY HAVE HAD WINDSHEAR EVENT. HOWEVER, NO CAUTIONS OR WARNINGS. SUPPLEMENTAL INFO FROM ACN 573825: ON TAXI OUT, THE SNOW INCREASED TO NEAR BLIZZARD CONDITIONS. VISIBILITY WAS DOWN TO 1800-2000 RVR. AFTER LIFTOFF, I (PF), CALLED GEAR UP, BUT WAS STRUGGLING WITH A PERCEIVED ROLL PROB FROM LIFTOFF. I THOUGHT MAYBE I HAD AN ENG PROB. IT WENT AWAY AS I CLBED UP, BUT I PROBABLY LOST THE PITCH WHEN LOOKING TO THE ENG GAUGES. AS FAR AS WE CAN REMEMBER, THE WINGS WERE LEVEL FOR ALL THIS. WE WERE MAX PWR FOR TKOF.

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.