Narrative:

As I was departing runway 36 I experienced severe turbulence and a brief loss of control due to windshear. The aircraft experienced uncommanded banks of up to 45 degrees and airspeed fluctuations of +/-5 KTS. Brennard airport (79C) consists of a narrow runway with obstructions on all sides. The runway is runway 18/36 and is paved with dimensions of 2450 ft by 20 ft. On the west side there is a solid line of trees and hangars near the runway. On this day the winds at nearby appleton/outagamie county (atw) were last reported at 280 degrees; 15 KTS gusting to 20 KTS; which would normally exceed the crosswind limitation of my aircraft. However; due to the buildings and trees obstructing the wind flow to the runway at 79C; I noticed the windsock indicating only about a 10 KT crosswind. Even though I had received the appleton metar; I elected to take off with a student and 2 passenger aboard. Takeoff was normal until we reached a ht of 50-100 ft AGL and got above the tree line. At that point the aircraft hit rotors of wind spilling over the buildings. It was climbing but not under my control whatsoever. We experienced violent turbulence and windshear. The stall horn sounded twice but I was able to regain control. Also; the strength of the wind pushed us east toward another area of trees. We diverted to oshkosh (osh) to accomplish a safe landing into the wind.

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Original NASA ASRS Text

Title: C172 PLT ENCOUNTERS SEVERE TURB AND WINDSHEAR DURING TKOF AND CLB WITH MOMENTARY LOSS OF ACFT CTL; DIVERTS TO ANOTHER ARPT.

Narrative: AS I WAS DEPARTING RWY 36 I EXPERIENCED SEVERE TURB AND A BRIEF LOSS OF CTL DUE TO WINDSHEAR. THE ACFT EXPERIENCED UNCOMMANDED BANKS OF UP TO 45 DEGS AND AIRSPD FLUCTUATIONS OF +/-5 KTS. BRENNARD ARPT (79C) CONSISTS OF A NARROW RWY WITH OBSTRUCTIONS ON ALL SIDES. THE RWY IS RWY 18/36 AND IS PAVED WITH DIMENSIONS OF 2450 FT BY 20 FT. ON THE W SIDE THERE IS A SOLID LINE OF TREES AND HANGARS NEAR THE RWY. ON THIS DAY THE WINDS AT NEARBY APPLETON/OUTAGAMIE COUNTY (ATW) WERE LAST RPTED AT 280 DEGS; 15 KTS GUSTING TO 20 KTS; WHICH WOULD NORMALLY EXCEED THE XWIND LIMITATION OF MY ACFT. HOWEVER; DUE TO THE BUILDINGS AND TREES OBSTRUCTING THE WIND FLOW TO THE RWY AT 79C; I NOTICED THE WINDSOCK INDICATING ONLY ABOUT A 10 KT XWIND. EVEN THOUGH I HAD RECEIVED THE APPLETON METAR; I ELECTED TO TAKE OFF WITH A STUDENT AND 2 PAX ABOARD. TKOF WAS NORMAL UNTIL WE REACHED A HT OF 50-100 FT AGL AND GOT ABOVE THE TREE LINE. AT THAT POINT THE ACFT HIT ROTORS OF WIND SPILLING OVER THE BUILDINGS. IT WAS CLBING BUT NOT UNDER MY CTL WHATSOEVER. WE EXPERIENCED VIOLENT TURB AND WINDSHEAR. THE STALL HORN SOUNDED TWICE BUT I WAS ABLE TO REGAIN CTL. ALSO; THE STRENGTH OF THE WIND PUSHED US E TOWARD ANOTHER AREA OF TREES. WE DIVERTED TO OSHKOSH (OSH) TO ACCOMPLISH A SAFE LNDG INTO THE WIND.

Data retrieved from NASA's ASRS site as of January 2009 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.