Narrative:

Departing msp on flight for mdw, thunderstorms were approaching from the west and moving east. We were given runway 22 at msp for departure. Our radar showed the thunderstorm cells were still 75 mi west of the airport. Other aircraft were departing msp on runways 22 and 12L. Just prior to our takeoff clearance, tower reported their sensors were reporting a 20 KT loss of airspeed 2 mi off the approach end of runway 12L. None of the departing aircraft had made any windshear reports. Both the first officer and I felt that, based on our radar and since no one had reported any windshear (except the tower), that we could depart runway 22 with an immediate turn to the east and beat the thunderstorm. Also, thoughts of hail damage to our aircraft if we stayed on the ground crossed my mind (based on previous experience). We departed on runway 22. We experienced moderate to severe turbulence for the next 15-20 mins until we could get far enough away from msp. We ended up flying our own headings based on what the radar was showing us. Finally we encountered smooth air and proceeded to mdw. Looking back, I should have taken the tower's windshear advisory prior to takeoff and treated it the same as I would have a PIREP of the same magnitude. This would have prevented me from departing at all. Also, I should not have been concerned about the possible hail damage my aircraft might sustain if I stayed on the ground. Unfortunately, air carrier does not have a procedure for dealing with strong thunderstorms if you are away from the gate and on a taxiway when a storm approachs.

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Original NASA ASRS Text

Title: FLC OF DC9 IS INFORMED PRIOR TO DEP THAT THERE IS POSSIBLE WINDSHEAR OFF THE END OF THE RWY WITH TSTMS APCHING FROM E AND W. THEY DEPART AND ENCOUNTER SEVERE TURB FOR 15-20 MINS.

Narrative: DEPARTING MSP ON FLT FOR MDW, TSTMS WERE APCHING FROM THE W AND MOVING E. WE WERE GIVEN RWY 22 AT MSP FOR DEP. OUR RADAR SHOWED THE TSTM CELLS WERE STILL 75 MI W OF THE ARPT. OTHER ACFT WERE DEPARTING MSP ON RWYS 22 AND 12L. JUST PRIOR TO OUR TKOF CLRNC, TWR RPTED THEIR SENSORS WERE RPTING A 20 KT LOSS OF AIRSPD 2 MI OFF THE APCH END OF RWY 12L. NONE OF THE DEPARTING ACFT HAD MADE ANY WINDSHEAR RPTS. BOTH THE FO AND I FELT THAT, BASED ON OUR RADAR AND SINCE NO ONE HAD RPTED ANY WINDSHEAR (EXCEPT THE TWR), THAT WE COULD DEPART RWY 22 WITH AN IMMEDIATE TURN TO THE E AND BEAT THE TSTM. ALSO, THOUGHTS OF HAIL DAMAGE TO OUR ACFT IF WE STAYED ON THE GND CROSSED MY MIND (BASED ON PREVIOUS EXPERIENCE). WE DEPARTED ON RWY 22. WE EXPERIENCED MODERATE TO SEVERE TURB FOR THE NEXT 15-20 MINS UNTIL WE COULD GET FAR ENOUGH AWAY FROM MSP. WE ENDED UP FLYING OUR OWN HDGS BASED ON WHAT THE RADAR WAS SHOWING US. FINALLY WE ENCOUNTERED SMOOTH AIR AND PROCEEDED TO MDW. LOOKING BACK, I SHOULD HAVE TAKEN THE TWR'S WINDSHEAR ADVISORY PRIOR TO TKOF AND TREATED IT THE SAME AS I WOULD HAVE A PIREP OF THE SAME MAGNITUDE. THIS WOULD HAVE PREVENTED ME FROM DEPARTING AT ALL. ALSO, I SHOULD NOT HAVE BEEN CONCERNED ABOUT THE POSSIBLE HAIL DAMAGE MY ACFT MIGHT SUSTAIN IF I STAYED ON THE GND. UNFORTUNATELY, ACR DOES NOT HAVE A PROC FOR DEALING WITH STRONG TSTMS IF YOU ARE AWAY FROM THE GATE AND ON A TXWY WHEN A STORM APCHS.

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.