Narrative:

I was the first officer on a flight from st. Louis, mo, to louisville, ky, with a scheduled departure time of XA15 local. At departure time, there were scattered storms moving through the area. We were holding short of runway 12R at intersection M, when the tower controller told us that the wind was now from 330 degrees at 16 KTS and issued taxi instructions for us to use runway 30L instead of 12R. At this time the captain told me to tell ATC that we could still accept a takeoff at runway 12R at intersection M. At this time I promptly told the captain that we 'could not' accept this because we have a 10 KT tailwind component limitation on the mdt and the winds were from 330 degrees at 16 KTS. At this time the captain told ATC that we 'could' accept the takeoff and ATC issued us a 'position and hold' on runway 12R at intersection M, and then a takeoff clearance with a turn to 180 degrees. Once again, I told the captain that we could not accept this takeoff and he completely ignored me and started the takeoff roll. I felt that it was more dangerous to wrestle with the captain over control of the aircraft, so I allowed the takeoff to continue. The takeoff was normal and we switched to departure and were assigned a climb to 5000 ft. While on a heading of 180 degrees and level at 5000 ft, we entered an area of strong wind shear and severe turbulence. We were unable to maintain our altitude of 5000 ft due to the severe downdrafts. The aircraft descended to 4200 ft. The loss of altitude was totally unavoidable, the airspeed was decaying at a rapid rate and the aircraft would not maintain altitude without stalling. So the captain did the only thing he could do and that was to lower the pitch attitude to increase airspeed and the aircraft descended to 4200 ft.

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Original NASA ASRS Text

Title: MDT HAS ALT EXCURSION DUE STRONG WIND SHEAR, SEVERE TURB AND SEVERE DOWNDRAFTS.

Narrative: I WAS THE FO ON A FLT FROM ST. LOUIS, MO, TO LOUISVILLE, KY, WITH A SCHEDULED DEP TIME OF XA15 LCL. AT DEP TIME, THERE WERE SCATTERED STORMS MOVING THROUGH THE AREA. WE WERE HOLDING SHORT OF RWY 12R AT INTXN M, WHEN THE TWR CTLR TOLD US THAT THE WIND WAS NOW FROM 330 DEGS AT 16 KTS AND ISSUED TAXI INSTRUCTIONS FOR US TO USE RWY 30L INSTEAD OF 12R. AT THIS TIME THE CAPT TOLD ME TO TELL ATC THAT WE COULD STILL ACCEPT A TKOF AT RWY 12R AT INTXN M. AT THIS TIME I PROMPTLY TOLD THE CAPT THAT WE 'COULD NOT' ACCEPT THIS BECAUSE WE HAVE A 10 KT TAILWIND COMPONENT LIMITATION ON THE MDT AND THE WINDS WERE FROM 330 DEGS AT 16 KTS. AT THIS TIME THE CAPT TOLD ATC THAT WE 'COULD' ACCEPT THE TKOF AND ATC ISSUED US A 'POS AND HOLD' ON RWY 12R AT INTXN M, AND THEN A TKOF CLRNC WITH A TURN TO 180 DEGS. ONCE AGAIN, I TOLD THE CAPT THAT WE COULD NOT ACCEPT THIS TKOF AND HE COMPLETELY IGNORED ME AND STARTED THE TKOF ROLL. I FELT THAT IT WAS MORE DANGEROUS TO WRESTLE WITH THE CAPT OVER CTL OF THE ACFT, SO I ALLOWED THE TKOF TO CONTINUE. THE TKOF WAS NORMAL AND WE SWITCHED TO DEP AND WERE ASSIGNED A CLB TO 5000 FT. WHILE ON A HDG OF 180 DEGS AND LEVEL AT 5000 FT, WE ENTERED AN AREA OF STRONG WIND SHEAR AND SEVERE TURB. WE WERE UNABLE TO MAINTAIN OUR ALT OF 5000 FT DUE TO THE SEVERE DOWNDRAFTS. THE ACFT DSNDED TO 4200 FT. THE LOSS OF ALT WAS TOTALLY UNAVOIDABLE, THE AIRSPD WAS DECAYING AT A RAPID RATE AND THE ACFT WOULD NOT MAINTAIN ALT WITHOUT STALLING. SO THE CAPT DID THE ONLY THING HE COULD DO AND THAT WAS TO LOWER THE PITCH ATTITUDE TO INCREASE AIRSPD AND THE ACFT DSNDED TO 4200 FT.

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.