Narrative:

After about a 3 hour 40 min delay on the ground (due to a continuous series of thunderstorms) our flight was cleared for takeoff on runway 24R. After we taxied into position, we noticed on radar a solid line of cumulo nimbus beginning directly overhead and extending roughly 60 mi off the departure end of runway 24R. Moderate with occasional heavy rain was falling on the airport and the wind sock indicated frequent changes in both direction and velocity of wind. After about a min or 2 of flight time we told departure control we needed a left turn followed by frequent deviations to avoid strong cells. The captain was flying and we were both operating the radar and making frequent visual references outside. During the course of WX avoidance, we encountered 2 episodes of strong downdrafts. The first downdraft (or wind shear) was of significant duration -- approximately 10 seconds. The sinking sensation immediately got our attention and we both must have been looking outside to see what we were encountering. Upon scanning back in at the radar and flight instruments, I noticed our airspeed was approaching 300 KTS (at approximately 6000 ft). Immediately we noticed an updraft followed by another downdraft. It was at this time that center queried us about our airspeed. In the next few seconds, I keyed the microphone 2 times to make a response but was interrupted both times by the captain who was telling me what explanation he wanted made. I guess when the controller heard the keying of the microphone and no transmission made, he must have thought we didn't know how to respond. So he said, 'never mind, I don't want to know! Just get it back to 250 KTS!' the captain went ahead and made the explanation and requested further deviations because a slowing of airspeed would have required an inordinately high pitch attitude and would have placed us squarely in the middle of a strong cell. After deviations were granted, we achieved better separation from the WX and were able to regain control over airspeed. The remainder of the climb and flight were normal. Looking back on it, I suppose one could say that one pilot should be monitoring flight instruments at all times so that if a deviation occurs, he can advise the PF immediately. But in the case of severe WX avoidance, a combination of radar operation and outside visual reference sometimes requires the efforts of both pilots in order to insure safety of flight. We appreciate the apparent understanding of ATC in this instance.

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Original NASA ASRS Text

Title: TEMPORARY LOSS OF ACFT CTL AND AIRSPD DEVS ARE EXPERIENCED BY LGT ACR FLC IN DEP PROC FROM ARPT SURROUNDED BY TSTM ACTIVITY.

Narrative: AFTER ABOUT A 3 HR 40 MIN DELAY ON THE GND (DUE TO A CONTINUOUS SERIES OF TSTMS) OUR FLT WAS CLRED FOR TKOF ON RWY 24R. AFTER WE TAXIED INTO POS, WE NOTICED ON RADAR A SOLID LINE OF CUMULO NIMBUS BEGINNING DIRECTLY OVERHEAD AND EXTENDING ROUGHLY 60 MI OFF THE DEP END OF RWY 24R. MODERATE WITH OCCASIONAL HVY RAIN WAS FALLING ON THE ARPT AND THE WIND SOCK INDICATED FREQUENT CHANGES IN BOTH DIRECTION AND VELOCITY OF WIND. AFTER ABOUT A MIN OR 2 OF FLT TIME WE TOLD DEP CTL WE NEEDED A L TURN FOLLOWED BY FREQUENT DEVS TO AVOID STRONG CELLS. THE CAPT WAS FLYING AND WE WERE BOTH OPERATING THE RADAR AND MAKING FREQUENT VISUAL REFS OUTSIDE. DURING THE COURSE OF WX AVOIDANCE, WE ENCOUNTERED 2 EPISODES OF STRONG DOWNDRAFTS. THE FIRST DOWNDRAFT (OR WIND SHEAR) WAS OF SIGNIFICANT DURATION -- APPROX 10 SECONDS. THE SINKING SENSATION IMMEDIATELY GOT OUR ATTN AND WE BOTH MUST HAVE BEEN LOOKING OUTSIDE TO SEE WHAT WE WERE ENCOUNTERING. UPON SCANNING BACK IN AT THE RADAR AND FLT INSTS, I NOTICED OUR AIRSPD WAS APCHING 300 KTS (AT APPROX 6000 FT). IMMEDIATELY WE NOTICED AN UPDRAFT FOLLOWED BY ANOTHER DOWNDRAFT. IT WAS AT THIS TIME THAT CTR QUERIED US ABOUT OUR AIRSPD. IN THE NEXT FEW SECONDS, I KEYED THE MICROPHONE 2 TIMES TO MAKE A RESPONSE BUT WAS INTERRUPTED BOTH TIMES BY THE CAPT WHO WAS TELLING ME WHAT EXPLANATION HE WANTED MADE. I GUESS WHEN THE CTLR HEARD THE KEYING OF THE MICROPHONE AND NO XMISSION MADE, HE MUST HAVE THOUGHT WE DIDN'T KNOW HOW TO RESPOND. SO HE SAID, 'NEVER MIND, I DON'T WANT TO KNOW! JUST GET IT BACK TO 250 KTS!' THE CAPT WENT AHEAD AND MADE THE EXPLANATION AND REQUESTED FURTHER DEVS BECAUSE A SLOWING OF AIRSPD WOULD HAVE REQUIRED AN INORDINATELY HIGH PITCH ATTITUDE AND WOULD HAVE PLACED US SQUARELY IN THE MIDDLE OF A STRONG CELL. AFTER DEVS WERE GRANTED, WE ACHIEVED BETTER SEPARATION FROM THE WX AND WERE ABLE TO REGAIN CTL OVER AIRSPD. THE REMAINDER OF THE CLB AND FLT WERE NORMAL. LOOKING BACK ON IT, I SUPPOSE ONE COULD SAY THAT ONE PLT SHOULD BE MONITORING FLT INSTS AT ALL TIMES SO THAT IF A DEV OCCURS, HE CAN ADVISE THE PF IMMEDIATELY. BUT IN THE CASE OF SEVERE WX AVOIDANCE, A COMBINATION OF RADAR OP AND OUTSIDE VISUAL REF SOMETIMES REQUIRES THE EFFORTS OF BOTH PLTS IN ORDER TO INSURE SAFETY OF FLT. WE APPRECIATE THE APPARENT UNDERSTANDING OF ATC IN THIS INSTANCE.

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.