Narrative:

I was flying pilot and captain was acting PIC. We used nexrad and aircraft radar to discover that on the other side of the state was a system of storms. This caused us to make a northern course change approved by ATC.we saw out our windscreen a cloud that did not appear on any of our weather detection screens; we determined that we would ask for a 30 degree deviation around the northern side of this cloud; which was approved; we were about 20-30 miles in front of this cloud.once the turn was completed; our airspeed went from about .77 to .81 as the aircraft began to shake. I brought the thrust levers to idle as the airspeed continued to increase. I transferred controls to the PIC; as the aircraft began to descend uncontrollably and at its worst the airspeed increased to about .83/4 and descent rate was roughly 7;000 ft/min. Immediately after transferring controls; I informed center that we had encountered extreme clear air turbulence and was in an uncontrolled descent. During this time we also encountered an uncontrolled yaw/turn movement as well. ATC responded asking if we would be able to level at 37;000 and I told them negative and would level as soon as we were able; which ended up being 33;000 feet.once the aircraft was under control we contacted maintenance to better understand if we should continue and made the decision to do so. Over wisconsin we began to have small system failures one after the other including rudder boost; yaw dampener; and autopilot; we ran the QRH for all the affiliated cas messages and made the decision to continue with the flight.the flight was completed upon our landing in our filed destination.we did everything we could with the time we had to correct all deviations within the aircraft including course; altitude; and airspeed. We were in VMC conditions and advised ATC of our actions and reasons why. There was no way we could have prevented this situation with the tools we had at our disposal.

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Original NASA ASRS Text

Title: A Learjet 70 flight crew described the entry and recovery from an extreme clear air turbulence encounter which damaged the aircraft while losing 7;000 FT and exceeding Mach .83.

Narrative: I was flying pilot and Captain was acting PIC. We used NEXRAD and Aircraft Radar to discover that on the other side of the state was a system of storms. This caused us to make a northern course change approved by ATC.We saw out our windscreen a cloud that did not appear on any of our weather detection screens; we determined that we would ask for a 30 degree deviation around the northern side of this cloud; which was approved; we were about 20-30 miles in front of this cloud.Once the turn was completed; our airspeed went from about .77 to .81 as the aircraft began to shake. I brought the thrust levers to idle as the airspeed continued to increase. I transferred controls to the PIC; as the aircraft began to descend uncontrollably and at its worst the airspeed increased to about .83/4 and descent rate was roughly 7;000 ft/min. Immediately after transferring controls; I informed Center that we had encountered extreme clear air turbulence and was in an uncontrolled descent. During this time we also encountered an uncontrolled yaw/turn movement as well. ATC responded asking if we would be able to level at 37;000 and I told them negative and would level as soon as we were able; which ended up being 33;000 feet.Once the aircraft was under control we contacted maintenance to better understand if we should continue and made the decision to do so. Over Wisconsin we began to have small system failures one after the other including Rudder boost; yaw dampener; and autopilot; we ran the QRH for all the affiliated CAS messages and made the decision to continue with the flight.The flight was completed upon our landing in our filed destination.We did everything we could with the time we had to correct all deviations within the aircraft including course; altitude; and airspeed. We were in VMC conditions and advised ATC of our actions and reasons why. There was no way we could have prevented this situation with the tools we had at our disposal.

Data retrieved from NASA's ASRS site 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.