Originally Posted by Old King Coal
it's a very foolish thing to try and out-climb a thunderstorm.
Even if there is no cloud above a Cb, that should not be taken to infer that the air above the Cb is free from severe turbulence, and all that climbing would do is put one even closer into coffin-corner, at a time when (if sever turbulence occurs) one needs as much airspeed margin as possible.
To illustrate this, on 10 May 1970 an SR-71 from Kadena was lost when trying to out-climb a thunderstorm. It had just come off a tanker and was returning to operational altitude in afterburner climb. Upon penetration the turbulence caused engine flame-out and the vehicle broke up. Both crewmembers ejected safely.
While different from Cb activity, a 1966 CAT accident illustrates all a/c (regardless of type) can encounter structural and control limits in flight. BOAC flt. 911 (a 707-436) flew into a mountain rotor near Mt. Fuji and broke up in flight. A U.S. Navy A-4 was sent to search for wreckage and flew into the same turbulence. The A-4 went out of control and nearly crashed. Its peak-reading g-meter was pegged at +9 and -4 g, and the plane was grounded for repairs.