Out of curiosity, was the SAFE mode active in the instructor's transmitter too at the time of the crash? Was the Apprentice flown in safe mode at any time during that flight prior to the loop and subsequent loss of control when switching to SAFE mode? If that was the first time the SAFE was activated during that flight, then perhaps it is possible the receiver did not properly initialize when it was powered up. For SAFE to work properly, the receiver needs to learn which way is up every time it is powered up. The plane needs to be completely motionless (no bumping, moving or tilting it) during initialization. Did the airplane controls go through two complete sets of control twitches while linking to the transmitter? If it did not, then I suspect the receiver may not have "learned" which way is up and subsequently tried to fly the plane into its incorrectly assumed "up" position when the SAFE switch was selected. Lets see if Andy Kunz (with Spektrum) replies with a more probable explanation.