Could it be possible to activate the rescue without any dedicated switch, for instance throughout the sticks behavior and position. for instance in certain module, the simple fact to get the hands off TX while flying is interpreted in no time by the module as a signal to trigger the rescue (I guess no moves on the slicks and both prof, ail, tail are centered is easy to reckon).
Should this be possible, it would be very convenient and reliable to rescue the model : Just hands up (instead of searching this f... switch in less than a flash
