I've had a LiPo flameball in the relative safety of my own home, and all I managed to do was to get out of the kitchen. I might have dared fling it out of the window if I'd been wearing Nomex but it all happened pretty fast. This video is pretty reminiscent of what I experienced. You get a puff of smoke, accompanied by the sound of venting gas, then the chain reaction starts very quickly:
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As for LiPos within electrical items... If I learned one thing during my childhood, it was that confining explosions tended to make them better! Either way, you I suspect that in a noisy aircraft it would all be over before it was possible to do anything much about it.