One of aviation's worst nightmares, a fire on board can have disastrous consequences. And though these epic tragedies have exacted a terrible human cost, they've also helped lead the way towards significantly safer skies. In Manchester, a holiday flight bound for the Mediterranean faces an inferno on the runway. In the skies over Saudi Arabia, a flight ful of pilgrims is consumed by flames. And, after a UPS cargo plane crashes in Dubai, investigators discover a tiny battery with outsize implications.