Falling through the sound barrier -that's about 690 mph in old money without a safety net.

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I'd like to have a peep at the ElfinSafely risk assessment for this one

I can hear the magical voice of Bob Newhart ringing in my ears describing this - Right so your'e 21 and a bit miles up and you just step out into the icy thin air and go through the sound barrier

And you thought you were in trouble when the -ondom split !