LUMINOX - 3001 DIVE SERIES ORIGINAL, they don't set off the metal detector - these days sadly the most useful aspect of a timepiece on your wrist.
I wouldn't go for a 'aviator' style large watch as its all a bit suspect image-wise whilst you go through your training. If you're not careful you'll find yourself in a pair of Ray-Ban classics toying with the leather flying jacket catalogue... Sometime it takes years to live this sort of thing down.
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