The ‘’beobachtungsuhr’’ was made for the German Luftwaffe, and it is absolutely stunning. The big size and the simple dial is because it has to be a very clear face to a ‘beobachter’’ in the sky. This is because a pilot can only quickly glance at his watch and needs to be able to tell the time easily. It wasn’t uncommon for a pilot to even wear it on his upperleg.
More onto the dial; an aviation watch has to have an Arabic index and the index has to strongly contrast with the colour of the dial, preferably white on black. Also the case must be unpolished (rather mat finish) so that the light from the sun doesn’t reflect in the eyes of a pilot during the flight.