depends on the care and maintenance of the watch. my 1941 and 1943 both keep good time but depending on setting. (inside is a regulator switch marked F and S to make the working faster or slower) I wind mine up every morning ( usually about 20 turns of the crown) and set the time to my iPhone internet time... they may lose or gain a minute within 24 hours or so which is normal for an old analog type of watch. (which may be why they were always hacking and syncing watches at briefing before a mission) not sure how often I should get them cleaned and oiled but so far mine keep good time . I don't rely on them to be 100% accurate for but a day at a time since they need to be wound daily anyway.. they are more just worn as fashion.
when my watch was gaining a minute or two per day I gently pushed this lever a bit to slow it down and now it keeps near perfect time... just an arbitrary judgment on how much to set it but it worked for me.
my 1942 Waltham keeps time to ten seconds fast per day. Which is well within AAF specs of within 30 seconds per day. You can't expect more than that for these watches really as they are utilitarian watches and not luxury timepieces.
Pilots only were issued A-11. Ground crews got the Ordnance watches.
Echo that!
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