jahenders
Banned
As noted, there were some around WWI. However, to get any significant number serving openly you'd have to wait until WWII.
Then, ultimately, you have two challenges:
1) Demand -- as long as there are enough men to do it, there's little push to have women do it.
2) Limits on combat -- the US, and others, had provisos against women in Combat and most of the roles discussed were considered combat and the men doing them were considered to be 'in combat.'
West:
So, in the West, your best bet would probably be some slight expansion of the ferrying role to include some long (mostly boring) patrol flights. At first, those might be unarmed spotting/reconaisance. If they have some where they see potential targets (U-boats recharging, etc), perhaps there's some lobbying to give them some weapons. However, again, there's a problem that men fulfilling the same role are considered to be 'in combat' so how could they not be? Perhaps there's a nuance based on their starting and ending base.
If that works, perhaps homeland interceptor is a possibility, but that role was often used as training for deploying forward, so I don't think the USAAF would want women (who they wouldn't send forward) doing it.
If things somehow progress to a point where they're really considering women in true combat roles, perhaps you have the Lady Airmen serving alongside the Tuskegee Airmen -- two groups of non-standard pilots.
Russia:
Russia could be a very distinct possibility, but there just weren't many women with the assumed flying, engineering, and/or political background to get into the field.
Then, ultimately, you have two challenges:
1) Demand -- as long as there are enough men to do it, there's little push to have women do it.
2) Limits on combat -- the US, and others, had provisos against women in Combat and most of the roles discussed were considered combat and the men doing them were considered to be 'in combat.'
West:
So, in the West, your best bet would probably be some slight expansion of the ferrying role to include some long (mostly boring) patrol flights. At first, those might be unarmed spotting/reconaisance. If they have some where they see potential targets (U-boats recharging, etc), perhaps there's some lobbying to give them some weapons. However, again, there's a problem that men fulfilling the same role are considered to be 'in combat' so how could they not be? Perhaps there's a nuance based on their starting and ending base.
If that works, perhaps homeland interceptor is a possibility, but that role was often used as training for deploying forward, so I don't think the USAAF would want women (who they wouldn't send forward) doing it.
If things somehow progress to a point where they're really considering women in true combat roles, perhaps you have the Lady Airmen serving alongside the Tuskegee Airmen -- two groups of non-standard pilots.
Russia:
Russia could be a very distinct possibility, but there just weren't many women with the assumed flying, engineering, and/or political background to get into the field.
In World War II women made up a large amount of training and ferry pilots, helping to free up men for combat roles. By the 1950s there was serious consideration of using women in national space programs, as it was thought that their physiology was more suitable. A major consideration for the early space program would simply be the smaller size of women, as they weigh less than men and do not need as much space or supplies.
Given this, could women have been allowed to fly in combat units earlier than they were historically, especially outside of communist countries? Could they have served in defensive roles piloting interceptors?