Fighter Escort Doctrine event doesn't work

[unmerged(147887)]

I'm trying to get the Fighter Escort Doctrine event to work. I've gone into the console and typed "event 8001" and the pop-up box shows and says the doctrine is available. But when I go into the technology section, it is not available to be researched. Is there another tech that needs to be researched in order for it to work? I'm playing as USA and I'm in mid-1943.

 

[Hagar]

Either 1937 Interceptor combined with (the non-researchable) Semi-Industrial Economy, or Short Notice Response, Dedicated Bomber Protection or Air Reserve. So as the US you need to research either of the latter three.

 

[unmerged(147887)]

Excellent - thank you.