Interceptors wont upgrade

[nestorius]

Playing Germany it is 1945 and I have researched Turbojet interceptors but my advanced interceptors wont upgrade I have kept them on an airfield in home territory just to make sure(in fact one squadron is in Berlin) Doesnt seem to do anything though.

 

[Gaute65]

You'll need to research Rocket Interceptors first. You can find these under the secret weapons tab.

 

[nestorius]

thanks a lot strange though that it says that turbojets make advanced obsolete but doesnt say anywhere I need the rocket ones.