Thanks for your post. There are still issues with air carriers. The devs are looking into it but up to now they haven't found what's causing this behavior. GO's are treating air carrier tickets fast and they have the power to put your planes on the carrier again.
Another explanation is that your patrol was put outside of their range. Please note that a whole stack's range is limited by the minimum range. So if you have one interceptor that's not upgraded yet in a stack with high level planes you'll be stuck in that ints smaller range.
