Can military officers change occupation to become pilots?
In the USAF, it has, historically, been common for rated Navigators to be selected for pilot training, and possible, though less common, for young officers in other career tracks as well.

That said, this process is


competitive (so certainly not guaranteed for a particular individual), and
dependent on the "needs of the service", so what is going on "now" may be entirely different from what was going on "then".


Also, the demand for UAV operators may have changed this dynamic considerably; it may be a far different process to become a "drone pilot" from a non-rated field, than to become a "real pilot."  Talking with active duty officers (not recruiters) who are up to date on this landscape is indispensable for getting the most current picture.