Final answer:
The Air Force flight cap signifies an officer by the metal rank insignia, which varies from bars to stars, pinned on the cap.
Step-by-step explanation:
On the Air Force flight cap, the significance that the wearer is an officer is indicated by the presence of specific insignia. Officers in the Air Force are distinguished by silver or gold rank insignia. This insignia is typically a metal badge that indicates the officer's rank, such as second lieutenant or major, and is pinned on the flight cap. The rank insignia for officers varies from bars for lower-ranking officers to stars for generals. Enlisted personnel, on the other hand, have different insignia or none at all depending on their rank and position within the Air Force.