The primary purpose of the Foxtrot Flag is to indicate:

The primary purpose of the Foxtrot Flag is to indicate that flight operations are underway. When displayed by a vessel, it signals to others that there is air traffic related to the vessel, which could include launching or recovering aircraft. This is important for maintaining safety and awareness in areas where vessels and aircraft are operating in close proximity, as it helps prevent potential collisions or misunderstandings about the operations taking place.

In maritime communication, the Foxtrot Flag is recognized internationally, and its adoption ensures that all vessels are aware of the status of flight operations, allowing them to take necessary precautions while navigating nearby. This functionality is crucial for the effective coordination of activities on and above the water, especially when dealing with military or research vessels that may have specific flight operation protocols.