A brevity call announcing the launch of an infrared-guided air-to-air missile (e.g., AIM-9 Sidewinder, R-73).
The missile homes on heat signatures and does not require radar illumination after firing.
Application in DCS World
In DCS multiplayer, “Fox 2” warns other pilots to expect IR missile activity and helps prevent misidentification of launch cues. It also alerts friendly aircraft to potential threat reactions in the vicinity.