What will a beacon that flashes white twice and then green indicate?

A beacon that flashes white twice followed by green indicates a military airport. The specific combination of colors and patterns used by aviation beacons serves to provide important information regarding the type of facilities and services at the location.

In this case, the two white flashes followed by a green flash are a standardized signal indicating the presence of a military airfield. This is critical for pilots and aircraft operators to identify their surroundings, especially when navigating through areas with various types of air traffic environments. Understanding these signals helps ensure safety and situational awareness in the airspace.

The other options relate to different types of facilities and would use different beacon signals. A civilian airport typically has a different beacon pattern, while an emergency landing zone and an air traffic control facility have their distinct identification signals as well. Recognizing the specific signal associated with military airports is part of essential training and helps aviators navigate accurately and safely.