In the context of aviation and aerospace, "Air to Ground" (A/G) refers to communications or systems that involve transmitting information or signals from an aircraft in the air to a ground-based station or receiver. This can include various types of communication, navigation, or data transmission systems.

Examples of Air to Ground systems and applications include:

1. Communication systems: Radio communication between aircraft and air traffic control (ATC) or other ground stations, such as voice communication, data link communications, or emergency locator transmitters (ELTs).
2. Navigation systems: Signals transmitted from aircraft to ground stations, such as GPS or radar systems, to provide location and navigation information.
3. Data link systems: Transmission of data, such as weather information, flight plans, or aircraft performance data, from aircraft to ground stations or vice versa.
4. Surveillance systems: Radar or other sensors that track aircraft positions and velocities, transmitting data to ground stations for air traffic control or other purposes.
5. Automatic Dependent Surveillance-Broadcast (ADS-B): A system where aircraft transmit their position, velocity, and other data to ground stations, which then use this information to track the aircraft and provide separation and guidance.

The Air to Ground connection is critical for safe and efficient aviation operations, enabling communication, navigation, and surveillance between aircraft and ground-based systems.