The system uses the ESPNOW protocol which is a wireless communication protocol defined by Espressif.
The WilCo Shutoff system works by having the remote (carried by the pilot) continuously broadcast a message to all currently connected shutoff modules (mounted in the plane).
If a shutoff module does not receive these broadcast messages in a timely manner (it is out of range), the module activates a solenoid valve that shutoff the fuel to the engine. It is also possible to shutdown using the button on the remote to broadcast a “stop” message to all connected shutoff modules.
The shutoff module reports back to the remote, also using ESPNOW, values such as battery voltage, mode, status and MAC address. These values can be displayed via a web server hosted on the remote.