Automatic activation device

In skydiving, an automatic activation device (AAD) is a dead man's switch consisting of an electronic-pyrotechnic or mechanical device that automatically activates the opening sequence of the main or reserve parachute container when the AAD is falling below a preset altitude and above a preset descent speed.

These newer models have been proven more reliable as their built-in computers allow for better estimation of altitude and vertical speed.

The device, based on radar principles, opened a main recovery parachute at either of two preset heights (1,000 or 1,700 ft.) above the ground.

The air delivery system consisted of the cargo package, two parachutes (drogue and main), and the radar actuator.

The radar was designed to determine when the cargo reached a preset altitude, generating a firing signal which actuated a mechanism releasing the main parachute at that time.