CYPRES is an acronym for Cybernetic Parachute Release System. It refers to a specific make and model of an automatic activation device (AAD), a device that automatically opens a parachute (typically as a reserve system for a skydiver) under certain circumstances. A CYPRES will usually open at a preset altitude if the rate of descent is over a certain threshold. The manufacturer of the CYPRES is Airtec.
The CYPRES works by using a cutter to cut the reserve container closing loop. A spring-loaded pilot chute then leaves the container and breaks through the skydiver's slipstream to begin reserve deployment.[1]
The CYPRES comes in four different models: Expert, Student, Tandem and Speed. The basic operation of the units is the same; only the activation parameters are different, having been optimized for different types of skydiving.