Automatic activation device
Automatic Activation Device in skydiving terminology refers to an electronic-pyrotechnic or mechanical device that automatically opens the main or reserve parachute container at a preset altitude or after a preset time.
AADs are typically used to open the reserve parachute container at 750 ft (230 m) if the user's descent rate exceeds the preset activation speed. [1]This indicates that the user has not opened his parachute, or that the parachute is malfunctioning and is not slowing the descent rate sufficiently.
The older style mechanical AADs are falling out of fashion in favour of the newer style electronic-pyrotechnic models. The built-in computers in the newer models can make much better estimates of the altitude and the vertical speed, therefore making the units more reliable than the older types.
Examples
Examples of specific makes of AADs are:
Electronic
- Argus
- Astra
- Cypres / Cypres 2
- MPAAD
- Vigil
These types of AAD typically employ a small pyrotechnic charge to sever the reserve container closing loop, allowing the spring-loaded reserve pilot chute to deploy.
Mechanical
- FXC 12000
- Hi Tek 8000
- KAP-3
- SSE Sentinel[2]
Safety
AADs can malfunction and deploy the reserve chute after the main is open, but this is rare even with the older mechanical AADs and almost unheard of with newer electronic models. Skydivers experiencing such malfunctions can potentially have 2 parachutes out at the same time if the AAD activates while the main canopy has not been cleared.
AAD malfunctions resulting in premature reserve deployments or in both chutes deploying can also occur with some models when the AAD is not recalibrated to the new altitude after changing drop zones. There is also a risk with some models of the AAD deploying the reserve inside the aircraft in cases of sudden loss of altitude or having to cancel the skydive and return to earth in the aircraft. The other main cause of AAD malfunction is people forgetting to turn them on. All of these potential problems can be avoided by reading and following the instruction manual.
The risk of an AAD malfunction is far smaller than the risk of a situation in which the AAD can save somebody's life. Many drop zones require all jumpers to use AADs, and most require student jumpers to use them.
External links
- Argus - Argus SIS
- Airtec - Cypres and Cypres 2
- FXC Corporation - FXC 12000 and Astra
- Advanced Aerospace Designs - Vigil
- ParachuteHistory.com - Hi Tek 8000
- ParachuteHistory.com - Sentinel