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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 decent speed.
AADs are typically used to open the reserve parachute container at a preset altitude if the descent rate exceeds a preset activation speed. [1] This indicates that the user has not opened their 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 newer style electronic-pyrotechnic models. These newer models have been proven more reliable as their built-in computers allow for better estimation of altitude and vertical speed. Electronic AADs typically employ a small pyrotechnic charge to sever the reserve container closing loop, allowing the spring-loaded reserve pilot chute to deploy.
Examples of specific AADs are:
Manufacturer | Models | Technology |
---|---|---|
Advanced Aerospace Designs | Vigil, Vigil 2 | Electronic |
Airtec | CYPRES, CYPRES 2 | Electronic |
Aviacom | Argus | Electronic |
FXC | Astra | Electronic |
MarS | MPAAD, M2 | Electronic |
FXC | Model 12000 | Mechanical |
Hi Tek | Model 8000 | Mechanical |
SSE | Sentinel [2] | Mechanical |
2MPZ | KAP-3 | Mechanical |
AADs can malfunction and deploy the reserve parachute when the firing parameters have not been met. This will result in either a premature reserve deployment if it happens prior to main deployment, or in both parachutes being deployed if it happens after main deployment. A premature reserve deployment can be dangerous if it happens while exiting the aircraft, in close proximity to other skydivers in freefall, or if the skydiver is falling faster than the safe deployment speed, which can result in catastrophic equipment failure and injury or even death of the jumper. A deployment of both canopies could result in an entanglement between the two canopies.
Undesired AAD activations can also occur due to user error. This can happen if the skydiver deploys the main canopy too low, and the AAD activates while the main is deploying, resulting in both parachutes being deployed. It can also happen if the AAD is not calibrated to the correct ground level, either due to turning the AAD on at a location with a different elevation than the airport, or entering an incorrect altitude offset (a feature that is normally used to compensate for a landing zone that is at a different elevation than the airport).
Some models of AAD carry a risk of deploying the reserve inside the aircraft in cases of sudden aircraft depressurization, or during a rapid descent when landing with the aircraft.
The risk of an AAD malfunction is far smaller than the risk of a situation in which the AAD can save somebody's life. [3] For this reason, many countries (such as Denmark) [4] require AADs for all skydivers and jumps. In countries where AADs are not legally mandated (such as the US), many drop zones still require all jumpers to use AADs. Others require all student jumpers to use them even if licensed jumpers are not. [5]
AADs were originally called AODs for Automatic Opening Device, but was changed to Automatic Activation Device, AAD, in the 1980's to reflect the true nature of its operation. The AAD activates the opening sequence, but other very uncommon events could prevent the activation sequence from fully opening the parachute. [6]
High-Altitude Delayed-Opening Parachute Actuating Device, also called HADOPAD, was a radar actuator used as a component in a delayed opening aerial-delivery system. The system was developed by the Harry Diamond Laboratories in the mid-1960s, which later became a part of Army Research Laboratory. 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. [7]
BASE jumping is the recreational sport of jumping from fixed objects, using a parachute to descend to the ground. BASE is an acronym that stands for four categories of fixed objects from which one can jump: buildings, antennas, spans (bridges) and earth (cliffs). Participants jump from a fixed object such as a cliff and after an optional freefall delay deploy a parachute to slow their descent and land. A popular form of BASE jumping is wingsuit BASE jumping.
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag or, in a ram-air parachute, aerodynamic lift. A major application is to support people, for recreation or as a safety device for aviators, who can exit from an aircraft at height and descend safely to earth.
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Bill Booth is an American engineer, inventor, and entrepreneur in the skydiving equipment manufacturing industry. His invention of the 3-ring release safety device has enhanced skydiving safety. He founded the companies United Parachute Technologies and Complete Parachute Solutions, which had 150 employees as of 2015.
A slider is a small rectangular piece of fabric with a grommet near each corner used to control the deployment of a "ram-air" parachute. Also called a "reefing device." A ram-air parachute has a tendency to open very rapidly. At high velocities, the opening shock from a rapid deployment can cause damage to the canopy or injury to the jumper. The slider was developed as a way of mitigating this. During deployment, the slider slides down from the canopy to the risers. Air resistance slows its descent. The slider holds the lines together, which slows the parachute inflation. The slider also deflects some of the rising air column away from the center of the canopy as it inflates. This also helps moderate the speed of opening. This invention solved the rapid deployment problem with ram-air designs. Sliders also reduce the chance of the lines twisting to cause a malfunction.
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A reserve static line, occasionally called a Stevens Lanyard or Stevens Release, is a device that automatically opens the reserve parachute container when the main parachute is cut-away. The RSL is a lanyard connecting one or both of the main parachute risers to the reserve ripcord.
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