Use in Parachuting
In parachuting, a static line is a cord attached at one end to the aircraft and at the other end to the top of the jumper's 'D-Bag' (Deployment Bag, where the canopy is packed into). The parachutist's fall from the aircraft causes the static line to become taut, this then pulls the D-Bag out of the container on the jumper's back. The static line and D-Bag stay with the aircraft as the student leaves, and is pulled back into the aircraft by their dispatcher. Now, as the student continues to fall, the canopy is allowed to inflate as it is now out and free of its D-Bag. One could think of it as the student dragging the parachute behind them causing the wind rushing upwards to force open and inflate the canopy. Within 4 seconds the canopy should be inflated and supporting the student, as long as no malfunctions have occurred of course. In unlikely event of a malfunction, students are taught how to cut away the main canopy and deploy their reserve chute. The aim of static line progression is to teach students how to maintain a stable body position upon exiting the aircraft and to teach them the motion of deploying their canopy via the pilot chute mechanism.
As mentioned above the parachutist must adopt and maintain a stable body position throughout deployment to minimise the chances of a parachute malfunction. This method of parachute deployment is commonly used in several ways:
- Training student skydivers
- BASE jumping
- Military paratroopers jumping from very low altitudes (400+ feet or 122+ meters)
- Soviet and successor state military standard procedure for all airborne infantry jumps, regardless of altitude
Static line jumping carries risk of injury that, according to one study, doubles when performed in combat.
For training students in civilian operations, modifications to existing static line equipment may be made to simplify operations. One such modification is to attach the deployment bag to the parachute instead of the static line, which also requires some modification to allow the static line to detach, typically a Velcro fastener. This leaves much less material "in the wind" behind the plane after the jumper has left; this isn't a problem for larger cargo aircraft used in military jumping, but presents a major issue for smaller aircraft used in civilian operations. This modification also results in a somewhat slower opening, which softens the opening shock at the cost of altitude, a minor concern for jumpers exiting at 2,800 ft (850 m).
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