A truck driver's safe practice should be to release the air from the trailer brakes when the truck is docked. This will automatically apply the mechanical brakes to minimize trailer movement. Once a driver believes it's safe to depart they push the air supply button inside the truck. This action puts the air back into the trailer and releases the brakes. The driver can then put the truck into gear and is free to pull away! In the drivers mind it was not "unscheduled"!

Salvo stops the Unscheduled Truck Departure before it happens.

"The Salvo Process" locks out the trailer’s emergency glad hand fitting and interlocks it with the loading dock door so that if the dock door is open the Salvo glad had lock can’t be removed.

Even if the driver believes its time to depart and pushes the air supply button inside the truck to release the trailer brakes, it doesn't work! The driver is stopped before the truck can pull away.

monroenews.com