Multiple deaths and injuries have resulted in recent decades as a result of mid-ar collisions and near-misses involving gliders or sail planes, with commercial jetliners, private planes and corporate aircraft. Pilots typically have only a few seconds to take corrective action, if they see the approaching aircraft.

The leading cause of these mishaps is the absence in the gliders of transponders that alert other aircraft in the immediate vicinity, as well as the Federal Aviation Administration’s air traffic controllers, of a glider’s presence. Many glider pilots voluntarily use transponders, but a significant number do not and some turn the devices off when they enter what they believe to be uncrowded air space.