What causes the BAK-15 net to release when an aircraft engages?

The BAK-15 net is a type of arrestor system used at certain airfields and aircraft carriers to safely stop aircraft that are landing. The proper functioning and release of this net is primarily achieved through shear link devices.

When an aircraft engages the BAK-15 net, it exerts significant force upon the net. The shear link devices are specifically designed to detect this force and facilitate the release mechanism. These devices are calibrated to "shear" or break upon reaching a predetermined load, ensuring that the net deploys only when a certain level of impact is reached. This is crucial for safely capturing the aircraft without damaging it or the net system.

Other options, such as pressure sensors, magnetic release methods, or hydraulic systems, may play roles in various types of systems or applications. However, in the context of the BAK-15 net's operation, the shear link devices are the key components responsible for its release mechanism, making them the correct choice.