Recent requirements for incorporation of ground proximity mitigate this risk.

Experts say that the new instrument, called an enhanced ground proximity warning system, has the potential to make those kinds of accidents extremely rare.

The equipment is called an "enhanced ground proximity warning system" and costs $70,000 to $115,000 for each plane.

This was complicated by a ground proximity warning not sounding until immediately before the crash.

The ground proximity warning system is often heard saying, "Too low, terrain!"

The aircraft was not equipped with ground proximity warning system, nor was this required.

An enhanced ground proximity warning system was introduced in 1996, which could have prevented the accident.

Consideration should be given to the development of a ground proximity warning system for helicopters.

Again, helicopters are vulnerable due to their close ground proximity.