GPWS was mentioned in the report. Ground Proximity Warning Systems were mandated by most civil aviation authorities in the 1970s. They are designed to alert the crew when a number of standard profiles are encountered, such as a high rate of descent near terrain. Early systems were perceived as unreliable and sometimes deactivated by flight crews by pulling their circuit breakers. Current technology is reliable, and flight crew training focuses on obeying the warnings and executing escape maneuvers.