↑ Wallace, Lane. “Airborne Trailblazer: Two Decades with NASA Langley's 737 Flying Laboratory”. NASA. Truy cập ngày 22 tháng 4 năm 2012. Prior to the 1970s, air transport operations were not considered sufficiently demanding to require advanced equipment like electronic flight displays. The increasing complexity of transport aircraft, the advent of digital systems and the growing air traffic congestion around airports began to change that, however. She added that the average transport aircraft in the mid-1970s had more than 100 cockpit instruments and controls, and the primary flight instruments were already crowded with indicators, crossbars, and symbols. In other words, the growing number of cockpit elements were competing for cockpit space and pilot attention.
