Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 757-200 and -300 series airplanes and Model 767 series airplanes. This proposed AD would require replacing the existing operational software of the Pegasus flight management computer (FMC) system with new, improved operational software. This proposed AD is prompted by reports of "old" or expired air traffic control (ATC) clearance messages being displayed on the control display unit (CDU) of the FMC system during subsequent flights. We are proposing this AD to prevent display of "old" or expired clearance messages on the CDU of subsequent flights, which could result in the airplane entering unauthorized airspace or following a flight path that does not provide minimum separation requirements between aircraft, and a consequent near miss or a mid-air collision.