21.   The concept is already in use commercially in noise-cancelling headphones to wear in passenger aircraft.

22.   The Federal Aviation Administration requires the doors to be locked from the time a passenger aircraft pushes back from the gate until it arrives at the gate upon landing.

23.   The government said it is reconsidering a program to build an indigenous mid-size passenger aircraft, the Financial Times reported.

24.   The National Transportation Safety Board had recommended before the accident that cargo areas in passenger aircraft be outfitted with fire-detection systems.

25.   The other, planned by Airbus Industrie of Europe, would be a completely new design, the first double-decker passenger aircraft from tip to tail.

26.   The panel also endorsed asking airlines to voluntarily install smoke-detection systems in the cargo holds of all passenger aircraft.

27.   The other, planned by Airbus Industrie of Europe, would be a new design, the first double-decker passenger aircraft from tip to tail.

28.   The package was placed aboard an Aeromexico passenger flight to Miami, in violation of rules that forbid transporting hydrazine and other hazardous chemicals on passenger aircraft.

29.   There is enough demand for the charter flights that two of the five planes stay configured as passenger aircraft during the week.

30.   Tilt-rotor passenger aircraft would ferry customers between airports to city centers.