Larger cargo airlines tend to use new or recently built aircraft to carry their freight. However, many still utilize older aircraft, including those no longer suited for passenger service, like the Boeing 707, Boeing 727, Douglas DC-8, DC-10, MD-11, Airbus A300, and the Ilyushin Il-76. Examples of the 60-year-old Douglas DC-3 are still flying around the world carrying cargo (as well as passengers). Short range turboprop airliners such as the An-12, An-26, Fokker Friendship, and British Aerospace ATP are being modified to accept standard air freight pallets to extend their working lives. This normally involves the replacement of glazed windows with opaque panels, the strengthening of the cabin floor and insertion of a broad top-hinged door in one side of the fuselage.
The An-225, world's largest aircraft, also used by Antonov Airlines, a Ukrainian cargo airline
Cargo airlines (or airfreight carriers, and derivatives of these names) are airlines mainly dedicated to the transport of cargo by air. Some cargo airlines are divisions or subsidiaries of larger passenger airlines.
Tower: "Delta 351, you have traffic at 10 o'clock, 6 miles."
Delta 351: "Give us another hint! We have digital watches."