Douglas DC-4 C-54M

The C-54M is a specialised modification of the C-54 to carry coal during the Berlin Airlift. 38 conversions were made. Carrying bulk coal in a transport aircraft is no small thing: the dust gets everywhere and attacks cables and controls, which is why a dedicated version was needed rather than improvising on the standard aircraft.

More than 300 C-54s and R5Ds formed the backbone of the US contribution to the Berlin Airlift in 1948, and they were the main airlift again during the Korean War. After Korea the C-54 was replaced by the Douglas C-124 Globemaster II, but the Air Force kept using it until 1972; the last active Navy Skymaster — a C-54Q of the Naval Test Pilot School at NAS Patuxent River — was retired on 2 April 1974.