R5D / US Coast GuardCoast Guard Douglas R5D airplane model. The Coast Guard acquired twenty Douglas R5Ds C 54s. This was the military version of the Civilian DC 4 The Army Air Forces Air Forces designation was C 54. The first five aircraft were acquired in 1950. from the USAF. The additional fifteen were acquired from both the USN and USAF. The R5Ds were used for transport duties, logistical support, search and rescue operations, duty with the International Ice Patrol,