From the earliest days of wireless communication, the Morse code letter R (dit-dah-dit) has been used to indicate 'O.K. -- understood.' So 'Roger' was the logical voice-phone equivalent." Also from “I Hear America Talking” by Stuart Berg Flexner (Von Nostrand Reinhold Co., New York, 1976).“Roger! A code word used by pilots to mean ‘your message received and understood’ in response to radio communications; later it came into general use to mean ‘all right, OK.’ Roger was the radio communications morse code word for the letter R, which in this case represented the word ‘received.’ ‘Roger Wilco’ was the reply to ‘Roger’ from the original transmitter of the radio message, meaning ‘I have received your message that you have received my message and am signing off.” Wilco implies "I will comply" SOURCE: http://www.soksa.com/thread.aspx?lt=1&lp=0&sku=297 P.S. There are words to represent every letter to avoid confusion. If a pilot said "F" or "S" over a staticy radio, it would be hard to understand for sure which he was saying. But if he said "Foxtrot" or "Sierra" there's no danger of misunderstanding. You can't afford to have misunderstandings in a military situation. SEE: http://www.kostis.net/hints/pilots-alphabet.htm