FAA Order 7110.65N "Air Traffic Control"
2-4-20 Aircraft Identification...
"...7. Presidential aircraft and Presidential family aircraft:
(a) When the President is aboard a military aircraft, state the name of the military service, followed by the word "One."
EXAMPLE-
"Air Force One."
"Army One."
"Marine One."
(b) When the President is aboard a civil aircraft, state the words "Executive One."
(c) When a member of the President's family is aboard any aircraft, if the U.S. Secret Service or the White House Staff determines it is necessary, state the words "Executive One Foxtrot." "
-Dave