Again, Marine One may not necessarily be a helicopter. The way
the system works is that if the US president is on the aircraft,
it's callsign number is One, and the number is preceded by the
service: Air Force, Navy, Marine, Army or Executive (if the
aircraft is civilian).
Therefore, bismarck, your conclusion is not quite correct. For
example, the S3 that Bush flew had the callsign Navy One.
