There's a long history of presidential aircraft, starting with Franklin Roosevelt, but for those long-distance treks, the president currently flies aboard a specially-modified Boeing 747-200B that ...

Only a few of the greatest purchasers of the Boeing 747 were US airlines, and some still have them in service.

Another rare visitor was spotted at Prestwick Airport this week - one of only 16 of its kind left flying across the world.

It's a Boeing 747-200B and comes equipped with a self-contained baggage loader and the ability to re-fuel in flight.