WASHINGTON • The president of the United States has two specially equipped Boeing 747-200s jets that are each known as Air Force One when the president is on board.
Both aircraft went into service in 1990 and have a 30-year lifespan. Earlier this year, Boeing received a US$170 million (S$241 million) contract to design a replacement for the ageing pair of Air Force Ones, according to The Washington Post. The US Defence Department's five-year plan indicates a cost of US$2.9 billion over the next five years for design and development.
President-elect Donald Trump said on Tuesday that the price could be more than US$4 billion when finished, which he regarded as too much.
Mr Trump owns a Boeing 757-200 private jet, which he calls Trump Force One. He bought it in 2010 from Microsoft co-founder Paul Allen.
So what's so special about Air Force One?
Contract received by Boeing earlier this year to design a replacement for the ageing pair of Air Force Ones.
Cost of the US Defence Department's five-year plan over the next five years for design and development.
•It can refuel mid-air, meaning it has unlimited range and does not need refuelling stops, according to the White House.
•Onboard electronics have been hardened to protect against an electromagnetic pulse, for example from a nuclear blast.
•Both planes are equipped with advanced secure communications equipment, allowing the aircraft to function as a mobile command centre in the event of an attack on the US. The president can run the country and a war from the air, like a mobile White House.
•Inside the plane, there is 373 sq m of floor space on three levels, including an extensive suite for the president that features a large office, a toilet and a conference room, the White House says.
•Air Force One also has a medical suite that can function as an operating theatre, and a doctor is permanently on board. The plane's two food galleys can feed 100 people at a time.
•The plane's defence capabilities are secret, but it is reported to be capable of repelling missiles and to have a special electronic defence system that can jam enemy radars.
By contrast, Mr Trump's plane, which seats 43 people, has gold- plated fittings, a movie theatre, a bedroom and a conference room.