But now Air Force One -- like many other American institutions once considered sacred -- is getting the Donald Trump treatment.

- A name, not a plane -

Technically Air Force One is the callsign for whichever US Air Force plane, no matter how small, is carrying the US president.

But most people identify it with the two heavily modified versions of the Boeing 747-200 jet liner that usually shuttle the US president around the world.

The two current models, called the VC-25A in military speak, both entered service in 1990 during the presidency of George H.W. Bush.

With its classic blue and white livery the current jumbo jet has become so famous that it even spawned a Hollywood thriller named after it, starring Harrison Ford.

Sometimes presidents use smaller planes based on Boeing 757s for shorter flights, dubbed "Baby Air Force One."

- Presidential suite -

"Big Air Force One" boasts luxury features fit for a commander-in-chief.

The president himself has a large suite that includes an office with leather chairs and a polished wooden desk -- a space Trump used for a press conference to sign a proclamation renaming the Gulf of Mexico as the Gulf of America.

A medical suite on board can also function as an operating room, should the worst happen.

There are special cabins for senior advisors, Secret Service members and 13 traveling press. It has two galleys that can feed 100 people at a time, all on specially branded crockery.

- Special features -

But the plane's main role is keeping the US president safe.

Inflight refueling capability means it can stay in the air almost indefinitely.

A hardened electronics system protects against electromagnetic pulses -- whether from nuclear explosions or hostile jammers -- "allowing the aircraft to function as a mobile command center in the event of an attack on the United States," the White House said.

Those communications also keep Trump constantly in touch with the ground -- and able to send social media posts in mid-air.

The jet also has top secret air defenses, according to aviation specialists.

These reportedly include countermeasures that can jam enemy radars and infrared tracking systems, plus dispensers for chaff -- metal shavings that distract radar-guided missiles -- and flares that blind heat-seeking missiles.

- Historic roles -

Inevitably, Air Force One has also played its role in history.

The first specially-designed jets were brought in by John F. Kennedy in 1962, using modified Boeing 707s. One of those jets brought Kennedy's body back to Washington after his assassination in Dallas in 1963.

Then in 2001, George W. Bush took to the skies aboard Air Force One after the 9/11 attacks on New York and Washington.

- Trump obsession -

But Trump has long had something of an obsession with the presidential jets.

The Republican has consistently sought to upgrade them, agreeing a deal with Boeing in 2018 during his first term for two new models based on the newer 747-8 jet.

He also dreamed up a new color scheme -- replacing the one largely in place since Kennedy's time -- with a deep red stripe down the middle of the aircraft and a dark blue underbelly.

Trump likes the new look so much that he still has a model of it on his coffee table in the Oval Office, and showed it off at his inauguration for a second term.

But now he has repeatedly complained about delays and cost overruns.

"We're very disappointed that it's taking Boeing so long... We have an Air Force one that's 40 years old," Trump said on Monday.

"You look at some of the Arab countries and the planes they have parked alongside of the United States of America plane, it's like from a different planet."

One of those same Arab countries, Qatar, has now offered the United States a Boeing 747-8 from the royal family to use as a stopgap Air Force One.

But with ethical concerns and security worries about using a plane from a foreign power for such an ultra-sensitive purpose, it's unclear whether the scheme will ever leave the ground.

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