President-elect Donald Trump has once again proved he doesn’t mind making the big calls on social media, tweeting plans to cancel the order for an Air Force One upgrade.

The presidential jets – there are two of them – were ordered by Ronald Reagan and introduced during George H W Bush’s reign in the early 1990s.

But a planned upgrade of the 25-year-old 747s has been thrown into doubt after Mr Trump claimed the project’s “out of control” costs had topped $US4 billion ($5.3 billion).

“Cancel order!” he posted on Tuesday (US time). Mr Tump has his own plane – a Boeing 757 – which is bedecked in white leather and gold. (Take a tour of it at the bottom of this story.)

Boeing is building a brand new 747 Air Force One for future presidents, but costs are out of control, more than $4 billion. Cancel order!

— Donald J. Trump (@realDonaldTrump) December 6, 2016

Speaking to media after the tweet, Mr Trump accused aeronautics giant Boeing of essentially ripping off the US government.

“I think Boeing is doing a little bit of a number,” he said.

“We want Boeing to make a lot of money, but not that much money.”

Following the comments, $US1 billion was wiped off the Boeing share price, before it quickly recovered.

Since the European Aeronautic Defence and Space Company (now Airbus Group) dropped out of a US government tender in 2009, Boeing was the only possible provider of the planes, removing competition for price.

Hours after Mr Trump’s comments, Boeing sought to quell speculation about the deal with a statement on its website.

“We look forward to working with the U.S. Air Force on subsequent phases of the program allowing us to deliver the best planes for the president at the best value for the American taxpayer,” it read.

The gym, the TVs, the M&Ms

The Obama-signed M&Ms found on Air Force One. Photo: Twitter

“People sometimes ask me what the biggest perk of being President is,” Mr Obama told White House visitors in 2015.

“No.1 is the plane.”

Despite its popular usage, Air Force One is not actually the name of the presidential plane – it is the call sign used for any aircraft carrying a serving US president.

And since 1990, all US presidents have flown on one of the dual Boeing VC-255s.

Boeing stopped making its 747-200 series decades ago, and any replacement part now needs to be custom-made at an exorbitant cost, while flying costs have been estimated at about $A242,000 per hour.

But don’t let the age of the planes fool you – flying on Air Force One is exponentially more comfortable than your average Jetstar flight.

President Obama takes a call in the ‘Oval Office in the Air’. Photo: Getty

Each of the identical Boeings comprises 370 square metres of space, with the president’s personal space demarcated with patriotic, star-covered carpet.

The plane holds 87 phones, 19 televisions and an onboard gym – presumably only accessible once the seatbelt sign has been turned off.

Large, leather-bound chairs adorn the conference rooms and president’s private office, as do mostly beige interiors, designed by Nancy Reagan herself.

Flourishes – like the special edition presidential M&Ms (pictured above) – aside, impenetrable security is the most important feature of Air Force One.

The aircraft is designed to withstand a nuclear attack, with 383 metres of heavily protected wiring that can withstand electromagnetic pulses.

After the 9/11 terror attacks, when then-President George W Bush was forced to land for an emergency live address, it was decided the president should be able to address the nation while onboard the plane.

It carries flares designed to ward off heat-seeking missiles and can fly 9700 kilometres – one-third of the way around the world – without needing to refuel.

But given the aircraft have clocked well over a million hours of flying time, Mr Trump might have to reconsider his cancellation plans.

Watch a tour of Air Force One below:

Take a tour of Trump’s 757: