The long-delayed Air Force One is one of the most expensive, complex planes in the world. Here's what makes the presidential plane unique.

In his first term, Trump showed off his design for the plane's colors to ABC News. At his inaugural ball, he cut a cake adorned with a model of the presidential jet.

At the time, Trump's press secretary said he was touring the plane to check out new hardware and tech, adding that the tour would help highlight "the project's failure to deliver a new Air Force One on time as promised."

The 747 Trump toured was owned by the Qatari government. Its tail number, P4-HBJ, features the initials of the country's former prime minister and one of its wealthiest royals, Hamad bin Jassim bin Jaber Al Thani.

Its interior is more lavish than Air Force One, with an entertainment room, double beds, and en-suite bathrooms.

Yves Pickardt, the project lead from the Parisian design house Alberto Pinto, told Altitudes Magazine in 2018: "Such a project is a dream come true that happens only once or twice in a designer's lifetime. In a way, this is a landmark in aviation history."

"The president wants the airplane sooner, and so we're working with Elon and the team to figure what can we do to pull up the schedule of that aircraft," Ortberg told CNBC.

It may look like a Boeing 747, but it is actually a militarized version of the commercial jet called a VC-25A. The next version is known as the VC-25B.

Air Force One officially refers to any plane transporting the president. Sometimes, the president has flown on a Boeing C-32 — a military version of the 757 — that is more typically used as Air Force Two.

The next presidential jet is based on an even larger 747-8, which has a 224-foot wingspan and is 250 feet long. Its enormous size has even contributed to production delays.

In 2022, The Wall Street Journal reported that one difficulty during production included trying to shift one of the VC-25Bs onto jacks — but the weight "significantly exceeded" how much they were designed to hold.

Two empty mini bottles of tequila were also found on board one of the planes that year, sparking an investigation, per the Journal.

After US airspace was shut down in the wake of the 9/11 attacks, President George W. Bush and his staff spent eight hours on Air Force One.

Air Force One has around 238 miles of wiring — twice that of a typical 747 — which is shielded to protect from an EMP.

Electronic countermeasure defense systems located at the top of the plane can also jam enemy radars.

These can be used to confuse heat-seeking missiles. There are also some defense capabilities that remain classified.

Air Force One can also refuel in midair — but that won't be a feature on the next version, seemingly due to financial constraints.

The lower entrance has retractable stairs, which are convenient if rolling staircases aren't available upon landing or due to security concerns.

As NPR reported, President Joe Biden more frequently used the shorter stairs after tripping on a stage in June 2023.

As the plane transports VIPs, throughout much of the project, Boeing needed workers with high-level security clearance, adding to the complexity of building the aircraft.

In 2023, Pentagon officials were looking into why staff without such credentials were working on the jet — with the lapse involving some 250 workers, The Wall Street Journal reported.

Earlier this month, an official confirmed to The New York Times that security requirements had been reduced for some staff, after the newspaper reported Musk had been pushing for the change.

As well as a pilot and co-pilot, there is a a flight engineer and a navigator.

Flight engineers used to be common on airliners until technology developments in the early 1980s.

Their uniforms have "Air Force One" embroidered above the presidential seal.

The VC-25A has two galleys that can provide 100 meals in one sitting.

In 2018, Axios reported that Trump wants Air Force One to have a bigger bed. A 2021 National Geographic documentary said the designs included a larger TV, more seating, and a queen bed.

President George W. Bush told Runner's World in 2002 that he had a treadmill added to his room on the jet.

Opposite the desk is a large couch that wraps around the wall.

On the other side of this room, there's a TV that can be used for teleconferencing.

The interiors of the new plane have also been a source of delays.

In 2021, Boeing filed a lawsuit against GDC Technics, a supplier for the new Air Force One, alleging it was roughly a year behind schedule in completing interior work.

GDC then filed a countersuit alleging the delays were due to Boeing's mismanagement and that payments were overdue.

The supplier then filed for Chapter 11 bankruptcy — before the two sides reached a settlement six months later.

In the middle of this picture, you can see a beige phone and a white phone. The former is a secure line, while the latter is for unclassified use.

This is the only part of Air Force One that resembles a typical airliner's layout, albeit with leather seats.

However, some passengers have taken their own souvenirs. Last year, the White House Correspondents' Association warned journalists to stop stealing items from the Air Force One.

The BBC reported that pillowcases, glasses, and gold-rimmed plates are among the things said to have vanished from Air Force One.

It's also unclear what color the plane's livery will be.

The Air Force has said Trump's preferred blue, red, and white would add to delays because the dark blue would necessitate further tests due to added heat in some environments.

Biden then chose a light-blue color similar to previous presidential jets — but Trump has continued to champion his original design.