First look: Inside Boeing's first prototype 777X

Boeing's newest wide-body made its global debut on Sunday at the Dubai Airshow.

The 777X first flew in January 2020, shortly before the COVID-19 pandemic threw the airline and aircraft industries into havoc.

The program, which was originally expected to be delivered to the first customer in 2020, has suffered myriad delays and its first delivery is now expected at the end of 2023. Emirates president Tim Clark has suggested that the airline is anticipating that date to slide further, but Boeing commercial senior vice president Mike Fleming affirmed the 2023 target in Dubai on Sunday.

Still, the appearance in Dubai represented a major stepping stone for the aircraft type. It was the first time it had left the United States, where four prototypes of the 777X have accumulated over 1,700 of flight testing hours, a little less than half the approximately 3,500 flight hours the original 777 and the 787 Dreamliner underwent before receiving FAA certification.

Although there have been numerous reasons for the delays, one appears to be increased regulatory scrutiny following the two 737 MAX crashes that killed a total of 346 people.

"As a result of what happened with the MAX, the regulators are being, just like Boeing is, more reflective on how they approach certification," Fleming said in a press briefing on Sunday. "They're being more reflective on what they do and how they do it."

In person, the plane is massive. Really truly massive.

Boeing plans to make two variants of the 777X. The one flown to Dubai, the 777-9, is the larger one.

Just shy of 252 feet long, the 777-9 is about 10 feet longer than the 777-300 with a slightly wider cabin.

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The wingspan, however, is what really stands out. At a little over 235 feet on the ground — compared to 212 feet on the 777-300ER — the plane would be too wide to fit at most airport gates.

To solve that issue, Boeing designed 12-foot folding wingtips. As the plane lands and taxis to the gate, the pilots set the wing tips to fold up. When it's time to depart, once the aircraft pushes back, the wingtips can be unfolded.

The 777-9 will seat up to 426 passengers in a two-class configuration, though the actual capacity will depend on how airlines decide to lay out the cabin. Boeing says that the 777X will include features developed for the Dreamliner, including lower cabin altitude and higher humidity, larger windows and less noise.

That's not all the 777X borrows from the Dreamliner, though it's probably all the average passenger will notice. The plane also uses the flight deck design of the 787, adopting its modernized screen-heavy avionics suite.

The plane is powered by General Electric's new GE9X engine, which was built specifically for the 777X. The engines, which offer 110,000 pounds of thrust, are nearly as wide as a 737 fuselage.

Inside, the cabin on the 777X in Dubai bears little resemblance to what will be the eventual final form seen by passengers. The interior is lined with tanks, tables, and workstations for flight test engineers.

More: Take a look at the new Alaska Airlines 737 MAX that Boeing is using as a flying laboratory

A bunch of neatly organized black tanks are among the features that draw the eye as one walks aboard the current prototype, N779XW, which was the first of the four prototypes to take to the air.

There are 24 of the barrels, which each hold about 120 gallons — that's 1,000 lbs. of water. According to Matthew England, a flight test engineer on-site at the airshow, the gallons are connected by a fairly sophisticated plumbing system and are used to change the weight balance of the aircraft for various flight tests.

Engineers can move the water to different sections of the aircraft as needed during test flights.

It's impossible to judge the eventual passenger experience on an aircraft that's currently a testbed. But there's no question that the 777X feels massive. It's missing the overhead bins, and there are wide gaps between the handful of passenger seats. But while walking through and sitting in the 3-4-3 economy seats, it felt exceptionally spacious and seems like that will continue to once it enters passenger service — even with a full complement of seats.

Speaking of seats. There were a handful of economy seats interspersed in between the water barrels and engineering workstations. I've seen bare-bones placeholder seats in test aircraft before, but something about these was different. The old-style in-flight entertainment screens and copious padding made them look like they'd been ripped out of a cabin in the mid-2010s.

It turns out that's exactly what happened, according to Shaun Newton, another flight test engineer. Boeing purchased the seats from KLM, which was decommissioning them from an older plane.

The seats primarily serve as placeholders, and occasionally the engineers might strap weights into them to simulate passengers. But the seats are actually specified for real use. When Boeing takes the plane to sites like the Dubai Airshow and needs to bring a complement of staff (in this case, engineers and pilots), the seats can actually be used. Some need to be outfitted with supplemental oxygen in case of a decompression, though, since the entire cabin hasn't been outfitted with overhead masks yet.

Unfortunately for those passengers, the IFE isn't hooked up to anything. They need to bring their own devices loaded up with movies for flights like the 15 hour one from Seattle to Dubai.

The plane will likely need around 1,700 or 1,800 more hours of flight testing before it can be certified, but Boeing has insisted that barring unexpected regulatory hurdles, it's confident that it can begin deliveries in late-2023.

Right now, Boeing has 351 orders and commitments from eight airlines — All Nippon Airways, British Airways, Cathay Pacific, Emirates, Etihad, Lufthansa, Qatar and Singapore. The planemaker has not said who will receive the first delivery — Fleming said that had not been decided yet.