In a few hours, Singapore Airlines Flight 22 is scheduled to touch down at Newark Liberty International Airport, after a nearly 18 hour trip from Singapore.

It's the longest scheduled commercial flight in history, on a route that the airline already tried once before--and yet  failed to turn into a stable, profitable route.

So why try it again? And what's it like to be trapped inside a pressurized metal tube flying five miles above the Earth for the equivalent of two and a half workdays? 

Here's the story of the flight, and what it's like to fly on it.

(Update: Flight 22 landed safe and sound at 5:29 a.m., 30 minutes ahead of schedule.)

1. No economy class

Perhaps your first thought on hearing about this flight is how horrible it would be to be stuck in an economy seat for 18 or 19 hours. Singapore Airlines says there are no economy seats; although most of the non-business class cabin is outfitted as "premium economy." It's set up as a 2-4-2 pattern throughout most of the plane.

2. Packed seats

The earlier version of this Singapore Airlines route, a decade ago, used four engine planes, and they weren't efficient enough. The new Airbus A350-900ULR it's using now has only two engines and is goes a lot further on the same fuel. As for demand, the airline said it had only a handful of premium economy tickets left before takeoff.

3. A different environment

Higher ceilings. Vertical sidewalls. Better lighting. And the cabin will feel like it's at 6,000 feet, versus 8,000 in a normal airliner. The humidity is supposed to be kept at 20 percent, basically double what it is on most airplanes.

"You may not exactly pinpoint why it's so comfortable and so nice to be flying on this airplane, but everything was done on purpose," an Airbus official told CNN.

4. Two crews

Pilots need to sleep, too. So there are two pilot/co-pilot teams, which trade off on flying and resting. Interestingly, because of the way they're staggering the shifts, the same pilot and co-pilot who took off will also land the plane.

5. Every contingency

What do you do if somebody dies on the flight? We hate to even think of this, but on a 20-hour flight, the plane comes with a dead body storage locker.

"Cabin crew have been instructed to use the locker in the event of a death on a long-haul flight - particularly if the aircraft is busy, with no free seats on which to lay out the deceased," reports The Guardian.

6. Good timing

Actually, I'm just realizing that all of the hype about this being the world's longest flight that I've been reading about for two days is actually a fib. From Singapore to Newark, the flight will run about 17 hours and 25 minutes; it's the return flight from Newark to Singapore that will likely exceed 19 hours. Culprit: headwinds and tailwinds

7. Lots of media

The departure gate was a well-covered celebration, and there are at least two journalists on board that I know of, live-blogging, tweeting and Instagramming the entire flight.  

Richard Quest of CNN, sitting in business class, reported around 11 p.m. Eastern that the flight was nearing Alaska before heading southwest to Newark. It's a bit after midnight this as I'm wrapping up, less than 20 miles from its destination as it happens.