I flew on the longest flight in the world, which lasts nearly 18 hours and covers 10,000 miles. Here's what it's like.

• Singapore Airlines relaunched the longest flight in the world on Thursday, connecting Newark Liberty International Airport with its home base at Changi Airport in Singapore.
• Singapore had operated the route — which covers about 10,000 miles and can last up to 19 hours — until 2013.
• Singapore's fleet of new Airbus A350-900ULR jets will be used to operate the route.
• The planes are equipped with business-class and premium-economy cabins only.
• Business Insider had the chance to fly on the launch flight of SQ21 from Newark to Singapore.

Singapore Airlines on Thursday relaunched its nonstop service connecting Newark Liberty International Airport just outside New York City with its home base at Changi Airport in Singapore. At about 10,000 miles with a duration of up to 19 hours, the flight is the longest in the world.

Singapore Airlines Flight SQ22, with a new Airbus A350-900ULR, took off from Changi Airport late Thursday evening local time. Nearly 18 hours later, at 5:30 a.m. ET on Friday, the flight arrived in Newark. Later that morning, Flight SQ21 would make the first nonstop return flight back to Singapore in half a decade.

Flight SQ22 marked the first nonstop flight between the Lion City and the Big Apple since 2013, when Singapore Airlines pulled the plug on the service. At the time Singapore used Airbus A340-500s on the route.

While it has exceptional range and capability, the A340-500 was a relic of the 1990s, and the thirst of its four engines proved too uneconomical to sustain. Even a shift to an all-business-class layout couldn't generate enough income to save the route. So in 2013, the airline canceled the service and returned the A340-500 fleet to Airbus.

Fast-forward five years, and things are quite different. Singapore is the proud owner of a fleet of new Airbus A350-900ULR jets — ULR stands for ultra-long-range — representing the latest in commercial aviation.

The carbon-composite A350's pair of massive Rolls-Royce Trent XWB turbofan engines team up with the plane's sleek wing design to deliver a 25% reduction in fuel consumption over the aircraft it replaced, the company says. In ULR specs, Airbus managed to fit an extra 6,300 gallons of fuel into the A350's tanks, pushing the range up to more than 11,000 miles.

Business Insider purchased a business-class ticket aboard the flight from Newark to Singapore. Here's how it went.

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Singapore Airlines Flight SQ21 to Singapore operates out of Terminal B at Newark Liberty International Airport. Since this was an inaugural flight and there were some additional festivities involved, we arrived more than four hours before the 10:45 a.m. departure time.

After the media briefing, the photo shoots, and the press conference, it was time to get on the plane.

As we waited to board, we caught a glimpse of our chariot, the new Airbus A350-900ULR.