The world's longest commercial flight has left Singapore for New York, beginning a journey scheduled to cover more than 15,000km in almost 19 hours. Singapore Airlines is relaunching the service five years after it was cut because it had become too expensive. Flight SQ22 departed at 15:37GMT with 150 passengers and 17 crew.

The inaugural flight from Changi International Airport to Newark Liberty International airport, which services New York and New Jersey, took off amid much fanfare. However, Singapore Airlines told passengers before take off that their flight to Newark, while still the world's longest flight by distance, could only take some 17 hours. Qantas launched a 17-hour non-stop service from Perth to London earlier this year, while Qatar runs a 17.5-hour service between Auckland and Doha.

Do people want to fly for 19 hours?

The brand new Airbus plane that SIA is using has been configured to seat 161 passengers in all - 67 business passengers and 94 premium economy passengers.

The thinking behind that is that they are selling a premium product - it's for the top end of town," says aviation expert Geoffrey Thomas, who was booked on to Thursday's flight. This is a route between two massive financial hubs, and so they will fill this plane up with business people, or well-heeled travellers who want the convenience of a non stop flight. It's also been proven that when carriers introduce a new non-stop route, the traffic on that route increases threefold.

Qantas meanwhile is in advanced discussions with Airbus and Boeing over an aircraft capable of making a 20-hour flight between London and Sydney. The Australian national flag carrier also plans to fly non-stop from Australia to North America - slightly shorter than the London-Sydney non-stop flight.

Is this the future of long-haul travel?

The A350-900 ULR (ultra-long-range) that set off on Thursday from Singapore to Newark belongs to Airbus' family of long-range, twin-engine aircraft.

The planes have been designed to replace Boeing's older 777 series and use between 20% and 30% less fuel than the 777s did - which is a good thing amid rising oil prices.

Singapore Airlines launched the same non-stop route between Changi and Newark in 2004, but by 2013 the carrier was forced to cancel it. The A340-500 it was using at the time used a lot of fuel and eventually the route became too expensive to run.

Several carriers already use the newer A350-900s on their long-haul routes. They have higher ceilings, larger windows and lighting designed to reduce jetlag - all good things for busy business travellers.

But the ultra-long-range version that SIA has bought from Airbus has the longest capability of any aircraft flying today, thanks in part to a slightly modified fuel system.

It can fly for 20 hours non-stop, which most aviation experts will tell you is the future of very long-haul travel for business and pleasure.