At 17-plus hours, this Qatar Airways flight from New Zealand is the world's longest

Qatar Airways has launched its first service to Auckland, New Zealand with the return leg set to be the longest scheduled commercial flight by flying time.

Flight QR920 departed Doha's Hamed International Airport and arrived in Auckland on Monday at 7:15am local time, about 15 minutes early.

The Boeing 777 flight took 15 hours and 50 minutes, passing over 10 time zones, five countries and travelling 14,535 kilometres before reaching Auckland.

But even that flying time may be looked on jealously by passengers on the return flight which, due to high-altitude winds, was expected to take 17 hours and 30 minutes, according to the company website.

This would make it the world’s longest passenger service in terms of flying time, according to tracking website flightradar24.

Improvements in technology over the last decade have allowed more efficient fuel use, encouraging longer flights.