Which is a longest flight in the world?
Longest scheduled passenger flight in history is Singapore SQ21/22 between New York (Newark) and Singapore with distance 8285nm by A340-500, the service was dropped in 2013, but Singapore airline planned to reintroduce the route using A350.
Longest non-scheduled passenger flight record is archived by a B777-200LR on 9 November 2005, from Hong Kong to London eastwardly, travelled 11664nm.
Longest fueled Flight endurance record is archived by Robert Timm and John Cook from 4th December 1958 to 7th February 1959, using Cessna 172. And the longest longest Non-refueled record is archived by Dick Rutan and Jeana Yeager from 14th to 23rd December 1986, using Rutan Voyager.