NYC to Capetown? Frankfurt to Buenos Aires? London to Hong kong? - Nope. The longest (duration) scheduled flights ever were those made by the Australian airline Qantas from Perth to Colombo, Ceylon (now Sri Lanka) starting in 1942. At first the camouflaged PBY flying boats had only three passenger seats and two bunks for the 27+ hour non-stop flight (a number took more than 32 hours), but they later accommodated a few more people. I'm guessing the ringing in the passenger's ears began to subside sometime in the 1960s.
At the beginning of the flight, the passengers were required to stand as far forward as possible, but as fuel was burned off, they were permitted to move aft.
Nothing to do with Buckers of course, but what a fascinating story.
You can read more about this remarkable service in the "Anecdotes" section of this website. It was contributed by retired BA captain and seasonal Aussie Bob Grimstead.
http://www.youtube.com/watch?v=rkiavk3yZOU