Qantas has set a new record for the longest non-stop commercial flight - but it might not be a green light for the service to go ahead.
The 19-hour test flight from New York to Sydney had 50 passengers and crew on board and they were monitored to see how a long flight affects the human body.
Aviation analyst Irene King told Mike Hosking there are limitations to what the crew can handle.
"What we're dealing with here is the fatigue of the crew and in particular the pilots. That's going to be a major constraint if that's not resolved."
The lengthy flight time also spells legislative issue.
King says current regulations are only up to 17 hour flights.
"Once they get up to 19 hours in a flight time, there is no regulatory framework. That's the problem, they're having to set it"