A long-range Qantas flight had to make an unscheduled stop to refuel this week.

The flight from Dallas, USA to Brisbane was delayed by about two hours because of a fuel stopover in the Pacific island of New Caledonia. The route is the longest Boeing 747 route in the world and experts say it pushes the limits of the jumbo-jet’s range.

From Brisbane to Dallas, the flight is just over 15 hours in duration; however the return leg is nearly an hour longer due to strong headwinds, particularly at this time of year. Now the carrier has come under scrutiny and may be forced to adjust the route.

Airbus A380 pilot Captain Barry Jackson of the Australian and International Pilots Association accused Qantas of using the improper jet for the extensive route, adding that Boeing’s long range 777 wide-body jet would be much more suitable. He said if service via the Boeing 747 continues on the route that there would likely be several more diversions and added that a 777 would use half the fuel in the same range.

The airline has since responded that it was closely monitoring performance on the newly introduced route in the effort of gaining ‘operational experience’; however added that it was still too early to make any changes or conclusions regarding the aircraft.