Mayday - Fuel - Interessant sak, men Mayday? - Curt Lewis

United flight in mayday call likely had 30 mins fuel left


A United 787 declared an emergency landing at Sydney airport Thursday morning.

A United Airlines Boeing 787 Dreamliner that declared an emergency landing at Sydney Airport Thursday morning would have had 30 minutes fuel left after landing from a 14-hour flight from Los Angeles, according to the pilots' association.

The rare mayday call by an international flight - which briefly shut down operations at the airport and surrounding streets - illustrates one of the complications from sophisticated forecasting systems designed to minimise the cost of carrying fuel.

Flight 839 landed at Kingsford Smith Airport at 8.38am - seven minutes early - without mishap after the pilots told the tower they were running out of a fuel and needed to land immediately, according to aviation officials.

"They would have said 'mayday, mayday, mayday fuel," said Murray Butt, the president of the Australian and International Pilots Association.

The NSW police force cut off streets near the airport in case the 62-metre long plane crash landed. Fire engines and ambulances were waiting on the airport tarmac for the plane to land.

Mayday calls are rare
Aviation officials played down the significance of the incident. "It's a precaution in reality," a spokesman for the Civil Aviation Safety Authority said. "It's a standard international broadcast you are required to make when you enter the reserve fuel."

But mayday calls are rare by any aircraft, let alone a major airline. Captain Butt, a Qantas Airways pilot for 32 years, said he had never issued one.

"A 'mayday' call indicates an aircraft is in grave and imminent danger and requires immediate assistance," the Airservices Australia website says.

A United spokesman in San Fransisco wouldn't confirm an emergency was called or how much fuel was left. "We are continuing to investigate," he said.

A CASA spokesman said several factors could cause aircraft to use more fuel than expected: unexpected headwinds, storms that have to be avoided or a requirement to fly at a lower altitude, where jet engines are less efficient.

Two warnings

International guidelines say passenger aircraft should land with 30 minutes of fuel left. Under standard procedures the United Airlines pilots would have declared "minimum fuel" to air traffic control, which would have let the controllers know they didn't have enough fuel to divert to another airport, Captain Butt said.

When the pilots realised they were going to breach the 30-minute reserve requirement they would have declared the emergency, which allowed them to land on a runway immediately during Sydney Airport's busy morning period, Captain Butt said.

The local police were altered around 6am, about half an hour before the plane landed.

Among the many emergencies that occur in aircraft, almost running out of fuel is relatively uncommon. From 2007 to 2016, only 3 per cent of the 930 accidents and serious incidents in Australian aviation were related to fuel, according to statistics published by the Australian Transport Safety Bureau.

As airlines have become more sophisticated, they have carefully managed the fuel their planes carry. As a result, the amount of fuel available for emergencies has declined, because it is expensive to carry fuel that isn't used.

"They have spent millions on fuel planning systems," Captain Butt said. "They have got it down to a fine art in terms of minutes, not tens of minutes."

Qantas began operating the 787-9, also known as the Dreamliner, from Perth to London in March. The flight takes 17 hours.