United Airlines Plane Issued 'Mayday' Call Because It Was Running out of Fuel

United Airlines
United Airlines planes sit on the tarmac at San Francisco International Airport on April 18, in San Francisco, California. A spokesperson for United Airlines said one plane suffered a "mechanical issue" this week. Justin Sullivan/Getty Images

A United Airlines flight from Los Angeles to Sydney landed safely on Thursday after low fuel reserves triggered a precautionary measure that set off a mayday call.

Emergency warnings are automatically sent if reserves run low, but the plane had plenty of fuel remaining to land, said a spokesperson for aviation authority Airservices Australia. UA839 landed at Sydney Airport at approximately 6:30 a.m., and no passengers were injured.

According to The Sydney Morning Herald, the Boeing 787 was carrying 180 passengers and 14 crew members. A spokesperson for United Airlines said the plane experienced a "mechanical issue."

"Flight 839 from Los Angeles to Sydney landed safely in Sydney following a mechanical issue," United's statement read. "The aircraft taxied to the gate, and all customers disembarked normally." But on the ground, law enforcement reacted swiftly to the alert, sending teams to the scene.

A New South Wales police statement, published today, said: "A full emergency response [wa s] activated at Sydney Airport this morning after a pilot reported a problem.

"Officers from Botany Bay Police Area Command were alerted to the pilot's concerns shortly after 6 a.m.The traffic control plan was activated at 6.36 a.m., with some major roads surrounding the airport being closed as a precaution. The plane landed safely without incident and the roads reopened at 6.39 a.m."

News.com.au, citing an Airservices Australia spokeswoman, reported the plane had been placed in a holding pattern due to heavy rain in Sydney at the time. An airport representative said there were no further delays as a result of the emergency and that the airport remained operational.

'Fuel Mayday'

Peter Gibson, spokesman for the Australian Civil Aviation Safety Authority, told the Australian Associated Press that strong headwinds across the Pacific may have burned the fuel reserves.

"There's an international standard that requires that, once you get down to your fuel reserve in a flight, you have to declare what is called a 'fuel mayday,'" Gibson told AAP.

"What that tells air traffic control and aircraft in the area is that you need priority to come in," he said. "It doesn't mean you're running out of fuel; you've still got plenty of fuel left, but it's a precaution to say: 'I'm down to my reserve and I need to come in as quickly as can be arranged.'"

Indeed, according to the BBC, the plane would have had enough fuel to last at least 45 minutes.

Passengers on the flight were given no indication that anything was wrong during the landing, according to a reporter from Australia's 9News outlet who was on the plane. "Not a hint, not a mention of any impending doom or mayday situation," journalist Liz Hayes said.

"I did think, 'Gee, that's a lot of flashing lights out there' when we landed, but no more than the flashing lights from emergency vehicles I'd seen in Denver and Washington during this trip, where there was absolutely nothing happening," Hayes said.

A second passenger who was onboard flight 839, identified as Ian Lambert, said: "Everyone was calm, there was no panic, there was no announcement."

Airservices Australia said a full mayday call "indicates an aircraft is in grave and imminent danger and requires immediate assistance. Controllers immediately alert ARFF services if available, as well as local emergency services, with details on the incident to enable them to respond appropriately and provide information and assistance to pilots."

United Airlines
United Airlines planes sit on the tarmac at San Francisco International Airport on April 18, 2018 in San Francisco, California. Justin Sullivan/Getty Images