(CNN)Australia's busiest airport was on high alert Thursday after a United Airlines flight from Los Angeles issued a mayday call due to low fuel reserves.
Police said they activated a "full emergency response" after the pilot of flight UA839 reported a problem around 6 a.m. local time. Some major roads around the airport were briefly closed "as a precaution" as the plane made its final approach.
In a statement, United said the flight experienced a "mechanical issue," adding that it "taxied to the gate and all customers disembarked normally."
Airservices Australia, the nation's navigation authority, said the pilot issued a mandatory mayday call due to low fuel levels as the flight completed its 15-hour trip from LAX.
"A fuel mayday triggers emergency procedures," a spokeswoman said. "This was a precautionary procedure and at no time were the passengers at risk."
According to the International Federation of Air Line Pilots' Associations, per global aviation rules pilots must declare a fuel emergency with the signal "MAYDAY, MAYDAY, MAYDAY, FUEL," if reserves are at a level where they will have to make a landing with less than the minimum required fuel.
While the incident might have resulted in a nervous landing for the flight crew and air traffic controllers, passengers on board were completely unaware of the issue, according to CNN affiliate Nine News, whose reporter Liz Hayes was on the flight.
"Not a hint, not a mention of any impending doom or mayday situation," she 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."
The plane was followed to the gate by emergency services as a precaution.