A Qantas airliner that discovered its weather radar was faulty tailed an Air New Zealand jet across the Pacific on a Wednesday flight from Los Angeles to Sydney, an official said.

The Air New Zealand flight crew provided information about the weather ahead to the Qantas Boeing 747-400 jumbo jet carrying 284 passengers as the two aircraft made the 12-hour journey to Auckland in New Zealand, a Qantas spokeswoman said on condition of anonymity, citing company policy. The Qantas flight later continued on to Sydney, its scheduled destination.

The fault is the latest in a series of high-profile malfunctions and near-misses for Australia's flagship carrier in recent months that have drawn attention to its safety standards.

Network Seven television news reported that the pilot told passengers during the flight that he was "flying blind" across the ocean. Another passenger told the station that the Air New Zealand jet came into view as it flew ahead of the Qantas jet.

The Qantas plane was "a few hours" into its flight when it "experienced a weather radar defect," the company's spokeswoman said.

"An Air New Zealand flight ... was a short distance ahead and it provided the Qantas aircraft with information from its own radar system throughout the journey," she said.

The Qantas jet first landed in Auckland, which was the Air New Zealand plane's scheduled destination, she said. It arrived Sydney about four hours late.

Seven reported that a defective aerial was repaired in Auckland. The spokeswoman said she did not know if the fault was repaired in Auckland or after arrival in Sydney.

She said the fault had never posed any danger.

"None at all. Otherwise they wouldn't have operated the flight," she said, indicating that the jet would have returned to California.