An Air New Zealand flight that had to turn around because it did not have permission to land in China was the fault of the airline, aviation commentators say.
The NZ289 Shanghai-bound flight from Auckland late last night was turned back about five hours into the journey after it was found the aircraft did not have a permit to land.
A statement from Air New Zealand said: "It is normal process to get a flight plan cleared by local authorities prior to departure and this was done on this occasion and was approved by Chinese authorities.
"Unfortunately, it was discovered during the flight that this particular aircraft did not, in fact, have the necessary permit to land.''
Independent aviation commentator Irene King said such an incident was highly unusual and knew of only one other instance of this happening with an Air New Zealand aircraft.
She said it was likely that although the airline would have filed for an aircraft to land, a different aircraft was suddenly listed to land on the other side - something Chinese authorities would not have accepted.
"China's very restrictive to filing applications for landing slots. Normally, the airlines are obsessive with their systems - filing landing slots applications days, weeks, months in advance.
"Clearly, there's been a serious administrative cock-up for this to happen."
King said it was well-known among airlines and the aviation world that the Chinese were "very particular'' and strict about their airspace; so it was the airline's mistake to make.
"It's just highly unusual. Basically, it should not have happened.
"Under the Civil Aviation Act, under compensation, the passengers can apply for up to 10 times the amount of compensation because this is not an act of God or an engineering problem or technical problem.
"This is clearly an administrative - well, I call it a cock-up and the passengers should file and are entitled to compensation. It should not have happened.''
Veteran flight instructor Warren Sattler reiterated her comments; saying Chinese authorities were sticklers for following rules.
"It might've been listed as a 777 and they might've taken a 787 instead.
"The Chinese - because of all the military airspace up there - they're very, very particular.
"This is only a pure guess on my part, that Air New Zealand - for whatever reason - may have decided instead of putting on a 777, putting on a 787."
Eric Hundman, an assistant professor at the Shanghai campus of NYU (New York University), told the Herald the flight took off from Auckland as scheduled close to midnight last night but "midway through our flight, the pilot informs us that Chinese authorities had not given this plane permission to land, so we needed to turn around.
"A permitting issue, supposedly," he said.
The flight returned to Auckland about 9.30 this morning, Hundman said.
Shortly after 11.30 this morning, Hundman was sent a text from Air NZ saying: "As you were advised on board, the aircraft operating your flight did not have regulatory approval to land in China and was required to return to Auckland."
A meagre compensation package included a $30 meal voucher.
Prime Minister Jacinda Ardern had not been briefed about the situation when asked about it at the Big Gay Out event in Auckland.
She said it sounded like an operational matter for the airline.
Foreign Minister Winston Peters declined to comment on the matter, or on whether he had been briefed by the Ministry of Foreign Affairs and Trade (Mfat), and he referred all questions to the ministry.
"The Government is aware of this matter," an Mfat spokeswoman said.
"Air New Zealand has clearly explained this was caused by a technicality in the flight plan permitting process, and any questions should be put to the airline."