On Monday, Air New Zealand's longest-ever flight touched down in Auckland - several passengers' luggage did not.
Around 50 passengers aboard NZ1, the inaugural New York to New Zealand service, were told that their bags had been left in the States.
The airline issued an apology, saying "due to adverse weather" some customer bags were not loaded in order to take on extra fuel to make the challenging 18 hour flight.
This is the first time Air New Zealand has flown the ultra-long haul service. Being that it's the fourth-longest route in the world, and faces substantial prevailing headwinds, some aviation and meteorological experts have said this won't be the last of the route's luggage woes.
But how does Air New Zealand - or any airline - decide which passengers and luggage to prioritise?
For some passengers, it appeared like it was a lottery as to whether their bags were offloaded in New York.
One traveller who had been returning from holiday in the US told the Herald that, despite her and her husband's luggage being underweight, neither of their bags arrived in Auckland.
Meanwhile, a travelling sports team had no issues with the service.
"We had no issues with our personal nor team luggage," the Jamaican Netball coach Leonie Phinny, said. This was a "direct booking" from Jamaica for team members due to take part in delayed test matches in Auckland on Wednesday.
Some travellers claimed that some passengers in premium cabin classes had not been affected by the weight issues, and had apparently been prioritised in the decision of whose luggage was offloaded.
"We were told there was media and some VIPs on the service," said one passenger.
It felt as if there were two tiers of passenger - those who had a seamless experience, and those who waited over an hour only to be told their luggage was not on the flight.
"It was weird to be greeted at Auckland by reporters and hype celebrating the success of the flight, however, things were a shambles outside the flight itself."
Although uncommon, sometimes an airline must decide to offload luggage for weight and safety reasons. Photo / Liu Revutska, Unsplash
When are flights overweight?
It's not a question of passengers turning up to check in with too many bags. The maximum load weight for flights is a shifting bar.
Weight restrictions are a concern for all flights. While uncommon, it is not unheard of of flights having to offload luggage, and sometimes passengers, for 'weight' or 'balance' reasons.
While passenger flights have a fairly generous allowance for luggage and cargo, calculations for maximum weight are made on a flight-by-flight basis. Local factors, including air temperature, elevation, runway length and projected flight path can all affect the weight and loading of the plane.
In the case of NZ1, it was bad weather that caused the airline to offload "excess" weight.
"The flight from New York to Auckland is always longer due to headwinds," said a spokesperson for Air New Zealand. "In this instance, the flight path avoided a weather system."
This means that someone is given the unenviable task of choosing the unlucky passengers' luggage to offload. Who chooses and how they decide is less of a science.
Ground handling agencies prioritise luggage loading according to airline's protocols. Photo / Caller Macarone, Unsplash
Whose luggage gets bumped?
Many passengers question whether cabin class, frequent flyer membership, and luggage weight had any role in prioritising bags for transport.
Luggage handling at busy international airports is a surprisingly complicated task.
Local ground handling agencies are contracted by airlines to load and distribute luggage and cargo on regular services. If it is determined that a flight is overweight, ultimately it is the airlines operating the flight which decide how to prioritise.
"Decisions about offloading baggage are made by airlines," said a spokesperson for Menzies Aviation, which handles ground logistics at some of the world's largest airports.
This can be a pure weight-to-passenger ratio, prioritising luggage of groups over individual carriers and, in some cases, cabin class and standing with an airline's loyalty programme can play a factor.
Each airline has a protocol for handling overweight services. This is a closely guarded secret. Air New Zealand did not comment upon its procedures for bumping passengers or luggage.
However, it did say that a number of measures were taken to avoid weight issues. This includes selling just over two-thirds of the seats.
"We made some adjustments to the number of seats sold to compensate for the extra fuel required to go such a long distance. We also do not carry cargo on the southbound leg," the airline told the Herald.
Air New Zealand said it had launched a review of its ultra-long-haul flights to reduce the chance of this happening again.
A source familiar with the issue said that while airlines will have guidelines on eliminating excess weight, it is the captain and flight crew who must decide on any changes to cargo and luggage for weight purposes.
Ultimately, it is the captain of each plane that makes the final call.
