New Zealand's national airline, Air New Zealand, is, from this week until July 2, asking passengers to voluntarily step on the scale before boarding the plane on any of its international flights. The intention is to weigh 10,000 passengers in a month so pilots can better understand the weight and balance of their planes before takeoff. The airline weighs everything to the nearest millimeter. “We weigh everything that goes on the plane, from cargo to onboard meals to luggage in the hold,” said Alastair James, the airline's cargo control enhancements specialist, it's a statement.
And it is that making a mistake in the calculation of the weight that an airplane transports – that of the passengers, their luggage and the cargo – can have disastrous consequences both for the pocket of the airlines and for the safety of the passengers and the crew.
This is what happened, for example, on January 8, 2003 when Air Midwest flight 5481 crashed into a hangar after taking off from the Charlotte-Douglas airport (North Carolina, United States) and killed all its passengers. occupants.
The investigation found that one of the causes of the accident was that the pilots did not realize that the plane was overloaded. The reason for the error was that for the calculation they used outdated estimates –but approved by the Federal Aviation Administration– of the weight per passenger, which had not been revised since 1936, and which were 9 kg less than the actual average weight of Americans in 2003.
Even today, most airlines rely on average mass estimates to calculate the total weight of an aircraft's passengers, using established figures that can vary from country to country.
“For customers, crew and carry-on bags, we use average weights, which is what we get from doing this survey,” James said.
In fact, this is a requirement of the New Zealand Civil Aviation Authority, which gives airlines several options for estimating passenger weight.
One is to conduct regular surveys, like the one Air New Zealand is doing, to establish an average weight. Another is to accept a standard weight established by this same Authority. Currently, the weight limit in New Zealand for people over 13 years of age is 86 kg including hand luggage. Said Authority last updated this data in 2004. Then the average weight was 77 kg. Statistics show that New Zealanders are weighing more and more.
The latest national health survey placed the rate of obesity in adults at 34%, compared to 31% the previous year and that of childhood obesity increased to 13%, compared to 10% also the previous year.
In any case, if this calculation is not done correctly, the consequences for safety may be those that have already been explained, but also that airlines often use more fuel than is essential, whose weight must also be taken into account.
According to the British company Fuel Matrix, for most flights, up to 1% more fuel is loaded than necessary. This represents an increase of between 0.3% and 0.5% more fuel cost due to the additional weight that this entails. And more gasoline means more money spent by the airlines and more emissions.
In the case of the New Zealand company, the weighing will be anonymous and not even the passenger himself will know what it is. There will be no screen visible anywhere, the airline has promised, and the data will be anonymous even to its staff. .
And it is that even with all the precautions and precisions when calculating the weight of everything that travels on a plane, sometimes things go wrong. In July 2020, a TUI company flight took off from Birmingham to Mallorca with 187 passengers with less engine thrust than necessary. The reason was that the pilots thought that the plane weighed 1,200 kg less than it really did, and all because the software that made the calculations, based on the information of the tickets sold, counted 38 adult passengers (69 kg each). as if they were children at 35 kg on average.
