Why do airlines weigh passengers?

In early February, Finnish flag carrier Finnair announced that it would ask passengers to weigh themselves at departure gates in Helsinki airport in order to collect data that was needed for “the safe operation of flights”.

The policy, which will be in effect between April and May, is voluntary and anonymous, with the airline stating that the data “will only be used to optimise Finnair’s current aircraft balance calculations”.

In May 2023, Air New Zealand announced a similar scheme, asking around 10,000 passengers to step onto the scales as part of an initiative ensure “the safe and efficient operation of the aircraft”. 

But the announcements have experienced some backlash online, with LBC reporting that passengers labelled the data collection “humiliating” and “triggering to people with eating disorders”.

So why exactly might airlines ask passengers to weigh themselves?

Why do airlines ask passengers to weigh themselves?

There are several reasons why airlines need accurate weight data. The main reason is safety – aviation rules state that aircraft cannot take off if they exceed the certified ‘Maximum Takeoff Mass’ that has been specified by the manufacturer.

As it is impractical to weigh every passenger right before take off, airlines gather data on average weight (of both passengers and their hand luggage) in order to determine the total mass of the average flight.

These calculations inform the quality of fuel needed, the flight’s distance range and any potential emergency landing sites. For example, the data collected by Finnair will be used for balance and loading calculations between 2025 and 2030.

The practice is fairly standard within the aviation industry, with many countries’ airline regulators mandating regular updates to data. Airlines can either collect their own data or use official figures from the European Aviation Safety Agency (EASA). Finnish authorities require data to be renewed every five years, and Finnair last weighed passengers in 2018.

What happens to the data?

Passenger data is collected on a voluntary basis, and all data collected is anonymous. Airlines will not link the weights with a customer’s name or booking number, and only the attendant working at the gate will see the figure.

In the case of the data collected by Finnair, it will be sent to the Finnish transport and…