This program, it said in a statement, is “voluntary and anonymous” and an attempt to collect more accurate passenger data and prevent the aircraft from exceeding a “set maximum weight to ensure a safe take-off.”

This is part of a growing trend among airlines, which are deploying this strategy to ensure a plane’s total weight is accurate. While the weight of the aircraft, its fuel, cargo, water tanks and catering are known, airlines want to better pin down the variable weight of passengers and their carry-on bags on individual flights.

But Finnair’s program, which began this week at Helsinki Airport, is already polarizing people on social media. “I do not think that it is intrusive or unnecessary,” wrote one person online, calling the move “reasonable.” Others termed the move “fatphobic” and potentially “humiliating.”

The airline has said the data will remain anonymous. Business and leisure travelers on “selected European flights” and a number on long-haul flights will be offered the chance to participate.

“The collected data is not linked in any way to the customer’s personal data,” Satu Munnukka, head of ground processes at Finnair, said in a statement. “We do not ask for the name or booking number.”

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The total weight of the passenger and their carry-on baggage, their age, gender and travel class are recorded in a database, but “no information is collected that would allow participants to be identified,” Munnukka added. “Only the customer service agent working at the measuring point can see the total weight, so you can participate in the study with peace of mind.”

Other airlines have carried out similar exercises.

In 2013, Samoa Air became one of the first airline to weigh passengers and — controversially — charge a variable kilogram-per-mile rate based on whatever the scale had to say. Last year, Air New Zealand also carried out a weigh-in for its passengers for flight balance calculations.

Korean Airlines faced some passenger backlash after undertaking a similar program last summer, with local media reporting that some travelers said they felt embarrassed to be weighed, while others argued that lighter passengers should be given larger baggage allowances.

Most American carriers have ruled out such measures in recent years, while in the United Kingdom, an aviation start-up has been investigating more precise weight data methods at airports in a bid to save fuel costs and curb flight emissions.

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The weight of customers and their carry-on baggage is generally calculated using average weights confirmed by the Civil Aviation Authority, Finnair said. The alternative option is for airlines to either use their own measurements or use standard weights defined by the European Union Aviation Safety Agency.

Since 2018, Finnair said it has used average weights based on its own measurements, but these estimates need to be updated every five years. “It’s now time to collect updated data,” spokeswoman Päivyt Tallqvist said in an email Friday.

The project began Monday, and “so far we have had some 800 volunteers participating in this — it is great to see that our customers are interested in volunteering in this data collection,” she added, underscoring that being weighed is not obligatory for anyone.

Passengers are rewarded with a memento baggage tag for their participation, she said.

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The survey will be rolled out again in the warmer months, according to the airline, to take into account seasonal packing shifts in clothes.

Once complete, the information will be sent to the Finnish Transport and Communications Agency, Traficom, for validation before the airline can use the data for future aircraft balance and loading calculations between 2025 to 2030, Finnair said.