The process is part of the airline's routine five-year update to its average weights measurement to ensure all planes take off safely. Finnair aircraft at Helsinki Airport in Finland on May 22, 2022.

Airlines that use their own measurements must update their data every five years. Finnair last surveyed customers for their weights in 2018. "It's now time to collect updated data," the airline said.

Finnair has begun asking passengers to weigh themselves before flights voluntarily. Critics argue it could trigger people with eating disorders and potentially lead to discrimination.

Finnair is asking passengers to be weighed to collect flight safety data. As of Wednesday, 600 passengers have volunteered for the exercise, the airline said.

The airline will use those numbers for aircraft balance and loading calculations from 2025 to 2030. Each aircraft has a set maximum weight to ensure safe takeoff, according to Finnair.