Finnair is asking for a few volunteers, not to take a later flight, but to step on a scale before boarding the plane.

The Finnish airline told CNBC that it has asked about 180 passengers to weigh in before flights from Helsinki Airport this week and it needs about 2,000 travelers to get an accurate read on passenger weights and their carry-on bags.

The study will continue through spring 2018, Finnair said, because it wants to collect data when travelers are carrying heavy winter coats and when they are traveling lighter in warmer weather. The information will be kept anonymous, the airline said.

The aim of the weigh-ins, which might be more familiar to travelers who have flown on small planes, is to update nearly decade-old data on average passenger weights as it expands its route network and needs to accurately forecast payloads and how much fuel it requires.

"We have a strong safety culture at Finnair, and are also a very data-driven organization, so we want to ensure we have the best possible data in use in aircraft performance and loading calculations," Finnair said.