On Friday the 13th, one airline is taking measure of the superstition of passengers as they fly on flight 666 to HEL, the airport code for Helsinki, according to the Associated Press.

Finnair passengers on AY666 to Helsinki must not be too bothered by the superstitions because the flight is almost full.

"Less than 100 years ago, the number 13 did not have this sinister meaning," Ulo Valk, a professor of comparative folklore at the University of Tartu in Estonia, told the Associated Press. "It's quite recent in the north."

The flight, which goes from Copenhagen to Helsinki occurs daily and falls on Friday the 13th twice a year. That date is considered bad luck in many countries and the accompanying flight number 666 also has strong negative biblical associations.

"It has been quite a joke among the pilots," Juha-Pekka Keidasto, a veteran pilot with Finnair who will fly the Airbus A320 from Copenhagen to Helsinki, said. "I'm not a superstitious man.

"It's only a coincidence for me," Keidasto said.

Many airlines take people's fears and superstitions seriously, such as Scandinavian Airlines, and they don't include a row 13 on board. These connotations, however, are a relatively new thing in northern European countries like, and Finnair is among a number of regional carriers that still have a row 13 on board.

"There are 12 hours, 12 months and in Christianity, 12 apostles, and this is a divine number," Keidasto said. "And one more and it brings in a certain element of chaos."

However, passengers on flight 666 to HEL would have a calm flight over the Baltic, with good weather at this time of year.

"It's hopefully smooth skies," Keidasto said. "And if there's some passenger who is anxious about this 666, our cabin crew is always happy to help them."