Would you board flight 666 to HEL on Friday the 13th? For superstitious travellers, that might be tempting fate. But Finnair passengers on AY666 to Helsinki apparently were not too bothered. Friday's flight was almost full.

"It has been quite a joke among the pilots," said pilot Juha-Pekka Keidasto before flying the Airbus A320 from Copenhagen to Helsinki. "I'm not a superstitious man. It's only a coincidence for me."

The daily flight AY666 from Copenhagen to Helsinki falls on Friday the 13th twice in 2013. Friday the 13th is considered bad luck in many countries and the number 666 also has strong negative biblical associations.

Some airlines, such as Scandinavian Airlines, take such fears seriously and do not have a row 13 on board. However, the negative connotations are a relatively new phenomenon for northern Europeans, and Finnair and other regional carriers such as Norwegian and Estonian Air keep row 13.

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

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

Passengers on flight 666 to HEL should have a calm flight over the Baltic at this time of year. "It's hopefully smooth skies," said Keidasto. "And if there's some passenger who is anxious about this 666, our cabin crew is always happy to help them." The flight later landed safely.