Finnair flights are threatened with disruption over an eight-day period this month, from industrial action being considered by two unions.
Cabin crew represented by the flight attendants' union SLSY and the aviation union IAU have warned of strikes at various points from 15-23 November, as well as an overtime ban.
SLSY says a cabin crew collective agreement expired on 31 October and contract negotiations, being undertaken in the context of Finnair's cost-cutting plan, have broken down.
The union says it has been prepared to discuss cost savings but has been unable to commit to "unreasonable" demands, and accuses Finnair of "dictating unilaterally" employment terms.
Finnair, which is celebrating its 90th anniversary, says it is "surprised" by the strike threat, claiming that unions had "assured us that they would refrain from such action".
Chief operating officer Ville Iho adds: "If the strike goes ahead, it would have a significant impact on our operations. We sincerely apologise for the worry that this strike threat will cause our customers.
"Any such action will of course weaken the chances of Finnair and its staff to survive the fierce structural changes that the whole industry sector is going through."