Image: Kyrre Lien / EPA

The Safety Investigation Authority of Finland (Otkes) has begun an initial investigation into the case of a Norwegian airline plane that slid off its designated runway during landing at Helsinki-Vantaa Airport on Tuesday.

None of the 166 passengers on board were injured during the unusual turn of events.

Otkes communications chief Sakari Lauriala says that the preliminary investigation will take at least a week, during which both of the plane's black boxes will be analysed and the pilot inverviewed.

"After this initial probe we'll known whether to start a full-scale investigation," Lauriala says.

Otkes investigations usually only begin in cases that appear especially severe.

Plane rolled onto lawn

Air traffic authority Finavia says that the DY4287 flight from Stockholm to Helsinki was scheduled to arrive at 6:25 pm Tuesday evening, but was delayed, arriving 40 minutes late at 7:10 pm. For reasons still unknown the plane did not stop on the runway but overshot the runway, ending up on the grass.

The plane was towed off the grass by tractor and the passengers exited the aircraft around 8 pm, Finavia reports.

Lauriala says that events of this kind are quite rare, but it has investigated similar landings at Helsinki-Vantaa Airport in 2012 and at Lappeenranta in 2008.