The plane took off near Hesquiat Lake, north of Tofino, Friday morning around 10:20 a.m. PT and failed to arrive at its destination of Gold River, in Vancouver Island's interior.
The plane is a DeHavilland Beaver and belongs to Air Nootka, based in Gold River.
A spokesperson from the airline has confirmed with CBC News that one of their planes is overdue.
Sean Morris, air search co-ordinator with the Joint Rescue Co-ordination Centre, said the pilot sent out a distress call shortly after takeoff.
In addition to the pilot, there were five passengers on board. It's believed the passengers were hikers.
Ground crews, the coast guard, and some local First Nations bands are helping with the search, but officials say low clouds and windy weather are hampering their efforts.