"We learned the pilots did not follow our standard operating procedures designed to eliminate navigational errors," First Air said in a release Thursday.
"As a result, those pilots are no longer employees of First Air."
The Boeing 737 left Rankin Inlet, Nunavut, on a routine flight to the territorial capital of Iqaluit on March 31. It was carrying 19 passengers and four crew when something went wrong.
"We're still working to find that out," said Peter Hildebrand of the Transportation Safety Board. "There were a number of things working together here."
The airplane was being guided by a GPS system, which fed data into a flight management system. In turn, the system directed the plane's autopilot.
"There seems to have been some problem somewhere and that led to an airplane that drifted off track," Hildebrand said.
The plane drifted so far to the north, he said, that its landing was about 20 minutes late.
Those aboard were not in danger, said the company. Hildebrand said the plane had enough fuel to make it all the way to Goose Bay in Newfoundland and Labrador.
Hildebrand added that the plane involved is the only one in First Air's fleet with that particular model of flight management system.
First Air said procedures have been changed as a result of the mistake.
"We have gone to great lengths to update and strengthen our standard operating procedures to ensure our pilots have the tools they need to fly safely," the airline said. "We have also increased in-flight oversight using data monitoring tools."
Hildebrand said no formal investigation has been launched.
"We're gathering data and working with the company. If we see at any time there's a need for a system-wide response on this, we can change our stance."
First Air flies throughout the Canadian North and into some southern cities. It is wholly owned by Makivik Corp., which manages land settlement money from the James Bay Agreement for the Inuit of northern Quebec.