An Air Canada flight has landed in Vancouver, British Columbia accompanied by an unlikely pair of escorts -- a pair of Canadian fighter jets.

Air Canada Flight 109 touched down at Vancouver International Airport about half an hour late, at approximately 4:15 p.m. PT on Tuesday afternoon.

Reporting from Vancouver, CTV's Sarah Galashan said few details of the circumstances surrounding the escort have been released.

"We've not been told any reason why this escort happened," she said.

What is known is that two Canadian Air Force CF-18s fighters from CFB Comox escorted the Boeing 767 as it flew into Vancouver.

One planespotter who witnessed the landing told CTV he'd never seen anything like it before.

"I was out watching the plane," he said, describing the sight of the airliner making its final approach escorted by a pair of fighter jets.

"As soon as it landed they (fighters) overflew the runway and then headed west."

RCMP Cpl. Peter Thiessen confirmed to The Canadian Press the plane had landed safely, but would not say whether it was the target of a specific threat.

"There was an aircraft escorted by two fighter jets," he said. "Yes, we are investigating as to why.

"We are speaking with the pilot and other people related to that flight."

The Air Canada flight had originated in Halifax, Nova Scotia, with a stopover in Toronto.

One Toronto-bound passenger told CP that the leg from Halifax, although delayed by about an hour, was normal.

But, he noted, all passengers were asked to leave the plane in Toronto, "while the plane was cleaned."

According to CTV Vancouver's Lisa Rossington, officials at North American Air Defense Command said the escort was a response to a potential onboard threat that turned out to be unfounded.

Earlier statements from NORAD had suggested the jets were scrambled as part of a "routine air sovereignty operation -- a standard operation post-9/11."