The Transportation Safety Board of Canada is launching an investigation after an Air Canada flight arriving at Toronto's Pearson International Airport ignored orders to abort its landing as a driverless van rolled onto the runway.

The flight from Edmonton was landing shortly before midnight on Monday.

Ewan Tasker, one of two investigators who conducted an initial probe, told CBC News that they consider the near-collision "quite serious." Though there are hundreds of so-called runway incursions in Canada each year, Tasker said this one is noteworthy because of the driverless vehicle and the risk of a collision.

"That's highly unusual," he said.

An initial Transport Canada incident report posted online Tuesday said that Air Canada Flight 178, an Embraer 190 jet, was finishing its flight at 11:39 p.m. ET when ground radar detected an object on the runway.

Flight crew thought orders were for others

The flight crew was told twice to pull up and go around but the plane landed anyway, the report said.

"Did you hear my two calls to pull up and go around sir?" air traffic control is heard telling the plane's pilot in an audio recording obtained by CBC News.

"I'm sorry, we heard them. We thought they were for somebody else," the pilot said in response.

The object on the runway turned out to be an unoccupied Sunwing Airlines cargo van with keys in the ignition, in gear, with its lights and orange airport beacon on. The Air Canada crew members said they never saw the van.

The report said the van's driver was servicing a Sunwing Boeing 737 and "came out of the aircraft to discover the van was missing." Tasker said the van apparently caused minor damage to the Boeing 737 when its mirror made contact with the outside of an engine. The van rolled slowly for about three minutes and crossed the 60-metre wide runway.

The board hasn't been able to determine yet how close the Air Canada plane and the van got to each other, but Tasker said if the aircraft was on its proper landing path there was a risk the plane would have hit the van before touching down.

He wasn't aware how many people were on the flight, but Air Canada configures the Embraer 190 to hold 97 passengers.

Between 10 and 15 people will conduct the investigation. The safety board's reports can take anywhere from six months to more than a year to prepare, Tasker said.

The board does not assign blame or suggest punishments.

Hundreds of runway incursions yearly

The board has runway collisions on its safety "watch list," calling it one of the nine transportation safety issues posing the greatest risk to Canadians.

In an online video, director of operational services Leo Donati said that from 2001 to 2009 there were 4,100 runway incursions in Canada. Given that there were millions of takeoffs and landings in that time, such incidents are relatively uncommon, he said.

However, the board is concerned that the numbers aren't decreasing.

In 2010, there were 351 incursions. In 2011, there were another 446.

"The TSB is pushing for the advancement of airport procedures and collision defences to reduce these occurrences," he said in the 2012 video. "And until the risk of collisions is sufficiently addressed at Canadian airports, this issue will remain on our safety watch list."