07/03/2015 02:43 EDT | Updated 07/03/2016 05:59 EDT

WestJet bomb threats likely a 'hoax or a vendetta' against airline, expert says

Five threats, including four bomb scares, have targeted WestJet flights this week — the latest on a flight from Las Vegas to Victoria on Thursday night.

WestjJet Flight 722 landed safety at the airport and no explosives were found on any of the aircraft.

Passenger Sandra Strawson was heading home on the flight, which was delayed for two hours while RCMP searched the plane.

"They just announced there was a problem, possibly a bomb threat, that we all had to wait for further directions," she said. "And then we had to get off the plane — without luggage, without cellphones — and we had to wait again inside."

Strawson said she didn't feel like it was a real bomb threat because passengers were kept inside the nearby terminal, but she didn't feel they were being properly informed.

There is still no indication whether any of the threats called into the airline are connected. The airline says it will not speculate on why it has received the false threats. 

Westjet believes the threats are a hoax but decided to divert the planes out of "an abundance of caution."

'Either a hoax or a vendetta'

"These events are now active criminal investigations, and we will make no comment on them while underway," said WestJet spokesperson Robert Palmer on Friday.

Transport Minister Lisa Raitt also declined to comment on the investigation but said the safety and security of Canadians is a top priority.

"Airlines and airports have protocols and plans in place for dealing with these sorts of threats," she said in a statement.

"Threats made to aircraft are violations of the Criminal Code of Canada‎ and those found responsible will face the full force of the law."

Bryce Fisher, a pilot and a security consultant, says whoever called in the threats needs to be found soon and prosecuted.

"It's either a hoax or a vendetta against WestJet by maybe a disgruntled customer or a former employee, or even a current employee for that matter," Fisher said. "If it's a hoax, it could be one or two people, or you could have ... copycats."

Calgary police are working closely with RCMP to try and find the person who made a bomb threat against WestJet Flight 722, which was en route from Vancouver to Toronto Wednesday night when it made an emergency landing in Calgary.

Diverting a flight can cost thousands of dollars

A Calgary police spokesperson said they are working with officers in other cities affected by diverted flights over the last week, including Saskatoon and Winnipeg.

Six passengers were injured during an emergency evacuation during the Winnipeg flight.

"It's unfortunate that one person can cause so much disruption," said Leon Cygman, who runs the aviation program at Mount Royal University.

He says the decision to divert a plane is not taken lightly, and it can cost an airline tens of thousands of dollars.

"I would say that there is something more than we are being told. The threat would have to be fairly credible for them to divert the plane and put it down," said Cygman.

Security expert Peter St. John says airlines have no choice but to land immediately if there is a credible threat to a plane.

He says there are up to 700 bomb threats a year in U.S., and it likely happens in Canada a lot too.    

"Legally, of course, the airlines are not going to talk about all the hoaxes that come in. It's only going to talk to some of the really credible ones out loud," said St. John.