For the fourth time in five days, another WestJet flight was forced to make an emergency landing, this time diverted to Calgary, due to an alleged bomb threat.

WestJet Flight 722 departed from Vancouver, bound for Toronto on Wednesday night when a threat was called in, forcing officials to make a decision to land the plane early in Calgary.

All 30 passengers and five crew members got off the Boeing 737-700 from the tarmac, where they boarded a bus bound for an undisclosed location where they could be interviewed by police.

No one was injured.

WestJet is calling this and the three other threats against its flights as criminal investigations.

Officials say that a lot of rumours and speculation are being generated by the threats, but they aren’t making any comment on them.

They are also not releasing any details on how they are conducting the investigation.

Passengers at Calgary International Airport, however, aren't too concerned about security at Canadian airports.

"We have a very safe system in Canada and I wouldn't be worried at all," one passenger said on Thursday.

Other passengers say that they are happy with the way that affected airlines are dealing the bomb threats and agree with the methods used to resolve the potentially dangerous situations.