Mathieu Larocque, spokesman for the Canadian Air Transport Security Authority, said staff in Edmonton should have contacted police right away, not four days later.
He said a review was conducted after the incident last fall and some screening employees were suspended.
"There were people disciplined and they were required to take extra training," Larocque said Wednesday. "The procedure is to call the police and it didn't happen or it happened very late in the process."
News of the foul-up only made headlines this week. Federal Transport Minister Lisa Raitt issued a statement earlier Wednesday calling the incident unacceptable.
"The safety of Canadians and the travelling public is our government's top priority," Raitt said. "This individual should not have been allowed to board his flight, and it is unacceptable that CATSA waited four days before seeking the RCMP's assistance."
She said she planned to call the president of the agency to discuss the matter further.
Skylar Murphy of Spruce Grove, Alta., pleaded guilty last month to possession of an explosive substance while at the Edmonton International Airport on Sept. 20. He was 18 at the time, but has since turned 19.
Murphy was sentenced to a year of probation and fined $100.
Court documents describe the material seized from his carry-on luggage as "black powder" and some reports say it was a 15-centimetre pipe bomb with a fuse wrapped around it.
CBC and The Edmonton Journal quoted sources as saying a screening officer tried to return the device to Murphy when it was found, but the teen didn't want it back.
The media outlets reported Murphy made the device while fooling around with friends and mistakenly left it in a bag he was taking on a trip to Mexico with his family.
RCMP spokeswoman Josee Valiquette said officials with the security authority notified police on Sept. 24 about the seizure. Officers arrested Murphy on Sept. 27 at the airport, following his return flight home.
Larocque said it's procedure for screening staff to immediately call police if they find something suspicious. "Our screening officers are not police officers and they can't charge anybody with a crime."
Officers are stationed at major airports. It's up to them to decide if a passenger should be arrested or allowed on a plane, said Larocque.
He said training for screening staff across the country is being updated to emphasize the procedure.
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