Skylar Vincent Murphy was caught with the pipe bomb on Sept. 20. Security took the explosive away, but Murphy was allowed to continue on his flight.
Canadian Air Transport Security Authority (CATSA) alerted RCMP to the case four days later. Murphy was arrested by Leduc RCMP on Sept. 27.
In an email response to questions from CBC News, CATSA spokesman Mathieu Larocque did not address why Murphy was allowed to get on the plane.
"Screening officers do not have the authority to apprehend or detain passengers," he wrote. "When they see something potentially illegal, the(y) contact the police."
On Dec. 5, he plead guilty to the charge and was sentenced to one year of probation and a $100 fine.
He is also prohibited from possessing explosives, firearms or ammunition for one year and must also make a $500 donation to the University of Alberta burn unit.