Nadeem Muhammad, 43, was planning to board a Ryanair flight to Italy on 30 January when security staff at Manchester Airport found the device, made of masking tape, batteries, the tube of a marker pen, pins and wires – and which contained nitro- glycerin and nitrocellulose – in the zip lining of his small green suitcase.
Yesterday, he was found guilty at Manchester Crown Court of possession of explosives with intent to endanger life or property.
The court heard police had initially believed the bomb was not viable and, after being questioned by counter-terrorism officers, Muhammad, who was born in Pakistan but had an Italian passport, was released.
He was able to board a flight to Italy five days later.
Superintendent Graeme Openshaw, of Greater Manchester Police’s specialist operations unit, said: “Based on the overall circumstances of his stop and the information presented at the time, police officers determined that there was not sufficient evidence or suspicion to arrest the man and place restrictions on his movement.
“Following subsequent forensic examination of the device carried out by police, it was determined that it could be viable and the man was arrested at the first opportunity. We accept that there were some errors with our assessment of the device on the day and we have already reviewed our practices.”
Mr Openshaw said it was unclear what damage would have been done if the bomb had been detonated once Muhammad was on board the Boeing 737.
The court heard officers had swabbed the device after it was detected when the bag went through X-ray scanners but had found no trace of explosives.
Security manager Deborah Jeffrey put the pipe bomb in her pocket before passing it to police.
An airport spokesman said: “We are proud of the work that our teams do to ensure the safety and security of passengers. In this instance, the actions of our security team led to the detection of a suspicious device.”
Muhammad, of Bury, told the court he had not seen the device before it was found in his bag and it had “nothing at all” to do with him.
Sentence was deferred.