Jet2.com airlines suspended several staff as the news reached the media and senior officials of the airport and airline.
An investigation has been launched and the incident has prompted concerns from the highest levels of government. Officials declined to comment further on how many number of people are suspended due to negligence.
A Manchester Airport spokesman said: "This extremely serious matter is now being urgently investigated by officials from the airport and airline. It is clear that documentation has not been checked correctly at security and the boarding gate." "He was with a large group of other children, he appeared to be in a family group - for whatever reason he wasn't checked," spokesman added.
Justine Greening, the Transport Secretary, told the BBC: "This is an unusual and serious breach and we are keen to find out what has gone on."
Liam had run away several hours earlier when his mother was busy in shopping at Wythenshawe Civic Centre. That was the time when the boy managed to make his way to the airport.
He followed a family when he got to the packed terminal 1, and that security staff scanned him but failed to realize he was on his own and had no boarding card.
And then Liam went to one of the gates where passengers were boarding Jet2.com flight LS791 to Rome, and managed to escape security check without carrying a passport or boarding card.
It's a standard procedure of the cabin crew to carry out a final head count, ensuring that the number of passengers and the boarding cards match up. It seems that Jet2.com crew failed to do the task properly.
It was left to the passengers in the flight to discover that the boy was alone and they alerted the cabin crew. The captain immediately radioed a message back at the Manchester airport about the boy, while the police informed his mother that he is safe and secure but right now on a plane to Rome.
A Manchester Airport spokesman told that the boy was kept in the airplane in Rome and sent back on the same flight to Manchester where his mother was waiting for him.
A Greater Manchester Police spokesman said: "Shortly before 12.40pm on Tuesday... police received a report of a missing 11-year-old boy. The boy was last seen by his mother in a shopping centre in Wythenshawe.
"Officers launched inquiries to trace him, but later became aware that the boy was seen on an aero plane.
This article is copyrighted by Travelers Today, the travel news leader
