The family of a 4-year-old boy who was able to pass through security and board a plane in Beijing without a ticket was released without charges, the civil aviation watchdog said on Tuesday.

The incident, which contributed to a five-hour delay for Juneyao Airlines flight HO1252 from the capital to Shanghai, happened at Beijing Capital International Airport on Sunday.

"A family of five-two parents and three children - had never taken a plane before, and the parents had misunderstood the airline's rules, believing a child under 1.2 meters tall did not need a ticket. So they did not buy one for their 4-year-old son," said Li Jicheng, deputy director of safety of the Civil Aviation Administration of China.

The error was discovered only when a flight attendant counted an extra passenger during a head count before departure.

The family was removed from the flight and taken to a police station at the airport. For safety reasons, all passengers were then asked to again go through a security check as an inspection of the aircraft was conducted.

Police were satisfied that the family did not attempt to sneak onto the flight without a ticket and they were released the same day, the CAAC said.

"The civil aviation department will examine loopholes after the incident. Passengers should learn civil aviation rules and requirements," Li said.

Flight HO1252 was scheduled to leave Beijing at 6:55 am on Sunday and finally took off at noon.

"The weather conditions also contributed to the delay. The child incident caused a delay of about an hour and a half," Li said.

Juneyao Airlines released a statement on Tuesday saying that compensation had been offered to the passengers.

The airline also reminded passengers that everyone needs a ticket to travel.

Jiang Chenglong contributed to this story.

luowangshu@chinadaily.com.cn