Before Shanghai Airlines flight FM9311 departed from Shanghai Hongqiao International Airport Thursday, a passenger plunked himself down in a window seat that was assigned to someone else. When confronted, the passenger, a PhD candidate at a well-known university in the city, claimed he had the right to the seat because he got there first, according to a report in the Xinmin Evening News.

When a flight attendant asked the passenger to go to his assigned seat, he refused. He argued that no one has assigned seats on the bus, so why should he give up his seat on a plane if he got there first?

The news story did not state whether the passenger had never been on an airplane or was just making excuses.

The flight crew spent 20 minutes trying to coax the passenger to his assigned seat before revoking his ticket and calling the airport police to take him away. The flight ended up being delayed for two hours because of the incident, the report said.

These kinds of cases have been in the news recently. On February 23, a flight from Beijing to Chengdu, Sichuan Province, was delayed for two hours because two passengers got into an argument over their seats before departure, the Beijing Youth Daily reported.

On January 10, several passengers panicked while waiting for their delayed flight to depart, so they opened three of the aircraft's emergency doors in a hairbrained scheme to escape the plane before takeoff, according to a report on news.sina.com.cn. The airline had to cancel the flight, and police took 25 passengers in for questioning.

These passengers not only inconvenienced other people on their flights, they also disrupted operations at the airport, which can cause wide-ranging problems.

Take Shanghai Pudong International Airport as an example. At least 1,166 flights took off from and landed at the airport every day last summer, according to the Shanghai Airport Authority. That's 48 flights arriving and departing each hour, on average. With such a high frequency of takeoffs and landings, the slight delay of one flight can delay other flights.

Passengers who cause disturbances on a flight are also breaking the law. People who disrupt order on a flight or at the airport can be punished with fines or detention, according to the Regulations of the People's Republic of China on Administrative Penalties for Public Security. China's rules for civil aviation security prohibit passengers from seizing seats, disrupting the order on a flight and jeopardizing the safety of the flight. In these cases, the airplane's captain has the right to take action to control these troublemakers.

That's how it is supposed to work. However, flight crews often take a softer approach. Typically, they let problems pass, or just ask troublemakers to apologize. If police are involved, they usually let offenders off with a lecture and a warning.

According to the Shanghai Observer, the authorities punish few of these offenders. Some even end up receiving compensation from the airlines for their own supposed inconvenience. Huang Lihua, an assistant professor at Sichuan University who specializes in aviation law, believes that Chinese airlines lean toward leniency when dealing with disruptive passengers.

With the growing number of flights arriving or departing from the city's airports, it is critical that airlines take a harder stance against troublemakers.

Passengers should know better than to sit in a seat assigned to someone else, tamper with the airplane's emergency facilities or disobey the flight crew. If passengers insist on being unreasonable, the crew should take swift action to remove them from the flight.