At least two passengers were found smoking aboard an aircraft from Chengdu to Beijing on Sunday and they got no punishment. Isn't it unbelievable?

Several passengers on board the same flight protested and demanded an apology after the plane landed in Beijing, according to a report by the Beijing News. According to the report, crew members stopped the smokers but did not take any other measures. Some passengers told the reporters that their recordings show the captain said: “Since you've landed safely, why bother to ask for more (explanations)?”

The airline company involved, China United Airlines, confirmed later that two people indeed smoked aboard, with one smoking in-flight while the other lit up after the plane temporarily landed in Taiyuan. Crew members stopped the smokers and closely monitored the cabin during the flight, according to the statement the airline issued on Monday.

It is a common sense that smoking aboard a plane is an utterly dangerous behavior and must be forbidden. Both regulators and crew members should hold zero tolerance towards such flight safety-endangering behavior.

The incident leaves at least three questions unanswered.

First of all, how did the smokers manage to get their matches past the security check at the Chengdu airport? Indeed, compared with lighters, matches are technically harder to find during security checks. It should not be an excuse for the failure of the airport security personnel to pick them up, because such a loophole, seemingly small as it is, can be made useful by potential terrorists to launch attacks.

Second, why did the captain and other crew members fail to take any other measures after smoking was found? When the plane landed at Taiyuan airport temporarily, it would have been reasonable for the captain to demand an investigation from local police and require the airport to carry out the security check again to ensure there would not be any other dangerous things left on the plane. Third, is it proper for the captain to take the matter so lightly? According to recordings by some passengers, the captain obviously did not think smoking aboard is something serious, so long as it is stopped. Such a dismissive attitude is also reflected in the statement of the involved company, which is a core factor leading to the protest by some angry passengers.

The regulators must step in immediately to show to the public whether the crew members and the company involved had any rule-breaching activities during and after the flight.

Legislators also need to revise relevant laws and regulations governing flight safety to mete out more serious punishments for those who deliberately violate the law.

There have been several domestic cases involving passengers smoking on board a flight, in which they were mostly fined 200 yuan ($32) each, with a small number of passengers detained for seven days, according to recent media reports.

Given the rising income levels of many Chinese, especially the rich who often travel by air, a 200 yuan fine is far from being truly deterring. If the law is too lenient to those who endanger flight safety, it would become a de facto encouragement for their dangerous behavior.