A recent mishap is not only costing two Chinese pilots their jobs, but will also cost their employer Air China quite a lot of revenue. An Air China flight on July 10 from Hong Kong to Dalian, in Northeast Liaoning Province, dropped 25,000 feet in ten minutes, leading to oxygen masks being released in the cabin. After the accident it was suspected that pilots smoking in the cabin was the cause of the incident.

A pilot on an Air China flight smoking an e-cigarette inadvertently led to a drop in 25,000 feet and the release of oxygen masks

It was later revealed that one of the pilots attempted to turn off a circulation fan to prevent the vapor from his electronic cigarette from reaching the main cabin. However, the pilot accidentally turned off the air conditioning of the cabin, leading to a depressurization alert. This forced the pilots to lower the altitude of the Boeing 737 as quickly as possible.

As a result, the pilots involved have had both of their pilot licenses revoked. The Civil Aviation Administration of China (CAAC) has also fined Air China 50,000 yuan ($7,448) and mandated that its narrow body Boeing aircraft fleet capacity be cut by 10 percent. This would result in an estimated reduction of 5,400 flight hours per month, and it’s not clear when this restriction will be lifted. The airline will also undergo a three month safety evaluation.

How much the cut in flight hours will cost Air China is unknown, but it’s likely to be substantial

The fine is not a major burden for Air China. However, the reduction in flight hours will result in a substantial loss of revenue.

This isn’t the first high-profile airplane mishap to come out of China in the past few years. The difference, however, is that most have involved unruly passengers or those ignorant of the rules of air travel.

For example, a passenger on a Lucky Air flight to Mianyang in Sichuan Province last month opened the emergency exit of the plane after it had landed. The passenger had hoped to get some fresh air while waiting to exit the plane. Ironically, that passenger was questioned for 15 days by police and fined 100,000 yuan, twice that of Air China for its recent debacle.

China has been host to many high-profile flight-related incidents, but the overwhelming majority have not resulted in any potential harm to passengers

Fortunately, most of these incidents have been relatively benign and have not resulted in danger to passengers. Even the recent Air China incident, while dramatic, did not result in any real danger to passengers. The plane was in no way damaged and the cabin maintained air pressure. The plane’s rapid descent was also within protocol. A pilot quoted by the South China Morning Post noted that the rapid descent of the aircraft was the appropriate response to any depressurization warnings. The pilot’s goal in that situation would be to descend to a point where air outside the plane would have sufficient oxygen for breathing.