Cockpit CO2 levels affect pilot flight performance: Study

Higher carbon dioxide (CO2) levels on the flight deck may negatively affect an airline pilot's performance, a study suggests.

Commercial airline pilots were significantly better at performing advanced manoeuvres in a flight simulator when CO2 levels in the cockpit were 700 parts per million (ppm) and 1,500 ppm than at 2,500 ppm, researchers said.

"The entire flight experience is designed around a culture of 'safety first.' Optimising air quality on the flight deck must continue to be a part of that safety equation," said Joseph Allen, an assistant professor at Harvard TH Chan School of Public Health in the US.

The research, published in the Journal of Exposure Science & Environmental Epidemiology, recruited 30 male commercial airline pilots and split them into teams of two.

Each team was asked to perform three 3-hour-long flight simulations that consisted of 21 manoeuvres of varying degrees of difficulty without the aid of autopilot.

Both pilots on each team took a 90-minute turn as the flying pilot during each simulation.

CO2 levels were randomised to either 700 ppm, 1,500 ppm, or 2,500 ppm, and each pilot flew one flight at each CO2 level over the course of the study.

The findings showed that the pilots were 69 per cent more likely to receive a passing grade on a manoeuvre when CO2 levels were 700 ppm compared with 2,500 ppm.

When CO2 levels were 1,500 ppm, the pilots were 52 per cent more likely to successfully perform a manoeuvre than when CO2 levels were 2,500 ppm.

When the researchers compared the difference in pilot performance at 700 ppm and 1,500 ppm, the difference was not statistically significant.

However, they did find that pilots were more likely to successfully perform some of the most difficult manoeuvres at the lower CO2 level.

The study also found that the negative effects of CO2 on flight performance became more pronounced the longer the pilots were in the simulator.

Previous research has shown that average CO2 levels on the flight deck are less than 800 ppm.

However, they have been measured as high as 2,000 ppm on the flight deck and even higher in the cabin during the boarding process, depending on the type of airplane and other factors.