Stale air in cockpit may impede pilots
Carbon dioxide levels can hinder their performance
That poorly ventilated conference room isn’t the only place with the potential for sick-air syndrome.
Airliner cockpits can also have levels of carbon dioxide elevated enough that in simulations it causes pilots to fail test maneuvers at higher rates than normal, a new Harvard University study has found.
The first-of-its-kind research suggests that current regulations aren’t adequate to assure there’s enough fresh air in airline flight decks and raises questions about whether even moderately elevated carbon dioxide levels could impact safety, said Joseph Allen, an assistant professor at Harvard’s School of Public Health and lead author of the study.
“It’s clear that the air quality in the cockpit can have an impact on performance,” Allen said. “It’s clear we haven’t been thinking about it too deeply in terms of the impact on pilot performance. Now that we know, I think we’re obligated to ask those next sets of questions and really understand it.”
In recent years, studies have shown that even an increase of a few hundred parts per million of carbon dioxide in the air we breathe causes people to test lower for cognitive skills. But until the latest study, pilots and airline cockpits hadn’t been examined.
Normal levels in the atmosphere are 400 parts per million. Concentrations of the colorless, tasteless gas can rise in poorly ventilated spaces where people exhale it — such as crowded airliners.
Carbon dioxide levels reached as high as 1,400 parts per million on five percent of airline flights the European Aviation Safety Agency tested, according to data it released last year. The average was 603 parts per million, just slightly higher than levels found in the air.
For the Harvard study, 30 pilots were recruited to fly multiple three-hour segments in a special flight simulator in which carbon dioxide levels could be manipulated. Performance on 21 maneuvers — ranging from making a steep turn to handling an emergency engine fire — decreased as carbon dioxide levels rose, according to the study. Flight examiners certified by the Federal Aviation Administration rated the pilots’ performance.
At 700 parts per million, pilots were 69 percent more likely to correctly perform the maneuvers compared to when they were breathing carbon dioxide at 2500 parts per million. At 1,500 parts per million, they were 52 percent more likely to pass compared to the higher level.
The study was published Wednesday in the Journal of Exposure Science & Environmental Epidemiology.
Allen, who is also co-director of Harvard’s Center for Climate, Health, and the Global Environment, took pains to say that air travel is extremely safe. There has been only one passenger death on a U.S.registered airline in more than nine years and there’s never been any evidence linking routine carbon dioxide levels to a crash.
However, several of the few recent fatal accidents that have occurred involved puzzling lapses in pilot performance, according to accident investigation agencies.
At the very least, Allen said, regulation agencies like the FAA might want to study the issue and compare the growing research on the effects of carbon dioxide with the existing U.S. regulations on aircraft design.
“The goal is to optimize conditions for a safe flight,” he said, “and the air in the cockpit has to be a part of that conversation.”