Air Canada fared well in 2014. After years of widening financial losses that caused its shares to plummet, the carrier has emerged as one of the Toronto Stock Exchange’s best industrial performers. Central to this turnaround has been revenue boost achieved by squeezing more passengers onto its airplanes. Five of Air Canada’s Boeing 777-300s now accommodate 458 passengers, up from the original 359. Other carriers, such as All Nippon Airways and China Eastern have since followed suit, introducing high density seating configurations on their airplanes.

Airlines have found that the benefit to moving more passengers on a single airplane outweigh the costs (e.g., extra meals, additional staff, and most notably, added passenger complaints over less legroom). For Ryanair, this benefit can add up to as much as $1 million annually if each aircraft in its fleet can accommodate eight more passengers. That’s big bucks for an industry that saw a mere $5.94 profit per passenger in 2013. The economics of packing more passengers onto airplanes seems sound, but can the same be said for safety? Are passengers who fly these aircraft more likely to be at risk in the event of an emergency?

Before entering service, new airplane models must pass an emergency evacuation test. This entails filling the cabin with the maximum envisioned number of passengers (played by volunteers), and then on cue, having everyone exit the airplane. The evacuation must be completed within ninety seconds (the time taken for fire to fill a standard cabin) for the test to be successful. Aircraft are certified to carry more than the ‘operationally envisioned’ number of passengers. For example, the Boeing 777-300 can legally carry 550 passengers, considerably higher than the 458 seen in Air Canada’s configuration. Hence, aircraft manufacturers will argue that no additional risk is posed by flying high-density aircraft.

While the test includes some realistic aspects of a crash (e.g., the cabin is strewn with debris and only half the number of exits are made available for evacuation), it neglects critical human factors. These include consideration of passengers who hinder the evacuation process by trying to retrieve hand luggage before exiting the plane and the elderly or handicapped whose movement times are significantly slower. Perhaps most importantly, the test disregards how humans behave when faced by a mortal threat (e.g., fire, toxic fumes). When primal survival instincts take over, people tend to engage in competitive rather than collaborative working relationships. This was documented during the 1984 evacuation of a Boeing 737 in Calgary. Investigators found that amid “some pushing, several people went over seat backs to get to the exit ahead of others already in the aisle.”

Criticisms of testing standards are hardly new. Former American congressman Newt Gingrich once called the approach taken by regulators and industry to evacuation tests “totally out of touch with the real world.” And in an interview with Flight Global, Ed Galea, director of fire safety engineering at the University of Greenwich, concluded that these tests may provide a false sense of security to the travelling public “who may assume that if the aircraft is certified, it must be safe.” A 2013 Transportation Safety Board study, showing that evacuation times during real accidents exceed the ninety seconds required for certification purposes 75% of the time, supports Galea’s sentiment.

Given the additional certification time and cost involved, airplane manufacturers are likely to oppose efforts to impose more stringent testing standards; standards that emphasize inclusion of more realistic aspects of human behavior. Boeing recently argued that its new 787 Dreamliner was similar enough to its previous 767 that an evacuation test certification was unnecessary. However, as airline competition intensifies, the list of carriers using high-density seating for financial relief are likely to increase. In the event of an emergency when seconds count, more passengers onboard an airplane increases the chances of previously neglected human factors complicating evacuation efforts. The responsibility lies with federal regulators to ensure these factors are considered when certifying airplanes as safe to fly. In the event that they fail, less legroom may be the least of passenger concerns.