Numerous airlines hastily changed their policies Thursday to require that two crew members be in the cockpit at all times, after the co-pilot of a Germanwings flight apparently deliberately crashed a plane, killing 150 people, after having locked out the captain.
The U.S. Federal Aviation Administration for many years has required that at least two qualified crew members be in the cockpit throughout every flight. But that's not the case in other parts of the world.
John Cox, chief executive of Safety Operating Systems, a Washington-based aviation safety consultant, said Tuesday's crash in the French Alps would likely lead most airlines and national aviation authorities to follow suit.
"I'm sure, without question, that those security protocols are going to be reviewed, and the exact protocol that was in place at Germanwings is going to be scrutinized very carefully," Cox told CNBC.
Some began doing so Thursday. Canadian Transport Minister Lisa Raitt announced that airlines would immediately enforce the so-called "rule of two" after Air Canada, WestJet Airlines and Air Transat voluntarily adopted the practice Thursday.
The German Aviation Association will consider changing its rules Friday for implementation "as soon as possible," a spokeswoman said. Germanwings' parent company, Lufthansa, and Air Berlin voluntarily adopted the policy Thursday, the airlines said.
Britain's largest airline, easyJet, said it would put the rule into practice Friday. Another major British airline, Virgin Air, also said it would change its rules.
Other airlines that announced new rules Thursday include Norwegian Air Shuttle and Icelandair.