LONDON >> Airlines and officials around the world on Thursday began requiring two crew members to always be present in the cockpit, after details emerged that the co-pilot of Germanwings Flight 9525 had apparently locked himself in the cockpit and deliberated crashed the plane into the mountains below.

Leading European budget airlines Norwegian Air Shuttle and EasyJet, along with Air Canada, say they will now require a minimum of two crew members in the cockpit while a plane is in the air.

A group representing Germany’s biggest airlines, including Lufthansa and Air Berlin, say they plan similar rules. German Aviation Association spokeswoman Christine Kolmar said the plan will be presented to German aviation authorities on Friday and the airlines will implement it “as soon as possible.”

Canada’s government also issued an immediate order requiring two crew members to be in the flight deck at all times. Transport Minister Lisa Raitt said the government is reviewing all policies and procedures and is watching the situation in Europe closely.

Following the Sept. 11, 2001 terrorist attacks, U.S. airlines revamped their policies regarding staffing in the cockpit. But the procedure is not standard in Europe or Canada.

According to U.S. rules, whenever the cockpit door is open, flight attendants create a barrier between the cockpit and passengers. Typically, that is done with a beverage cart but some jets are outfitted with a mesh wire barricade. If a pilot leaves to use the bathroom, one of the flight attendants takes his or her seat in the cockpit.

Some European airlines, like Finnair and Czech national airline CSA, operate under similar procedures. But many did not prior to Tuesday’s Germanwings crash, which killed all 150 people aboard.

European investigators said Germanwings co-pilot Andreas Lubitz barricaded himself inside the cockpit of the Airbus jetliner and deliberately crashed it into a mountainside, killing all 150 passengers and crew aboard.

Norwegian spokeswoman Charlotte Holmbergh-Jacobsson said the new rules will be adopted “as soon as possible” on all commercial flights globally. She said that the airline’s security department had been thinking about the measure “for a while, and today decided on it.”

Air Canada, Canada’s largest airline, said it will implement its change “without delay” the policy change. The country’s other airlines, Westjet and Transat, also said it would make the change immediately. Porter airlines said it policy has always been to have at least two crew in the flight deck at all times.

EasyJet said its new rules will take effect Friday.