Irish airlines Aer Lingus and Ryanair require two people to be in the cockpit at all times for the last number of years, while European regulations do not require two on the flight deck at all times during the flight.

However, the Irish Aviation Authority (IAA) said it approved procedures with Irish airlines a number of years ago to ensure a minimum of two people are in the cockpit at all times.

“The purpose of this is to deal with circumstances where a member of the flight deck crew may become incapacitated or security-related issues,” it said. “The IAA requires and approves procedures with all Irish airlines on this matter.”

The authority said the policy applied to all aircraft where European Aviation Safety Agency (EASA) regulations require a locked cockpit door.

It said although Irish and German aviation safety regulators do meet regularly, there had been no “specific engagement” on this particular procedure.

Aer Lingus said it followed the policy of two people to remain in the flight deck at all times. Its manual states that if one cockpit crew member needs to leave the cockpit, a cabin crew member is required to stay in the cockpit with the door closed until they return.

Ryanair follows a similar policy where, if a pilot needs to visit the bathroom, a cabin crew supervisor is required to stand in the cockpit for the while they are gone. Both airlines said those procedures had been in place since “sealed cockpits came into being”.

Since the crash, several German airlines have implemented the rule requriing two people need to be in the cockpit at all times.

Norwegian Air Shuttle, EasyJet and Air Berlin were some of the carriers that said they would use the policy.

It is already compulsory in the United States and Canada said it would now require it of all its airlines.