What happens if a pilot accidentally locks themselves out during a flight

The locking system in most airliners these days is controlled electronically. There is a keypad near the door where a person can enter a code to gain access to into the flight deck.

In normal operations, the person who wants to go in, keys in the correct code. When done so, a beeper sounds in the cockpit and if there is a camera, it comes on automatically.

The pilots have two options here. Either they can unlock the door or keep it locked. If the pilot keeps his hand off the unlock switch, the door will remain locked. There is no real other possible way to gain access the cockpit given that the door is pretty sturdy and bullet proof.

Flight deck door controls

If an emergency entry is necessary (possible pilot incapacitation), there is a way to do so. There is a special code, different from the normal code. This code, called conveniently the emergency code is a pretty secretive code, known only to three crew members.

The Captain, First officer and the Purser. Entering this code in the keypad activates a beeper in the cockpit. But this time in the door controls of the cockpit, an ‘OPEN’ light flashes. This warns the pilot that the emergency code has been entered and the imminent opening of the door.

To give the pilots the final authority over the door, there is a time gap between the code entry and the opening of the door so that the pilots can lock it using the cockpit door controls, if necessary. If there is no attempt to lock the door, once the pre-set time is reached, the door opens for a few seconds. Just enough for the person to enter the cockpit.

One of the jobs of the purser is to ensure that the pilots are in good health. This is done by periodic calls to the cockpit to ensure, pilots are not incapacitated. If there is no answer from the cockpit when called repeatedly, then the purser can use the emergency code to access the cockpit.

Similarly, the code can be used by the pilots if they get locked out. There should not be a situation where both pilots are out of the cockpit at the same time, because that would be against the regulations. However, if there is a pilot in the cockpit with bad intentions, he can always override the emergency entry code. So, it it not an entirely foolproof system.