Q&A discusses how Germanwings pilot was likely locked out of cockpit

Mystery still surrounds the Germanwings jet crash that killed 150 people in the French Alps this week, but investigators seem certain about two things: The jet’s pilot was locked out of the cockpit, and the co-pilot apparently deliberately crashed the plane.

This scenario is possible for two reasons. The first is that European aviation policy had allowed a pilot or co-pilot to be alone in the cockpit if the other leaves to go to the restroom; the second is that cockpit doors are so heavily secured that it is nearly impossible to force them open.

Q. How secure are cockpit doors?

A. Incredibly secure – so secure that they can stand up to gunfire or even small grenades.

After the Sept. 11, 2001, attacks, when hijackers successfully took control of four U.S. airliners, American aviation officials issued new regulations requiring cockpit doors to be reinforced. European air carriers – including Lufthansa, the parent company of Germanwings – followed suit.

Q. How do flight crews normally open a cockpit door?

A. Training materials for Airbus A320 jets – the type that crashed this week – reveal an access procedure that is controlled from inside the cockpit, with only a limited option for outside override.

Since the Sept. 11 attacks, pilots and flight attendants no longer have keys to open the cockpit door, which remains locked during flight, U.S. experts say.

On Airbus jets, access is requested by a keypad outside the cockpit door. According to an Airbus manual and instructional video available online, a three-second buzzer then sounds inside the cockpit, and the pilots at the controls can decide whether to toggle a switch to unlock the door.

Q. Is there any way to open a cockpit door from the outside?

A. If there is no response from the cockpit for a request to open the door, the flight crew can punch in an override code on the keypad, which also sets off a 30-second alert in the cockpit, according to the training video.

If there’s no response from the cockpit by the end of the 30-second alert, the door automatically unlocks for five seconds and can be opened from outside, according to the training video.

But without the emergency access code, “you’re not going to get in,” says Glen Winn, an instructor at the University of Southern California’s school of aviation safety and security. “It’s not going to happen.”

Q. What happens if the pilots in the cockpit do not want someone to open the door?

A. The flight crew inside the cockpit also has an option to deny emergency outside access by hitting a “lock” toggle, according to the Airbus training materials.

If the “lock” toggle is selected, the outside keypad is then disabled for five to 20 minutes or until the pilot decides to unlock the door, according to the training materials.

“If the LOCK position has not been used by the pilot for at least 5 to 20 minutes, the cabin crew is able to request emergency access to open the cockpit door,” the Airbus manual states. “The UNLOCK position overrides and resets any previous selection. In case of an electrical supply failure, the cockpit door is automatically unlocked, but remains closed.”

Investigators have not said whether the pilot locked out of the Germanwings cockpit tried to use a keypad to access the cockpit, or whether the co-pilot toggled the lock switch to override emergency access.

Q. What are the policies for leaving someone alone in the cockpit?

A. At a Thursday news conference, Lufthansa chief executive Carsten Spohr said the airline was not required to bring a flight attendant into the cockpit if a pilot leaves to go to the restroom or get a drink.

But later in the day, the German Aviation Association announced that all German carriers had agreed to new procedures, similar to those in effect in the United States that would require two people in a plane’s cockpit at all times.

The U.S. Federal Aviation Administration issued a statement Thursday explaining its policies. “U.S. airlines have to develop procedures that the FAA approves,” it said. “Those procedures include a requirement that, when one of the pilots exits the cockpit for any reason, another qualified crew member must lock the door and remain on the flight deck until the pilot returns to his or her station.”

“You ask any pilot, they’ll tell you the same thing,” said Winn, the USC instructor. “They don’t leave a person alone in the cockpit. They don’t do it. Nobody does that.”