CNN Early Start With John Berman and Christine Romans March 26, 2015 09:36:00
Details. >> exactly. i'm familiar with boeing products. i'm sure it is similar with the airbus. there is a mechanical latch inside the cockpit. if anybody was trying to get in on a nefarious basis, you could simply mechanically lock that door and deny that person entry. there is an electronic way as well of denying into the cockpit. outside of the door more than likely the airbus has a key pad or some code or key to get into. it is probably electronic knowing how airbus is built. so this is highly unlikely. the way it generally works with most airlines that pilot goes out, goes to the lavatory...
Source: archive.org