at a huge bone yard in california s mojave desert. here s what he discovered about the doors and what the captain was up against. reporter: stores airplanes no longer being used here but this boeing 737 was flown after 9/11 so it has a reinforced cockpit door. we want to give you a close up look at how it works. the 737 was moth balled less than a year ago. the locking system on these reinforced doors is very similar to the locking system you would have in an airbus a 320 that crashed in france. he s the director of southern california aviation. what is this door made of? this reinforcement? this is an inch and a half thick of kevlar with some steel. it s a kevlar door. reporter: unlike the airbus this is a key lock? this is a key override system. reporter: but it has what the airbus has. a numbering system. what is that for? a key pad to punch in the