electric. so it has triple redundancy. if one system fails, another works and another works. so the notion that all failed at the same time is hard to believe. third, the cockpit door is locked. 3w both pilots are highly experienced. and richard flew with the co-pilot who loved aviation. so it's hard to believe that they were in on this. and i think we're still searching for some physical evidence of what happened to this plane. >> richard quest, you spoke to one of the pilots, the co-pilot of this 777. how -- real spoke our viewers a picture of the transponder. how difficult is to turn off one of the transponders? >> i've been asking pilots all day about that very question. it's relatively easy. and indeed the sort of -- you'll often hear pilots being told to switch on their transponder