well. les, you've been flying for nearly 30 years. as you look at this, given what we know, the transponder was off, as we said, that went off at two minutes after the last communication at 1:19. 1:21 the transponder goes off. we know the 1:37 a.m. acars system that was supposed to send a message did not send a message so that acars system, last one was from 1:07. you talk about this compartment below the cockpit where the system is located and we've got this tour of it here. can you talk to us about what you think was most likely to have happened here given the complexity of this whole system? >> well, that's a good point, it is a complex system. as pilots trained on this airplane, we don't know -- we know what the system does for us but to know every detail down there, i mean i'm considered an expert.