Things you don't want to hear getting on an airplane

...so I'm walking down the jetway at Houston Hobby airport. One of the pilots is standing at the controls on the phone. He said something about an address--he wasn't talking in a hushed voice or anything--maybe getting directions to El Paso? Anyway, at the same time, I noticed an odd European-sounding siren. He finished his call just in time to get in line in front of me. Honest to goodness, this is the conversation we had. Me: "So what's with the siren?" Pilot: "I was wondering that myself. I think it's the jetway or something." Me: "Is the jetway being pulled over for speeding?" Pilot: (laugh) "I don't know what it is - I've never heard that sound before." Now, I'm not one to get nervous about things that aren't quite right on an airplane. I know the standards are very high for the critical components, and if the pilots aren't worried, I don't need to be worried. I'm just thinking what someone more nervous might think, having a pilot admit "I don't know what that warning signal means". As a consultant, I've been taught that it's OK to say "I don't know" when you don't know, but it should be followed up with "...but I'm going to find out for you." Seems to me most pilots would have some instinct about "things you don't say to passengers". I don't mean to beat up on this pilot, by any means. I set the informal tone of the conversation and he was responding in kind. It's just that his last line triggered the mental cringe that means "don't say that to clients". Out of instinct, I deadpanned it, and thereby lost the flow of a rather nice conversation.