I have always placed my ht's in my carry-on bags, and only had to explain a few times, usually at smaller airports. I go thru ORD, three to four times a month and only once did I have a problem. It was completely my fault. I got off the bus, and realized that my fire pager was on my belt, I threw it in my carry on. It makes a continous tone when the battery goes down, and by the time I got to security, it was blaring away. The noise caused a bit off a stir. Luckily, I was with some other firefighters, and all my ham gear was eaisly identifiable. However, I did miss my flight cause of the 'interviews'. United, did put my on the next flight, with no additional expense, when I explained to the ticket agent(very courteous) what happened.