Great demo by the F-27. I was shooting the breeze with one of the F/O's on that demo one day. He told me the PNF would switch #2 VHF to an unused freq and begin a 10 count. The #2 antenna was on the belly below the cargo door and when they began to get feedback on the freq they knew they were within 2 feet of the runway. I asked what happened if they lost the feedback and he replied " It means the Captain has gotten too low and scraped the antenna off." I think he was serious.