so once that transponder is turned off those airplanes can in effect, be very hard to see on civilian ray or daughters. military radars, a little bit different. jenna: so you re saying that a fire just to tie this in, inside the cockpit or somewhere deep inside the plane could have affected, for example, the transponder? when we say the transponder s been turned off, that could have been a fire? yeah. i think a more accurate way an investigator would be to say that the transpond orer stopped working. the airplanes are designed to deal with fires that happen in the engines and so we have fire detection systems and extinguishing systems for that. probably one of the biggest dangers and one of the ones we saw in the crash of the swiss air flight by halifax, nova scotia is there s lots of wire bundles that go above, you know in the ceiling of the airplane and underneath the floor of the airplane. so as you re sitting in the airplane there s actual wire bundles going beneath your feet and