that. we're about to go so slow we're going to fall out of the air. he's on the razor's edge of either toppling over the top too fast or too slow we're going to collapse down to the ground. let me show you what happens if you go over the top now and decide to descend at that rate. which you couldn't do, 40,000 feet, mitchell, push us over the top. >> let's do it. >> reporter: what you're going to find out there's going to be a tremendous g force that starts to build up. the alarms, the sink rate. what's that telling us? >> telling us we're sinking too fast and going too fast. you can hear the air frame. this literally would be where stuff is starting to fall off the airplane. the airplane would begin to break apart in the air. pieces literally coming off. and if you can level off which mitchell will try to do, you pass such a level of g force you can't imagine whether it's even survivable in the back or whether anybody would be conscious. that's why we say when you try to run this through this