airline pilot and aviation safety specialist with safety operating systems. and sean pernicky, accident investigator for flight 5191. so, gentlemen, sean, i'm giving you the first one. this is a question for michael. has anyone flown the route back over malaysia to see if there is any ground wreckage, maybe other data is incorrect? we don't know the answer. but do you think that they should do that? fly back over the route, retrace? >> yeah, it's actually a pretty straight forward question. that would be someplace that you would go back to your last known points, points in time and place. >> what would they see? >> basically what you're looking for is obviously the wreckage, but in areas for example on land where it's heavy forestation or