debris field and surveying it with sonar, getting a good map of it they will do that but once they start diving weather conditions will definitely be a factor. >> what can the wreckage tell us about flight 8501's final moments as you piece this together? >> well i'm not an expert in that field, ed but i think if they have a large varied spencer hadleyo it would tell me they . >> if they have a large shadow it tells me they came down in a relatively large piece of airplane. the aviation experts are the guys to go to for that. if it is a large piece of debris and the fusel lodge is in fact it will make the recovery efforts for the black boxes and the victims probably a lot easier to accomplish. >> okay there's debris so the black boxes are somewhere. what in your professional experience of the recovery