takes three days to find the bulk of the wreckage. after finding 97% of the plane, crash experts reassemble it in a long island hangar. >> you can place pieces of the aircraft back together again so you can see how they relate to each other and the impact related. >> is that kind of reconstruction still necessary? >> well, there is obviously debate about that. >> reporter: that is because data recorders like the one on flight 370 are now more sophisticated. the older model on flight 800 could record only 18 indicators. investigators needed to investigate because the data gave a partial view of what happened on board at the time of the crash. >> essentially, speed, altitude, heading. it was not that helpful in the determining what the probable cause was. >> reporter: the missing data recorder from flight 370 captures 82 separate indicators,