through a pilot making a mistake. but remember, there is avionics on board, particularly one called collision avoidance assistance. >> reporter: the faa says it has taken steps to prevent any similar occurrences in the future but they didn't say what those steps were. these air traffic controllers are trained in real-time. we do know an instructor was there at the moment this incident happened ready to step in, if needed. but the trainee realized the mistake immediately and corrected the problem immediately. we do know that the flights continued safely to their destinations. still, when you hear this sort of thing, it's very disturbing. >> it's horrifying. four in one month. is there any repurchaercussions? is. >> any accountability behind the scenes? >> there was a controller caught sleeping and that controller in