weren't there. >> did you actually visibly see anything other than what the tcas were showing?> negative. it was just a unidentify target. >> reporter:. >> it is a mystery. >> reporter: former ntsb chair robert zumwalt. >> it's important that authorities get on top of this and figure out what is going on so we're not having the spurious or false warnings. >> reporter: the false alarms are playing out at the same airport where january's mid-air collision killed 67. >> 6197, multiple arrivals are reporting tas. not seeing anything out of the windows, though. >> reporter: the jets involved were all embraer air 175 or cj 900 regional ejets. the faa is now investigating. i'm kris van cleave. >>> millions of people are bracing for damages winds and tornadoes as an outbreak of severe thunderstorms tears across the southern u.s. look at this incredible footage. those two private jets you see there have been blown right into that air force transport plane. it happened at alliance airport in fort worth, texas. storms are heading eastward through tuesday night and into wednesday morning.

this is a system called tcas. it stands for traffic. collision avoidance system. it's in every commercial airliner actually mandated after another similar mid-air collision. >> back in. >> the late 70s. and essentially, it tells pilots when a mid-air collision is impending. >> in front of them, it warns them of other airplanes in the area. >> the big mystery now is that pilots were getting. >> these. >> alerts when. >> no other. >> airplane was nearby. according to the federal aviation administration. and now it's opened up this probe into why these alerts could have been going off erroneously. this is a pretty weird and eerie kind of incident because it happened only three miles away on some cases from the site of that mid-air collision over the potomac river. only 31 days prior, the faa says that these mid-air collision warnings were going off in the cockpit of commercial flights repeatedly on flights that were coming in to land on saturday. so we're talking on march 1st. i want you to listen now to some of the audio here of the exchanges between the pilots comi

the traffic collision avoidance systems, known as tcas, alert pilots if another aircraft is nearby or on a collision course with their plane. but no other planes were close. >> there is no known traffic between you and the field. we've had multiple arrivals today. reports tas and ras for unknown targets. use caution. >> experts say it's critical these systems work properly to avoid false alarms. >> it's a potential major distraction of a flight crew at a very critical time of flight, which is landing. so if these are not real warnings and they haven't been, they're distracting and they're dangerous. >> and, david, it is critical that pilots aren't distracted, that they're focused on that runway. so the faa will investigate. david. >> gio benitez back on this for us. gio thank you. overseas tonight the dramatic and deadly scene unfolding in mannheim germany. a driver plowing into pedestrians at a carnival. authorities say at least two people were killed and dozens injured. children were among the victims. the driver is now in custody. tonight, the suspect shot himself in the mouth as p

the system giving these alerts is called tcas. that stands for traffic collision avoidance system. it's required equipment in the cockpits of commercial airliners, which essentially warns pilots when the ingredients for a mid-air collision are brewing. what is especially odd here is that the pilots of multiple flights got these alerts back to back on saturday and in roughly the same spot, which of course led to a lot of chatter with air traffic control. i want you to listen now to the audio from live atc net. >> vacaya 4469. we're covering. >> 4469. >> would you like to go around? >> negative. we got it. 4469 you. >> remember how high. >> that was? >> we're about 1200 feet. there was somebody diving straight onto us. 44. 45, 38. >> preceding arrival. reported a to. two more miles at 1200 feet. it's been happening all morning. >> the faa is clear here in a statement saying there were no airplanes or helicopters nearby. these flights to trigger such an alert. pilots got two types of warnings. one calls out aircraft nearby. one requires the pilot to take immediate action. the faa says

the traffic collision avoidance systems in cockpits known as tcas, are meant to tell pilots if their plane is in danger of colliding with another aircraft. but this morning, no word on why those pilots were receiving false alarms. >> it's a potential major distraction of a flight crew at a very critical time of flight, which is landing. you don't want all of a sudden to be looking for traffic on one side or the other. you want to be concentrating on the runway. so if these are not real warnings and they haven't been, they're distracting and they're dangerous. >> it's especially terrifying because it was at this exact airport where a black hawk helicopter collided with an american airlines plane in january, killing 67 people. the ntsb, still investigating what went wrong. meanwhile, airlines for america, that's the lobbying group for the major u.s. airlines, will testify before a house subcommittee today calling for the permanent suspension of some helicopter routes over at reagan. they also want all military aircraft to broadcast their exact location near airports to avoid a crash li