New reports of another terrifying near collision in the sky.
The FAA is investigating how two united airlines flights with hundreds of passengers on board came just seconds away from slamming into each other.
The planes were less than a mile apart above Houston. This is at least the fourth time in just the past month that two planes almost collided mid-air.
It's a troubling trend as millions of Americans head to the airport tonight. Memorial day travel is expected to reach a record high this weekend.
But how does a near mid-air collision happen?
Tom Foreman steps inside the CNN virtual room to see exactly how close Â the planes in Houston came to a mid-air collision.