Good evening. I'm John Yang. There's been another fatal plane crash, this one in Philadelphia,

even as investigators pieced together evidence from Wednesday's deadly mid-air collision in Washington,

D.C. Last night, a small jet transporting a pediatric patient home to Mexico crashed in northeast

Philadelphia shortly after takeoff. At least seven people died, including the six Mexican citizens on board.

On the ground, homes were set ablaze, and at least 19 people were injured.

It came as investigators continue their search for answers in the collision of a passenger

jet and an Army helicopter near Washington's airport.

That accident claimed 67 lives, the worst U.S. air crash, in at least 15 years.

Randy Babbitt is a former administrator of the Federal Aviation Administration,

and he's also a former commercial pilot.

Mr. Babbitt, the FAA took its first step, its first action yesterday.

They closed off the area around Washington, Reagan National

to low altitude, most low altitude helicopter traffic. What do you think of that?

I think it's a good move. I think it was an important move. There's other ways they can move

the aircraft around, and let's get to the bottom of what happened to this one before we

reinstate that type of routing.

You say reinstate, would you want to see that made permanent or do you think it's just a pause is fine?

Well, I think until they determine the actual, anything we say would be speculation.

But I think the safe thing to do is what they did, and that is just suspend the traffic for now.

No harm done.

It's not like they're grounding them. They can go other ways. It's just they don't want them in that area until we understand have we got the right controls and safety parameters in place to allow traffic to do that.

If the answer is no, then they'll have to design another route.

...