Now the latest on the collision at New York's LaGuardia Airport Sunday night that killed two pilots and injured dozens more.

The National Transportation Safety Board said today it was likely a series of failures that led to the accident

when an Air Canada jet struck a fire truck responding to a possible emergency with another plane.

Many questions remain, but we learned today that a runway warning

system failed to sound the alarm moments before the accident and that a fire truck was given

permission to cross the runway less than 30 seconds before they collided. Two controllers were on

duty. For more, we're joined now by our science and aviation correspondent Miles O'Brien. Miles, it's good to see you.

So what more did we learn today from the NTSB and the timeline presented today?

Well, the timing itself, Jeff, is kind of breathtaking. The controllers in the tower there, two of them, were dealing with an emergency on the field.

A 737 United Airlines had fumes in the cabin.

Flight attendants were feeling sick.

And so the crew made the decision to evacuate the passengers off the aircraft.

And that's what precipitated the need to get emergency trucks on the way to this other

aircraft.

The tower team continued pretty much normal operations, allowing the Air Canada aircraft to

continue its approach.

And only 20 seconds before it was to touchdown, gave it clearance to cross the runway.

That is extremely tight and, you know, the controller later said, quoting him now, I messed up.

But it's not so much an individual's responsibility in this case when you look at the whole system and how it failed.

Miles, we have spoken on this program in the past about the concerns over air traffic controller staffing.

And one of the questions that came up during the press conference today was the fact that the air controller in charge was doing the duties of two positions. Here's what the

NTSB chair, Jennifer Homandy said. In this situation for the midnight shift, it is standard

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