NTSB warns of near airplane collisions

On a clear day in Los Angeles last August there was a close call that almost ended in disaster. Tuesday, the NTSB released animation and radio transmissions, revealing a Southwest 737 cleared for takeoff on the very runway that an Asiana 747 arriving from South Korea had been cleared to land.

The planes got within 12 seconds and 145 feet of each other, before the Asiana pilot aborted his landing, and a third pilot jumped on the radio. At the last moment, the controller realized his mistake and ordered Southwest to abort take-off.

"If the weather had been less than perfect or had it been nighttime, we may have had a very different outcome," says NTSB investigator Sandy Rowlett.

This event is eerily similar to a 1991 incident when a US Air jet was cleared to land on the same LAX runway that a commuter jet was using for take-off. Those planes collided, killing 33 people.

The NTSB calls the close calls "runway incursions,” and it's concerned that many are going unreported.  While the control tower told the Federal Aviation Administration of the incident in August, the NTSB learned of it from the Southwest crew that almost had that Asiana 747 land on top of them.

While the number of runway incursions has dropped almost 25 percent from its peak in 2000, it's up 62 percent since 1994, according to the NTSB. But the FAA says for major airlines, the nation's taxiways have never been safer.

"Down 50 percent over the last four years," says FAA administrator Marion C. Blakey. "That's the record in terms of serious runway incursions."

The FAA is installing new lighting and radar systems designed to warn pilots and controllers if planes are about to collide. And NASA is also developing new 3-D displays to help pilots see at night and in poor weather.

But last August, with 300 lives at stake, it wasn't technology, but a pilot's quick action that avoided disaster. On the nation's congested taxiways, there is heightened concern for the margin of safety.