NARRATOR: Joining the investigation
is Bob Benzon of the US National Transportation Safety Board.
ROBERT BENZON: Because the aircraft was manufactured
of the United States, our role was
really to assist the Swiss government
in determining what happened.
It looked to us like the aircraft had struck the trees
in a bit of a level altitude, although parts
of the right wing had been sheared off by the trees.
And that caused a more lift to occur
on the left side of the aircraft,
causing the aircraft to roll.
So the eventual impact was nearly inverted.
So they were cleared for runway 14.
It looks like they're on the right heading.
They're way too low.
It's like they don't even know the hill's there.
NARRATOR: Investigators begin with the flight data,
looking for any sign of a mechanical problem on board.
Thrust is good.
Pitch and roll, fine.
Flaps good.
INVESTIGATOR 2: Yup.
INVESTIGATOR 1: No stabilization problems.
Everything seems normal from a mechanical standpoint.
Even the glide is smooth and straight.
It's just all over 1,000 feet too low.
OK.
CO-PILOT: Can we do a radio approach?
PILOT: Yes.
They're at just over 4,000 feet right here, which
is well below the glide slope.
OK, so.
But they need to level off to capture the glide.
But they kept descending.
On 1.
Let's do it on 1.
CO-PILOT: Radio one confirmed.
NARRATOR: ILS transmitters send radio signals
to two navigational receivers in the cockpit.
Nav Radio 1 and Nav Radio 2.
The pilots can use either one to guide the plane.
Investigators now know the crew selected Nav Radio 1.
But they're still hoping to discover
something about the unusually low glide slope
and about the GPWS.
AIR TRAFFIC CONTROLLER: Alitalia 404, reduce to 160 knots.
PILOT: Reducing 160.
Capture glide path, so we're on the beam.
Would you stop it there?
On the beam?
They're well below the glide slope there.
They are more than 1,000 feet below it.
So why is the captain saying then that he captured it?
NARRATOR: What they're hearing from the cockpit
only deepens the mystery.
INVESTIGATOR 2: Did they misread the altimeter
and the glide slope?
I mean, that doesn't seem possible.
Let's keep listening for the GPWS.
OK.
CO-PILOT: Flaps 25.
PILOT: Flaps 25.
The outer marker check is at 1,250 feet, almost four miles.
Didn't we pass it?
Didn't we pass the outer marker?
No.
No, it hasn't changed yet.
Something in that cockpit is confusing these pilots.
AIR TRAFFIC CONTROLLER: Alitalia 404, speed is convenient.
Contact tower 118.1.
118.1.
Goodbye.
That doesn't make sense to me.
Go around.
PILOT: No, no, no.
Hold the glide.
The CVR had the first officer attempting to go around
and then being countermanded by the captain.
There was a lot of confusion there.
PILOT: Can you hold it?
CO-PILOT: Yes sir.
NARRATOR: Investigators are stunned,
both by what they've heard and by what they haven't heard.
No ground proximity warnings at all.
And the captain called off a go around.
NARRATOR: They now face more questions than ever.