Tenerife

27 March 1977 · Los Rodeos

You already hold the rule.

Today it is evidence.

583

Neither aircraft should have been there

Las Palmas closed — a bomb in the terminal.

Los Rodeos took the diversions.

A small airport, full of widebodies, at 2,000 ft, in hill fog.

So the runway was the taxiway

The taxiway was blocked by parked aircraft.

Departing aircraft had to backtrack the runway and turn off part way down.

That is why a 747 was on it.

And why the other one was coming the other way

Los Rodeos in plan: the parallel taxiway blocked by parked aircraft at its apron end, and both 747s on the single runway, facing each other.

The phraseology was operating outside the conditions it was designed for.

Four failures

  1. A non-standard progress report
  2. A simultaneous transmission
  3. The reserved word, outside its clearance
  4. A challenge with no phrase available

In that order.

One — the progress report

KLM      We are now at takeoff.

Positioned at the takeoff point?

Or commencing takeoff?

Both are grammatical. Both are things an aircraft can be.

And the reply

TWR      OK. Stand by for takeoff, I will call you.

OK is not a word this language has.

It arrived first — and it arrived as agreement to whatever the other station believed it had said.

Two — stepped on

As the tower transmitted stand by, Pan Am transmitted that they were still on the runway.

The two overlapped.

In the KLM cockpit, a heterodyne where the prohibition should have been.

No transmitting station could know

Week 1, arriving on schedule

Simplex. One carrier, one speaker.

Press to transmit and you cannot hear.

You cannot know you were stepped on. Neither can the other station.

Three — the reserved word

Stand by for takeoff, I will call you.

In fog. Partly obscured. To a crew already committed.

The recommendation that followed: avoid take-off in departure clearances.

That is the direct ancestor of week 4.

Four — the challenge

The flight engineer asked whether Pan Am was clear.

He was answered. He did not ask again.

There was no phrase available for I believe this clearance is not valid.

There still isn’t.

Be careful with this accident

It is the most-told accident in aviation, and the telling has smoothed it.

  • It is one accident. The rule is broader than one accident justifies.
  • The captain has become a character in a story.

What a language course can say

Nothing useful about his personality.

Quite a lot about a system in which the only available word for stop contained the word takeoff.

Read the findings yourself

Two sources, and they disagree:

  • the Spanish investigation’s findings and recommendations
  • the ALPA human factors report

Thursday’s session: map each finding onto the phrase that exists now.

The empty rows are the interesting ones.