The Deadliest Plane Crash

The Final Eight Minutes

The investigation into the myriad causes of the disaster at Tenerife's airport on March 27, 1977 was one of the largest in aviation history, involving more than 70 officials from Spain, the Netherlands, and the United States. Because the actions of both the flight crews of the two aircraft involved and Los Rodeos Airport's air traffic controllers so directly contributed to the disaster, the log of conversations between the two planes and the tower in the minutes leading up to the collision was investigators' key tool for ultimately piecing together the events. Below, examine an interactive diagram of the events of that afternoon and read an annotated transcript of the two planes' communications with the tower. Then decide for yourself just what caused the worst plane crash of all time.—Lexi Krock

Note: Throughout this feature, click on highlighted terms for a brief explanation.

The Final Minutes

Cockpit Recordings

Key to communications

APP—Air traffic control tower at Los Rodeos Airport
PA RT—Pan Am aircraft radio transmission
PA 1—Victor Grubbs, Pan Am Captain
PA 2—Robert Bragg, Pan Am First Officer
PA 3—George Warns, Pan Am Flight Engineer
PA 4—Unidentified fourth person in Pan Am cockpit, likely one of two Pan Am employees who boarded in Tenerife and were sitting in the cockpit jumpseats
KLM RT—KLM aircraft radio transmission
KLM 1—Veldhuyzen (Jacob) van Zanten, KLM Captain
KLM 2—Klaas Meurs, KLM First Officer
KLM 3—Willem Schreuder, KLM Flight Engineer
?—Unidentified

Note: The transcript below comes from the official Spanish accident report (see www.project-tenerife.com/engels/PDF/Tenerife.pdf) and has been slightly modified for clarity and ease of reading. Paragraphs preceding sections of the transcript, and also explanatory text attached to linked words or phrases, are NOVA annotations.

At 4:58 p.m. on March 27, 1977, when this transcript begins, the KLM and Pan Am 747s are both in queue to taxi down the runway and turn around for takeoff. The KLM aircraft is ahead of the Pan Am aircraft (see number 1 on the diagram above). Some back-and-forth occurs initially about what Air Traffic Control considers the best way to get the KLM plane into position for takeoff, but ultimately the controllers decide to send it taxiing straight down the runway. This portion of the transcript comes from the KLM cockpit voice recorder.

1658:14.8

KLM RT

Approach KLM 4805 on the ground in Tenerife.

1658:21.5

APP

KLM—ah—4805, roger.

1658:25.7

KLM RT

We require backtrack on 12 for takeoff Runway 30.

1658:30.4

APP

Okay, 4805 ... taxi ... to the holding position Runway 30.

Taxi into the runway and—ah—leave runway (third) to your left.

1658:47.4

KLM RT

Roger, sir, (entering) the runway at this time and the first (taxiway) we, we go off the runway again for the beginning of Runway 30.

1658:55.3

APP

Okay, KLM 80—ah—correction, 4805, taxi straight ahead—ah—for the runway and—ah—make—ah—backtrack.

1659:04.5

KLM RT

Roger, make a backtrack.

1659:10.0

KLM RT

KLM 4805 is now on the runway.

1659:15.9

APP

4805, roger.

1659:28.4

KLM RT

Approach, you want us to turn left at Charlie 1, taxiway Charlie 1?

1659:32.2

APP

Negative, negative, taxi straight ahead—ah—up to the end of the runway and make backtrack.

1659:39.9

KLM RT

Okay, sir.

With the KLM aircraft now taxiing down Runway 12, Air Traffic Control turns its attention to Pan Am 1736. The controllers instruct the plane to travel down the runway and then exit it using one of the transverse taxiways. This would clear the way for the KLM plane to take off. This portion of the transcript comes from the Pan Am cockpit voice recorder.

1701:57.0

PA RT

Tenerife, the Clipper 1736.

1702:01.8

APP

Clipper 1736, Tenerife.

1702:03.6

PA RT

Ah—we were instructed to contact you and also to taxi down the runway, is that correct?

1702:08.4

APP

Affirmative, taxi into the runway and—ah—leave the runway third, third to your left, [background conversation in the tower].

1702:16.4

PA RT

Third to the left, okay.

1702:18.4

PA 3

Third, he said.

 

PA?

Three.

1702:20.6

APP

[Th]ird one to your left.

1702:21.9

PA 1

I think he said first.

1702:26.4

PA 2

I'll ask him again.

1702:32.2

PA 2

Left turn.

1702:33.1

PA 1

I don't think they have takeoff minimums anywhere right now.

1702:39.2

PA 1

What really happened over there today?

1702:41.6

PA 4

They put a bomb (in) the terminal, sir, right where the check-in counters are.

1702:46.6

PA 1

Well, we asked them if we could hold and—uh—I guess you got the word, we landed here...

1702:49.8

APP

KLM 4805 how many taxiway—ah—did you pass?

1702:55.6

KLM RT

I think we just passed Charlie 4 now.

1702:59.9

APP

Okay ... at the end of the runway make 180 [degree turn] and report—ah—ready—ah—for ATC clearance. [background conversation in tower]

1703:09.3

PA 2

The first one is a 90-degree turn.

1703:11.0

PA 1

Yeah, okay.

1703:12.1

PA 2

Must be the third ... I'll ask him again.

1703:14.2

PA 1

Okay.

1703:16.6

PA 1

We could probably go in, it's ah...

1703:19.1

PA 2

You gotta make a 90-degree turn.

1703:21.6

PA 1

Yeah, uh.

1703:21.6

PA 2

Ninety-degree turn to get around this ... this one down here, it's a 45.

1703:29.3

PA RT

Would you confirm that you want the Clipper 1736 to turn left at the third intersection? ["third" drawn out and emphasized]

1703:35.1

PA 1

One, two.

1703:36.4

APP

The third one, sir, one, two, three, third, third one.

1703:38.3

PA ?

One two (four).

1703:39.0

1703:39.2

PA 1

PA RT

Good.

Very good, thank you.

1703:40.1

PA 1

That's what we need right, the third one.

1703:42.9

PA 3

Uno, dos, tres.

1703:44.0

PA 1

Uno, dos, tres.

1703:44.9

PA 3

Tres—uh—si.

1703:46.5

PA 1

Right.

1703:47.6

PA 3

We'll make it yet.

1703:47.6

APP

...er 7136 [sic] report leaving the runway.

1703:49.1

PA 2

Wing flaps?

1703:50.2

PA 1

Ten, indicate 10, leading edge lights are green.

1703:54.1

PA ?

Get that.

1703:55.0

PA RT

Clipper 1736.

1703:56.5

PA 2

Yaw damp and instrument?

1703:58.6

PA 1

Ah—Bob, we'll get a left one... 

1703:59.3

PA 2

I got a left.

1704:00.6

PA 1

Did you?

1704.00.9

PA 2

And—ah—need a right.

1704:02.6

PA 1

I'll give you a little... 

1704:03.8

PA 2

Put a little aileron in this thing.

1704:05.0

PA 1

Okay, here's a left and I'll give you a right one right here.

1704:09.7

PA 1

Okay, right turn right and left yaw.

1704:11.4

PA 2

Left yaw checks.

1704:12.4

PA 1

Okay, here's the rudders.

1704:13.6

PA 1

Here's two left, center, two right center.

1704:17.8

PA 2

Checks.

1704:19.2

PA 2

Controls.

1704:19.6

PA 1

Haven't seen any yet!

1704:20.3

PA 2

I haven't either.

1704:21.7

PA 1

They're free, the indicators are checked.

1704:24.6

PA 2

There's one.

1704:25.8

PA 1

There's one.

1704:26.4

PA 1

That's the 90-degree.

1704:28.5

PA ?

Okay.

1704:34.5

PA 2

Weight and balance finals?

1704:37.7


[Sounds similar to stabilizer trim]

1704:37.2

PA 1

We were gonna put that on four and a half.

1704:39.8

PA 3

We got four and a half and we weigh 534. [sound of stabilizer trim]

1704:44.6

PA 2

Four and a half on the right.

1704:46.8

PA 2

Engineer's taxi check.

1704:48.4

PA 3

Taxi check is complete.

1704:50.5

PA 2

Takeoff and departure briefing?

1704:52.1

PA 1

Okay, it'll be standard. We gonna go straight out there till we get 3,500 feet, then we're gonna make that reversal and go back out to ... 14.

1704:58.2

APP

[KLM] 8705 [sic] and Clipper 1736, for your information, the centerline lighting is out of service. [APP transmission is readable but slightly broken]

1705:05.8

KLM RT

I copied that.

1705:07.7

PA RT

Clipper 1736.

1705:09.6

PA 1

We got centerline markings (only) [could be "don't we"] they count the same thing as ... we need 800 meters if you don't have that centerline ... I read that on the back (of this) just a while ago.

1705:22.0

PA 1

That's two.

1705:23.5

PA 3

Yeah, that's 45 [degrees] there.

1705:25.7

PA 1

Yeah.

1705:26.5

PA 2

That's this one right here.

1705:27.2

PA 1

[Yeah], I know.

1705:28.1

PA 3

Okay.

1705:28.5

PA 3

Next one is almost a 45, huh, yeah.

1705:30.6

PA 1

But it goes...

1705:32.4

PA 1

Yeah, but it goes ... ahead, I think (it's) gonna put us on (the) taxiway.

1705:35.9

PA 3

Yeah, just a little bit, yeah.

1705:39.8

PA ?

Okay, for sure.

1705:40.0

PA 2

Maybe he, maybe he counts these (are) three.

1705:40.0

PA ?

Huh.

1705:44.8

PA ?

I like this.

In the final minute before the collision, key misunderstandings occur among all the parties involved. And in the end, the KLM pilot initiates takeoff, even though Air Traffic Control has not issued the proper clearance.

1705:41.5

KLM 2

Wait a minute, we don't have an ATC clearance.


KLM 1

No, I know that. Go ahead, ask.

1705:44.6

KLM RT

Uh, the KLM 4805 is now ready for takeoff and we're waiting for our ATC clearance.

1705:53.4

APP

KLM 8705 [sic] uh you are cleared to the Papa beacon. Climb to and maintain flight level 90 ... right turn after takeoff proceed with heading 040 until intercepting the 325 radial from Las Palmas VOR.

1706:09.6

KLM RT

Ah, roger, sir, we're cleared to the Papa beacon flight level 90, right turn out 040 until intercepting the 325, and we're now (at takeoff).

1706:11.08


[Brakes of KLM 4805 are released.]

1706:12.25

KLM 1

Let's go ... check thrust.

1706:14.00

[Sound of engines starting to accelerate.]

1706:18.19

APP

Okay.

Why Air Traffic Control would say "okay" after KLM has said it is taking off is unknown. Perhaps, the official investigation noted, the controller thought that KLM meant "we're now at takeoff position." But the problem is compounded in the moments immediately following, when both Air Traffic Control and Pan Am RT speak simultaneously. This causes a shrill noise in the KLM cockpit that lasts for almost four seconds and makes the following three communications hard to hear in the KLM cockpit:

1706:20.08

APP

Stand by for takeoff ... I will call you.

PA1

No, uh.


PA RT

And we are still taxiing down the runway, the Clipper 1736.

The following messages are audible in the KLM cockpit, causing the KLM flight engineer, even as the KLM plane has begun rolling down the runway, to question the pilot:

1706:25.47

APP

Ah—Papa Alpha 1736 report runway clear.

1706:25.59

PA RT

Okay, we'll report when we're clear.

1706:31.69

APP

Thank you.

1706:32.43

KLM 3

Is he not clear, then?

1706:34.10

KLM 1

What do you say?

1706:34.15

PA ?

Yup.

1706:34.70

KLM 3

Is he not clear, that Pan American?

1706:35.70

KLM 1

Oh, yes. [emphatically]

Perhaps because of the KLM pilot's very senior position, neither the copilot nor flight engineer questions the pilot again, and the impact occurs about 13 seconds later. Based on the Pan Am cockpit voice recording, investigators determined that the Pan Am flight crew saw the KLM coming at them out of the fog about nine seconds before impact. The Pan Am captain says "There he is ... look at him! Goddamn, that [expletive deleted] is coming!" and his copilot yells "Get off! Get off! Get off!" The Pan Am pilot guns the engines but it's too late. At 1706:47.44, the KLM pilot screams, and the collision occurs.

Enlarge this image
Tenerife crash

By the time either flight crew saw the other plane in the fog, it was too late to avert the disaster, which arose out of a series of miscommunications among both flight crews and the control tower.









Enlarge this image
Tenerife crash

One of many what-if questions that students of the tragedy ask is: Could the KLM 747 have cleared the taxiing Pan Am plane if the KLM's pilot hadn't insisted on refueling his aircraft before leaving Tenerife, thereby greatly increasing its weight?





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