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.
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.
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.
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.
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.
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?
