Pair of 747s Collide in Worst Air Disaster of 20th Century
By Patrick Mondout
On March 27, 1977, a terrorist bombing, heavy fog, a slight problem
with the communications system at a critical moment, and an impatient
senior pilot combined to create what remains today the single most deadly
accident in aviation history.
What is remarkable about this accident, aside from the record number of
fatalities, is that neither plane had been scheduled to be at Tenerife's
Los Rodeos airport that day.
Vacation in the Canary Islands
Spain's Canary Islands have long been a destination for European
tourists with its resorts rivaling the best of the Mediterranean. By the
Super70s the islands had also become a destination for Americans wishing
to begin Mediterranean cruises. On the morning of March 27th 1977, two
planes full of such tourists departed for Los Palmas Airport - one of two
major airports in the Canary Islands.
The first plane was a KLM Royal Dutch
Airlines 747 operating as flight
KL4805 on behalf of the Holland International Travel Group. Piloting the
plane was KLM's chief 747 training captain Jacob Veldhuyzen van Zanten,
who also had been featured in KLM advertising - including the in-flight
magazine aboard flight KL4805. He had been with KLM since 1947 and had
trained almost all other KLM 747 pilots and co-pilots. This charter flight
was a rare one for van Zanten as he had been spending much more time
training other pilots than flying.
Captain van Zanten's 747 departed Amsterdam's Schiphol Airport at 9:31
a.m. local time carrying 235 passengers and a crew of 14. The passengers
were mostly young Dutch on vacation and included three babies and 48
children. Also on board were four Germans, two Australians, and four
The second plane was a Pan Am 747
which had departed Los Angeles the night before for the Canary Islands
with a refueling stop in New York. The flight had been delayed an hour and
a half in L.A. and took five hours to make it to New York. A total of 380
passengers were on board and most of them were retirees eager to board the
Royal Cruise Line's ship Golden Odyssey for a 12-day Mediterranean
The plane wasn't just any 747. It was the Clipper Victor - the first
747 to fly passengers (Clipper Young America, the first delivered
to Pan Am, was to make this first flight, but its engines overheated while
taxiing that day and it was replaced). It is the one seen in the news
reels taking off in the first commercial flight of a jumbo jet on January
21, 1970 in New York and landing in London later that day. This day it was
being flown by Captain Victor Grubbs, a 57 year old with over 21,000 hours
of experience as a pilot.
The KLM's uneventful four hour trip took them over Belgium, France, and
Spain and would have had them at Los Palmas airport on time but fate
intervened. At 12:30 p.m. a terrorist's bomb exploded in the passenger
terminal at Los Palmas and a phoned-in threat to detonate another caused
airport officials to close the airport.
The KLM flight was diverted along with several other planes to the
Canary Islands other airport - Los Rodeos - where it landed at 1:10 p.m.
Captain van Zanten was asked to park his plane on an unused parallel
runway next to a Norwegian 737. Shortly
thereafter a DC-8 and 727
A Pan-Am similar to the one
involved in this accident.
Image courtesy of AirNikon.
Find more of his photos at Airliners.net
Hoping the Los Palmas airport would soon reopen, Captain van Zanten
initially asked the passengers to stay on board. After about twenty
minutes with no sign of the airport reopening, he relented and the
passengers were taken to the terminal. At that point one of the
passengers, Robina van Lanschot, who was with the company who had
chartered the flight felt she had seen her passengers through to the
Canaries and called it and day. She decided to stay overnight in nearby
Santa Cruz. This decision certainly saved her life.
Captain van Zanten had more than just inconvenienced passengers to
consider. A number of potentially fatal incidences of crew fatigue in
recent years had stripped KLM pilots of discretion over extending their
crews' continuous hours of service and Captain van Zanten was concerned he
would not be able to make his return flight without breaking those rules
and becoming subject to prosecution back home. After the passengers
departed, he asked for and received permission to refuel his plane for the
trip back home. Unfortunately, this required bringing out a fuel tanker on
the runway - a decision that would prove fateful.
Around this time, the Pan Am 747 was approaching Los Palmas nearly 13
hours after boarding in Los Angeles the previous day. Captain Grubbs,
aware of the closure but also carrying more than enough fuel, had asked
air traffic control (ATC) to allow his
plane to remain in a holding pattern pending the reopening of Los Palmas.
Much to his displeasure, ATC denied the request and he was asked to join
the ever-growing line-up of planes on the unused runway of Los Rodeos in
Captain Grubbs landed his jumbo at 1:45 or about 35 minutes after the
KLM had landed. He too initially asked his passengers to stay on board
though the cabin doors were opened to allow fresh air in.
No Second Bomb
Air traffic control announced no other bombs had been found at Los
Palmas and that the airport was open again. The KLM was still being
refueled but the 737, DC-8 and a 727 were able to maneuver around it and
the Pan Am to make in onto the runway and to take off. ATC then called the
Pan Am and cleared them to line up for a takeoff. The news was greeted
with cheers from the relieved passengers, which now included two
additional Pan Am employees who wanted to take advantage of the flight to
But when it came time for the Pan Am to taxi, it found that it did not
appear to have enough room to get around the KLM and its refueling tanker
as space was limited since Los Rodeos remained virtually unchanged since
the days before large jumbo jets.
Still First Officer Robert Bragg and Flight Engineer George Warns
climbed out of the plane to pace out the amount of space needed to go
around the KLM. Unfortunately, their initial assessment was correct; they
would not be able to leave until after the Dutch jumbo. Meanwhile, the
weather began to deteriorate and fog began to descend on the airport.
Cleared for Takeoff?
By the time the refueling was complete, it was 4:26 p.m. and fog had
reduced visibility at the airport to as little as 300 meters. Two minutes
later the crew asked for and received permission to backtrack down runway
30 (see diagram below) where they would exit on the third taxiway (past
the other planes) and onto runway 12 and then turn at the end of runway 12
back onto runway 30 for takeoff. The communications between the Spanish
ATC (Air Traffic Controller) in the tower and the Dutch crew were in
English and are from the CVR
(Cockpit Voice Recorder):
ATC: "Taxi to the holding position for
Runway 30. Taxi into the runway. Leave the runway third to your
KLM: "Roger, sir. Entering the runway at
this time. And we go off the runway again for the beginning of Runway
ATC: "Correction. Taxi straight ahead, uh,
for the runway. Make, uh, backtrack."
KLM: "Roger, make a backtrack. KL4805 is
now on the runway."
KLM (half a minute later): "You want us to
turn left at taxiway one?"
ATC: "Negative, negative. Taxi straight
ahead, uh, up to the end of the runway. Make backtrack."
KLM: "OK, Sir."
This is the actual KLM 747
(PH-BUF) involved in this accident, seen in
Melbourne, Australia in October, 1973. Click on it
to view a larger version.
Photo by George Canciani. Find
more of his photos at Airliners.net
At this point, the fog was so heavy that the ATC could no longer see
the planes on the runway. First officer Bragg of the Pan Am then confirmed
that they were to enter runway 30 while the KLM was still using it:
Pan Am: "Uh, we were instructed to contact
you and also to taxi down the runway. Is that correct?"
ATC: "Affirmative. Taxi into the runway
and, uh, leave the runway third... third to your left."
Pan Am: "Third to the left. OK."
ATC: "Third one to your left."
According to the Pan Am's CVR, Captain Grubbs was unclear as to what
the Spanish ATC had said: "I think he said first." Bragg
replied: "I'll ask him again." Unfortunately, both planes were
using the same frequency to contact the ATC and before he could ask he
heard the ATC ask the KLM:
ATC: "KL4805, how many taxiway, uh, did you
KLM: "I think we just passed Charlie
[taxiway] four now."
ATC: "OK. At the end of the runway make 180 [turn
completely around] and report, uh, ready for ATC clearance."
Meanwhile, the Pan Am crew were still having difficulty understanding
exactly what to do. First Officer Bragg had a diagram of Los Rodeos
Airport which he was referring to when he said to Captain Grubbs:
"This first [taxiway] is a 90 degree turn." Then he said,
"Must be the third... I'll ask him again." Grubbs then replied
"We could probably go in, it's, uh." Bragg then emphatically
says "You've got to make a 90 degree turn!" Bragg then called
Pan Am: "Would you confirm that you want
the Clipper 1736 to turn left at the third intersection?"
ATC: "The third one, sir. One, two, three - third
The Pan Am crew then began going through the pre-takeoff checklist
still unsure exactly where to get off the runway. "That's two!"
the captain exclaimed.
Warns: "Yeah. That's the 45 [degree
Bragg: "That's this one right here."
Grubbs: "Yeah, I know "
Warns: "Next one is almost a 45."
Grubbs: "But it does, it goes ahead. I
think it's gonna put us on the taxiway."
Warns: "Maybe he counts these as three."
The Pan Am plane has just missed the third taxiway and is continuing
down the runway. (This mistake most likely occurred because the third
taxiway heads back at a 135 degree angle toward the parked aircraft (see
diagram below) instead of at the angle of the forth taxiway and because
the taxiways were not marked. Taking the third taxiway, while accident
investigators concluded it would have avoided the accident, would have
required two very tight 135 degree turns for a big aircraft at an airport
not designed for big aircraft - the pilots may have concluded that the ATC
couldn't have meant for them to take the third taxiway when the next
taxiway was at an easy 45 degree angle.)
Meanwhile, the KLM plane has made it to the end of the runway, turned
around, completed its pre-takeoff checklist, and is ready for takeoff.
Then Captain van Zanten, who desperately wants to get his crew in the air,
does something unexpected. He throttles the engine and the plane starts to
move forward. First Officer Klaus Meurs senses this is wrong and says
"Wait. We don't have clearance!" Van Zanten then presses the
brakes and asks Meurs to get clearance:
KLM: "KL4805 is now ready for takeoff.
We're waiting for our ATC clearance."
ATC: "KL4805. 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."
This clearance is for after they are airborne and is not takeoff
clearance. As First Officer Meurs began to read back the ATC's message,
Van Zanten released his foot from the brakes and began advancing the
throttles for takeoff.
KLM: "Roger, sir, we are cleared to the Papa beacon, Flight
Level 90 until intercepting the 325. We're now at takeoff."
The ATC clearly believed that this meant the KLM was at takeoff
position, awaiting clearance, at the end of the runway:
ATC: "OK. Standby for takeoff. I will call
Pan Am: "We are still taxiing down the runway!"
Tragically, the KLM only heard the "OK" but never heard the
rest of what the ATC said nor the Pan Am's subsequent message (as
confirmed by the CVR tape) as the Pan Am and ATC were speaking at the same
time. The wheels were literally in motion for this accident to occur and
the missed message was the last chance to avoid it. With Captain Van
Zanten and First Officer Meurs busy 20 seconds into takeoff, only KLM
Flight Officer Willem Schreuder listened to the rest of the exchange:
ATC: "Roger. Pan Am 1736, report the runway
Pan Am: "OK. Will report when we are
ATC: "Thank you."
An alarmed Schreuder then asked "Did he not clear the runway
then?" "Oh yes" was van Zanten's reply as the captain
continued his fateful takeoff. The Pan Am, which had missed the third
taxiway and was now approaching the forth when Captain Grubbs said
"Let's get the hell right out of here." "Yeah ... he's
anxious, isn't he?" replied Warns and then added, "After he's
held us up for all this time - now he's in a rush."
1-The planes are parked at the end of runway 12
with the KLM in front of the Pan Am.
2-The KLM has made it to the end of runway 30 and
is ready for takeoff.
3-The Pan Am has passed the first taxiway.
4-The Pan Am has passed the second taxiway.
5-The Pan Am has missed the third taxiway where
it is supposed to exit. The KLM begins to takeoff.
6-The Pan Am tries to get off the runway but is
hit by the KLM.
Diagram of Los Rodeos Airport and accident
Just then, Grubbs saw through the fog the unmistakable image of the
lights on the oncoming 747. "There he is! Look at him! Goddamn ...
that son-of-a-bitch is coming!" Bragg cried out "Get off! Get
off! Get off!" as Grubbs desperately pushed the throttles wide open
in an attempt to get the plane off the runway.
Captain Van Zanten finally saw the Pan Am and tried to pull up. The
plane became airborne but not enough to completely miss the Pan Am. It
sheered off the top of the other 747 then remained airborne another 500
feet before hitting the runway and bursting into flames. All 234
passengers and 14 crew on board the KLM died in the fire.
The Pan Am burst into flames immediately upon impact. Pan Am First
Officer Bragg's first thought was to reach up and switch off the power to
the engines. But he couldn't. The top of the plane right above his head,
where the switch used to be, was gone.
Many of those on the side of the aircraft where it had been hit were
killed instantly or quickly by the resulting fire. Those that were
fortunate enough to escape the flames had to risk serious injury by
jumping 20 or more feet onto wreckage.
Because of the fog, the ATC heard the explosions but could not locate
where they were and thus did not know what had happened. When rescue crews
finally reached the scene, they were able to get 70 survivors to the
hospitals but nine of them eventually died due to their injuries. Almost
half the crew - including all those in the cockpit - survived.
Although it happened in Spanish territory, neither the Americans nor
the Dutch would agree to a Spanish investigation. Thus, the Spanish,
Dutch, Boeing and the Americans investigated the disaster, which remains
the worst aviation accident of all-time with a death toll of 583.
More than 60 investigators were sent to the scene. When KLM officials
first heard of the disaster, they tried to get their best people down to
the scene to investigate. Unaware of the crew list, one of the experts
they tried to reach was Captain van Zanten.
As expected, the Dutch blamed the American pilot for not following
instructions and getting off the runway. The Americans blamed the Spanish
ATC for not giving clear instructions and the KLM pilot for taking off
without clearance and the Spanish cited the KLM pilot's mistake in their
As with most airplane accidents, several seemingly small events
occurred which, had any of them not happened, the tragedy would have been
prevented. For example:
- If the bombing more than 100 miles away at another airport had not
happened or if the phony threat of another bombing had not been made,
those planes never would have been at Los Rodeos.
- If the Pan Am hadn't been 1 1/2 hours late out of Los Angeles, it
would have arrived at Los Palmas before the closure.
- If the Pan Am had been allowed to remain in a holding pattern, it
would not have been at Los Rodeos.
- If the KLM hadn't taken the time to refuel, or if the weather hadn't
deteriorated, the visibility would have been higher when it took off.
- If the Pan Am had been able to make it around the KLM when it was
refueling, it wouldn't have been there when the KLM was taking off.
- If the Pan Am hadn't missed the third taxiway, it would have avoided
- If the Pan Am and ATC hadn't been speaking at the same time, the KLM
would have heard the instruction to wait for clearance.
- If the visibility had been even slightly better, both aircraft may
have had enough time to avoid one another.
Still, the KLM almost missed the Pan Am on the runway.