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.

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 cruise.

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.

Unscheduled Landing

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 joined them.

Pan-Am 747 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.

Overtime

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 Tenerife.

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 Los Palmas.

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 left."

KLM: "Roger, sir. Entering the runway at this time. And we go off the runway again for the beginning of Runway 30."

ATC: "Correction. Taxi straight ahead, uh, for the runway. Make, uh, backtrack."

KLM: "Roger, make a backtrack. KL4805 is now on the runway."

ATC: "Roger."

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."

KLM Boeing 747-206B 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 pass?"

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 ATC:

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 one."

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 taxiway] there."

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 you."

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 clear."

Pan Am: "OK. Will report when we are clear."

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

"Get off!"

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.

Investigation(s)

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 report.

What If?

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 a collision.
• 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.

KLM/Pan Am at a Glance
Airline	Pan Am and KLM
Date	March 22, 1977, 4:28 p.m. (local time)
Flight number	Pan Am 1736, KLM 4805
Registration Number	Pan Am N736PA, KLM PH-BUF
Crew Fatalities	Pan Am: 9 of 16; KLM: all 14
Passenger Fatalities	Pan Am: 326 of 380; KLM: all 234
Total Fatalities	Pan Am: 335 of 396; KLM: all 248

Air Safety References:
Bartelski, Jan. Disasters in the Air: Mysterious Air Disasters Explained. Airlife Publishing: England, 2001.
Beaty, David. The Naked Pilot: The Human Factor in Aircraft Accidents. Airlife Publishing: England, 1996.
Cushing, Steven. Fatal Words: Communication Clashes and Aircraft Crashes University of Chicago Press: Chicago, 1997.
Faith, Nicholas. Black Box: The Air-Crash Detectives-Why Air Safety Is No Accident. Motorbooks International, 1997.
Gero, David. Aviation Disasters: The World's Major Civil Airliner Crashes Since 1950. Sutton, 2003.
Job, Macarthur. Air Disaster (Volume 1). Aerospace Publications: Fyshwick, Australia, 1995.
Job, Macarthur. Air Disaster (Volume 2). Aerospace Publications: Fyshwick, Australia, 1996.
Job, Macarthur. Air Disaster (Volume 3). Aerospace Publications: Fyshwick, Australia, 1999.
Krause, Shari Stamford. Aircraft Safety: Accident Investigations, Analyses & Applications. McGraw Hill, New York, 1996.
Macpherson, Malcolm. The Black Box : All-New Cockpit Voice Recorder Accounts Of In-flight Accidents. New York: William Morrow, 1998.
Macpherson, Malcolm. On a Wing and a Prayer: Interviews with Airline Disaster Survivors. Perennial, 2002.
Owen, David. Air Accident Investigation, 2nd Edition. Motorbooks International, 2002.
Stewart, Stanley. Emergency! - Crisis on the Flight Deck, 2nd Edition. Airlife Publishing, England, 2003.
Walters, James M. Aircraft Accident Analysis: Final Reports. McGraw-Hill Professional, 2000.
Wells, Alexander T. Commercial Aviation Safety, 3rd Edition. McGraw-Hill Professional, 2001.

Share Your Memories!

What do you remember about this crash? Were you a witness? Have you any compelling stories to share? Share your stories with the world! (We print the best stories right here!)

		Your Memories Shared!

"You may note that four Americans died who were passengers of the KLM plane. I had got to know the Gillis family fairly well as I had befriended there son Jim, who was not a passenger on the plane. Mr. and Mrs. Gillis and their son Jim came to The Netherlands because Mr. Gillis was transferred by Xerox in Rochester to Xerox in Venray, The Netherlands. I was an employee of Xerox and became good friends with Jim as his father had organized a job for him. Jim, who was about 20 at the time, had left a girlfriend and a little baby behind in the states (surname is Twist) who eventually came to The Netherlands to visit. Ms. Twist and baby were to stay for a couple of weeks and during this time Jim and his ex seemed to be getting everything back on track. Mr. and Mrs. Gillis took their daughter-in-law-to-be and granddaughter for a brief stay in the Canary Islands. Jim couldn’t go because things were busy at Xerox. The rest is history. I informed Jim of the disaster and chaperoned him to the airport back to the U.S. a few days later never to hear from him again. I was wondering what I needed to do to try and contact him. I guess I am unsure whether he would like to hear from me because he may well associate his memory of me with everything else.I left Holland in 1981 and moved to Australia and at this point it has become a mission for me to try and locate him. Do you have any ideas?" --John Ruyl (alexandjohn at bigpond dotcom dot au)

"I lost my grandmother & great aunt & great uncle in this crash. It was a Sunday and I lived in Detroit. My grandmother was from Canada & my anut & uncle were from CA. All were going on the cruise as mentioned. After hearing of the crash we went to my grandmother's house in Windsor, Ontario and saw a telegram from Western Union posted to her front door. It was from Pan Am, confirming that they had, indeed, checked in for their flight....My grandmother and aunt were never identified; my uncle was identified & had a funeral service in CA with the rest of the deceased. They are buried in a mass grave site in Westminister, CA." --Robyn Caza-Vanderbrook

"Iam Ingrid de la Roy from the Netherlands, and I lost my both parents (Wiel and Annie de la Roy, 39/37 years old) at that crash. It hurts to see all this again, but I am happy too that like this way I become to know everything about what happend. I have maked a own map off all this, for my brothers too. So if you know or have (video-mpeg) material about this, please send this to us." --Ingrid de la Roy (gerard.ingrid at home.nl)

"I was 13-years old at that time. My family and myself lived in Las Palmas at that time. It was Sunday afternoon and I watched TV. First I remember the news about the bomb at the airport. The bomb was placed by Antonio Cubillo’s terrorist, it was an organization based in Alger. They fought for the independence of Canary Island. After the news the TV program continue normally, but suddenly they interrupted the program. The said it have happened a serious accident in Tenerife (I don’t remember if they mentioned it was an airplane accident?), but they asked all hospital staff (doctors, nurses, paramedics) to interrupt their weekend leave, holidays and return to their positions at the hospitals immediately. I realize then that something really serious have happened, because they said at the TV this several times. Some days later I remember that they interviewed the Chief Doctor of Tenerife University Hospital. The Chief doctor said, "We have trained for this kind of disasters, but we coulnd’t believe that we really will get someday in one shot several hundreds of victims." This is what I remember from this accident, I don’t remember any pictures from TV or newspapers. For sure this Sunday afternoon in 1977 I remember forever." --PK

"I was enroute to Amsterdam at the time of the crash in the Canary Islands. I also was on a KLM 747-Flight 644 from New York's Kennedy Airport. I had no idea that anything had happened until I arrived in Amsterdam and that is when I heard about the accident. My husband was frantic because my flight was 30 minutes late arriving. It was just a terrible accident, and my loved ones in the states were sure relieved when I called them to let them know that I had arrived safely." --Anonymous

"I was on holiday with my family on Tenerife when this accident happened. I was nine years old. I clearly remember the shocked, dazed attitude of the adults around me when we heard the news. I must confess to be being pretty ambivalent about it at the time. I believe their is still evidence of some wreckage at that particular airport (now rarely used) to this day. [Editor's note: It was in 1996 when one of the crew went back to Tenerife for a documentary I saw in 1997.]" --Stephen Curry

"This accident occurred when I was in the sixth grade. My Aunt was a travel agent at the time and had recently visited the Canary Islands herself. She had dear friends on this flight who perished. I remember this event as the first disaster that seemed real to me. I remember writing a current event report on it in school. Seems small now in light of 9/11." --Anonymous

"My Grandfather, John Cooper, was was one of the survivors of the Pan Am / KLM air disaster. He was employed as a Pan Am engineer and was 'hitching a lift' aboard the flight. When flying he always carried a pocket shoe shine box as good luck, but ironically on this day he had left it behind. Thankfully I have had the chance to meet my grandfather due to his fortune on this day. I offer my condolences to those who have not been so fortunate." --Emma Cooper

"For futher details about this crash, you may find the study of Karl Weick in Journal of Management Vol 16 n°3 (1990). He highlights some collective responsability in this crash, under cognitive arguments. " --FrenchStudent

"I was 9 years old, living in Switzerland but flying to Spain frequently to see my relatives as my mum's Spanish. I never understood why my mum was so frightened of flying until the day I picked up a magazine at my grandparents in Seville which had a full report on the disaster. It must have been a few days after the accident. The impact it had on me has stayed with me forever. I fly a lot, but every single time I fly I always, always think of the Tenerife collision. One of the most lasting, if not THE most lasting images I have is a full colour, two page spread of one male survivor of the PanAm, standing in front of the burning wreck, clothes in shreds, covered in blood which my grandparents had in their house at the time (it was in Interviu, a Spanish mag). Nearly 27 years on I still think of that man, want to know who he was, where he is. It's incredible how something like this, even though not personally involved, could have such a tremendous impact on me. My heart goes out to everybody who was personally affected by this tragedy by losing someone dear to them." --Erika