Tenerife disaster

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Template:Crash frame Template:Crash title Template:Crash infobox Template:Aircraft title Template:Aircraft infobox Template:Aircraft infobox Template:End frame Image:Tenerife Disaster Collision aftermath 27 March 1977.png The Tenerife disaster took place at 17:06 local time on March 27, 1977, when two Boeing 747 airliners collided at Los Rodeos Airport on the island of Tenerife, Canary Islands, killing 583 people. The accident had the highest fatality number of any accident in aviation history, the terrorist attacks of September 11, 2001 not taken into account.

The aircraft involved were Pan Am Flight 1736, named Clipper Victor, under the command of Captain Victor Grubbs, and KLM Flight 4805, named Rijn (Rhine River), under the command of Captain Jacob Veldhuyzen van Zanten. The accident happened on the ground. The KLM aircraft was just about to take off when it crashed into the Pan Am aircraft which was taxiing on the same runway.

Los Rodeos Airport (then TCI, now TFN) is situated in the northern part of Tenerife, and is used mainly for flights within the Canary Islands and flights from the Spanish mainland.

Contents

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Terrorist bomb threat

Pan Am Flight 1736 had taken off from Los Angeles International Airport with an intermediate stop at New York's JFK International Airport. The aircraft was a Boeing 747-121, registration N736PA. KLM Flight 4805, a charter flight full of vacationers from the Netherlands, had taken off four hours before from Schiphol airport. The destination of both planes was Las Palmas on Gran Canaria.

Upon approaching Gran Canaria International Airport, the Pan Am flight was told that the airport was temporarily closed due to a terrorist bomb attack by Canary Island separatists. A bomb had exploded in the airport concourse, injuring several persons, and a threat of a second had been received. Although the Pan Am crew indicated that they would prefer to circle until landing clearance was given, the plane was ordered to divert to Los Rodeos airport on the neighboring island of Tenerife, together with many other planes. The KLM aircraft was also given instructions to divert to Los Rodeos.

In all, at least five large aircraft were diverted to Los Rodeos, a regional airport that could not easily accommodate them. The airport consisted of one runway and one major taxiway parallel to it, as well as several small taxiways connecting them. The diverted aircraft were parked on the long taxiway, meaning that it could not be used for taxiing. Instead, departing aircraft would have to taxi along the runway to position themselves for takeoff.

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Chain of events leading to disaster

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Refueling

On investigation, the terrorist threat at Las Palmas turned out to be false and the authorities reopened the airport. The Pan Am aircraft, carrying enough fuel to make it to Las Palmas, was waiting to go and ready to taxi and depart. But it was blocked by the KLM plane and a refueling vehicle. Captain van Zanten had decided to refuel at Los Rodeos, instead of Las Palmas, apparently to save time. Once refueling was done, the KLM plane was to depart first, followed by the Pan Am plane.

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Taxiing and weather conditions

Following the tower's instructions, the KLM aircraft taxied to the end of the main runway, and made a 180 degree turn (in aviation terms this is called a 'backtaxi', or 'backtrack', and is difficult with a 747 on the narrow runway) and waited for ATC clearance from air traffic control.

During taxiing, the weather deteriorated. Fog had limited the visual range to 1000 feet (305 meters).

Pan Am was instructed to taxi along the same main runway until it reached exit C3, then to take the exit, get off the main runway, and head to the parallel taxiway. After reaching exit C3, the crew noticed that the aircraft would have to make a 135° turn onto the exit and a 135° turn onto the taxiway.

Since that was an almost impossible task for 747 on an undersized airport, the crew thought that Tenerife ATC must have ordered them to turn at exit C4, which was only 45°. However, the ATC had clearly indicated they had to turn at exit C3 and, in doing so, leave the runway, and not to proceed further along the runway (Source: the CVR transcript).

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Communication problems

Tenerife ATC gave the KLM crew its ATC clearance, which is not a clearance to begin take-off, but a clearance to fly a certain route immediately after take-off. The KLM captain apparently mistook this to be permission for the take-off itself. Captain van Zanten released the brakes and the co-pilot responded with a heavy Dutch accent with words that could either be "We are at take off" or "We are taking off" (see [1]). The control tower was confused by the message and asked for the KLM plane to stand by. However, simultaneous communication from Pan Am caused a heterodyne, making the tower response inaudible to the pilots. Coincidentally, Pan Am was reporting they had not finished taxiing. Either message, if broadcast separately, might have given KLM crew time to abort its takeoff.

Due to the fog, the KLM crew was not able to see the Pan Am 747 taxiing on the runway ahead of them. In addition, neither of the aircraft could be seen from the control tower, and the airport was not equipped with runway radar.

While the KLM crew had started its take-off run, the tower told Pan Am to "report when runway clear". Pan Am radioed back: "OK, we'll report when we're clear". On hearing this, the KLM flight engineer expressed his concern about the Pan Am not being clear of the runway, repeating this concern a few seconds later, but he was overruled by the captain. The flight engineer did not explicitly challenge him on this decision.

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Final radio transmissions

This section of the radio transmission is taken exactly from the original CVR Transcript. 

1706:20.08
TENERIFE TOWER Stand by for take-off, I will call you.
1706:20.3
PanAm Radio(c/p) And we're still taxiing down the runway, the clipper one seven three six.
1706:19.39-  1706:23.19  
RDO and TENERIFE TOWER communications caused a shrill noise in KLM cockpit - 
messages not heard by KLM crew .
1706:25.6
TENERIFE TOWER Roger alpha one seven three six report when runway clear
1706:29.6
PanAm Radio(c/p) OK, we'll report when we're clear.
TENERIFE TOWER Thank you
1706:32.43
KLM FLT ENGR Is hij er niet af dan? {Is he not clear then?}
1706:34.1
KLM CAPTAIN Wat zeg je? {What do you say?}
1706:34.15
KLM-? Yup.
1706:34.7
KLM FLT ENGR Is hij er niet af, die Pan American? {Is he not clear that Pan American?}
1706:35.7
KLM CAPTAIN Jawel. {Oh yes. - emphatic,annoyed}
1706:40.0
PanAm captain sees landing lights of KLM Boeing at approx. 700m
1706:44.0
PH-BUF started rotation
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Collision

Image:Tenerife dis chart1.PNG

Captain Grubbs, Captain of the Pan Am plane, spotted the KLM's landing lights just as the plane approached exit C4, as recorded on the CVR. The Pan Am crew tried to apply full power, and took a sharp left turn onto the exit to avoid a collision. The KLM plane attempted to avoid a collision by climbing away, scraping the tail of the plane along the runway for 20 metres (65 ft). The lower fuselage of the KLM plane hit the upper fuselage of the Pan Am plane, ripping apart the center of the Pan Am jet nearly directly above the wing. The KLM plane slammed into the ground belly-up 150 m past the point of collision and slid down the runway.

All 234 passengers and 14 crew members in the KLM plane were killed, and 335 of the 396 aboard the Pan Am flight (326 passengers and 9 crew members) perished, primarily due to the fire and explosions resulting from the fuel spilled in the impact. The Pan Am Captain, First Officer, and Flight Engineer were among the survivors (56 passengers and 5 crew members). Image:Tenerife collision.jpg

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Investigation

About 70 crash investigators from Spain, the Netherlands, the United States, and the two airline companies were involved in the investigation. Facts showed that there had been misinterpretations and false assumptions. Analysis of the cockpit voice recorder (CVR) transcript showed that the KLM pilot was convinced that he had been cleared for take-off, while the Tenerife control tower was certain that the KLM 747 was stationary at the end of the runway and awaiting takeoff clearance.

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Probable cause

While there is debate about their relative importance, the general conclusion is that the disaster was caused partly by:

  • the fact that the KLM Captain did not interrupt take-off when Pan Am reported that they were still on the runway.
  • In reply to the flight engineer's query as to whether the Pan Am airplane had already left the runway, replied emphatically in the affirmative.
  • squelched radio messages (calls from both planes to the tower and vice versa canceled each other because they happened to be at precisely the same instant)
  • the use of non-standard phrases used by the KLM co-pilot ("We're at take off") and the Tenerife control tower ("O.K."),
  • the fact that the Pan Am crew continued along the runway instead of turning at exit C3, as directed.
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Speculations

There has been speculation of other, albeit unverifiable, possible contributing factors.

  • Van Zanten was known as a first-class pilot, and even was the preferred pilot for publicity, such as KLM magazine ads. The flight was one of the few after spending six months training new pilots on a flight simulator. Some experts claim in time he might have developed some kind of governance attitude as a consequence of having been in charge of everything at the simulator (including simulated ATC), which is another reason suggested for van Zanten not confirming the instructions from the tower.
  • The flight engineer apparently hesitated to further challenge van Zanten, possibly because van Zanten was not only senior in rank, but also one of the most able and experienced pilots working for the airline.
  • The possibility that Captain van Zanten was in a hurry to commence the delayed flight due to Dutch regulations on exceeding crew duty hours.
  • The deteriorating weather conditions could prevent the flight from taking off at all, and the airliner would be forced to stay on Los Rodeos, with financial consequences for KLM.
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Safety response

As a consequence of the accident, there were sweeping changes made to international airline regulations and to airplanes. Aviation authorities around the world introduced requirements for standard phrases and a greater emphasis on English as a common working language. For example, ICAO calls for the phrase "line up and wait" as an instruction to an aircraft moving into position but not cleared for take-off. The FAA equivalent is "taxi into position and hold". Air traffic instruction should not be acknowledged solely with a colloquial phrase such as "OK" or even "Roger", but with a read back of the key parts of the instruction, to show mutual understanding.

Cockpit procedures were also changed. Hierarchical relations among crewmembers were played down. More emphasis was placed on decision-making by mutual agreement. This is known in the industry as crew resource management, and is now standard training in all major airlines.

Due to the frequent and dangerous fogs that cover the area around Los Rodeos airport in the North of the island, a second airport was built in the South of the Island: the new Reina Sofía Airport. This airport serves the majority of Tenerife's domestic and international commercial flights.

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Trivia

  • The Pan Am plane happened to have been the first 747 to carry fare-paying passengers, on a flight from New York to London on 21 January 1970.

Well-known people who were killed in the disaster were:

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See also

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Sources

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External links

es:Colisión de 1977 en Los Rodeos fr:Catastrophe de Ténérife he:אסון המטוסים בטנריף nl:Vliegtuigramp Tenerife ja:テネリフェの悲劇 no:Tenerife-ulykken pl:Katastrofa lotnicza na Teneryfie fi:Teneriffan lento-onnettomuus sv:Flygolyckan på Teneriffa zh:加纳利空难

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