Tenerife disaster
Encyclopedia
The Tenerife airport disaster occurred on March 27, 1977, when two Boeing 747
passenger aircraft collided on the runway of Los Rodeos Airport (now known as Tenerife North Airport) on the Spanish island of Tenerife
, one of the Canary Islands
. With a total of 583 fatalities, the crash is the deadliest accident in aviation history.
The aircraft involved, KLM Flight 4805 and Pan Am
Flight 1736, were, along with many other aircraft, diverted to Tenerife from Gran Canaria Airport after a bomb exploded there. The threat of a second bomb forced the authorities to close the airport while a search was conducted. So many airplanes were diverted to the smaller Tenerife airport that controllers were forced to park many of them on the taxiway, thereby blocking it. Further complicating the situation, while waiting for authorities to reopen Gran Canaria, a dense fog developed at Tenerife, greatly reducing visibility. When Gran Canaria reopened, the parked aircraft blocking the taxiway at Tenerife required both 747s to taxi on the only runway in order to get in position for takeoff. Due to the fog, neither aircraft could see the other, nor could the controller in the tower see the runway or the two 747s on it. As the airport did not have ground radar, the only means for the controller to identify the location of each airplane was via voice reports over the radio. As a result of several misunderstandings in the ensuing communication, the KLM flight attempted to take off while the Pan Am flight was still on the runway. The resulting collision destroyed both aircraft, killing all 248 aboard the KLM flight and 335 out of 396 aboard the Pan Am flight. 61 people aboard the Pan Am flight, including the pilots and flight engineer, survived the disaster.
As the accident occurred on Spanish territory, that nation was responsible for investigating the accident. Investigators from the Netherlands and the United States also participated. The investigation would reveal the primary cause of the accident was the captain of the KLM flight took off without clearance from Air Traffic Control
. The investigation would however specify that the captain did not intentionally take off without clearance, rather he fully believed he had clearance to take off due to misunderstandings between his flight crew and ATC. Dutch investigators would place a greater emphasis on this than their American and Spanish counterparts, but ultimately KLM would admit their crew was responsible for the accident, and the airline financially compensated the victims.
The accident had a large influence on the industry, particularly in the area of communication. An increased emphasis was placed on using standardized phraseology in ATC communication by both controllers and pilots alike, thereby reducing the chance for misunderstandings. As part of these changes, the word "takeoff" was removed from general usage, and is only spoken by ATC when actually clearing an aircraft to take off. Less experienced flight crew members were encouraged to challenge their captains when they believed something was not correct, and captains were instructed to listen to their crew and evaluate all decisions in light of crew concerns. This concept would later be expanded into what is known today as Crew Resource Management
. CRM training is now mandatory for all airline pilots.
on the nearby island of Gran Canaria
. Both are in the Canary Islands, an autonomous community of Spain located in the Atlantic Ocean off the west coast of Morocco
.
Pan Am Flight 1736 had taken off from Los Angeles International Airport
with an intermediate stop at New York's John F. Kennedy International Airport
. The aircraft was a Boeing 747–121, registration N736PA. Of the 380 passengers, 14 had boarded in New York, where the crew was also changed. The new crew consisted of captain Victor Grubbs, First Officer Robert Bragg, and Flight Engineer George Warns; there were 13 other crew members. The same aircraft had operated the inaugural 747 commercial flight on January 22, 1970.
KLM Flight 4805, a charter flight for Holland International Travel Group from the Netherlands, had taken off four hours before from Amsterdam Airport Schiphol. Its captain was Jacob Veldhuyzen van Zanten
and the first officer was Klaas Meurs. The aircraft was a Boeing 747-206B, registration PH-BUF. The KLM jet had 14 crew members and 235 passengers, including 48 children and three infants. Most of the KLM passengers were Dutch; four Germans, two Austrians, and two Americans were also on the plane. After the aircraft landed at Tenerife, a Dutch tour guide named Robina van Lanschot, who lived on the island in the town of Puerto de la Cruz
and wanted to see her boyfriend there that night, chose not to re-board the 747, leaving 234 passengers on board.
) exploded in the terminal of Gran Canaria International Airport. It had been preceded by a phone call warning of the bomb, and soon after another call came in claiming a second bomb was at the airport. The civil aviation authorities closed that airport after the bomb detonated and diverted all of its incoming flights to Los Rodeos, including the two Boeing 747 aircraft involved in the disaster.
Upon contacting Gran Canaria airport, the Pan Am flight was informed of the temporary closure. Although the Pan Am crew indicated that they would prefer to circle in a holding pattern until landing clearance was given, the plane was ordered to divert to Los Rodeos, along with the KLM flight. This led to the critical cramped aircraft conditions within the smaller airport.
and one major taxiway
parallel to it, as well as several small taxiways connecting the main taxiway and the runway. While waiting for Gran Canaria airport to reopen, the diverted aircraft took up so much space that they 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, a procedure known as a runway backtaxi
.
. Because the flight crew was performing the checklist, copying this clearance was postponed until the aircraft was in takeoff position on Runway 30. During taxiing, the weather deteriorated and low-lying clouds now limited the visual range to about 300 m (984.3 ft). Legal or stipulated threshold for takeoff was 700 m (2,296.6 ft) visibility, as noted in the NOVA documentary and relayed by surviving Pan Am co-pilot Robert Bragg.
Shortly afterward, Pan Am 1736 was instructed to also backtaxi, to follow the KLM aircraft down the same runway, to exit the runway by taking the "third exit" on their left and then use the parallel taxiway. Initially the crew was unclear as to whether the controller had told them to take the first or third exit. The crew asked for clarification and the controller responded emphatically by replying: "The third one, sir; one, two, three; third, third one". The crew began the taxi and proceeded to identify the unmarked taxiways using an airport diagram as they reached them.
Based on the chronology of the cockpit voice recorder (CVR)
and the distances between the taxiways (and the location of the aircraft at the time of the collision), the crew successfully identified the first two taxiways (C-1 and C-2), but their discussion in the cockpit never indicated that they had sighted the third taxiway (C-3), which they had been instructed to use. There were no markings or signs to identify the runway exits. The Pan Am crew appeared to remain unsure of their position on the runway until the collision, which occurred near the intersection with the fourth taxiway (C-4). Pan Am's lack of visibility and runway exiting confusion probably contributed to a slow taxi speed, thereby causing the aircraft to remain on the runway longer than anticipated.
The angle of the third taxiway would have required the plane to perform a turn of approximately 148°, which would lead counter-productively back toward the still-crowded main apron. At the end of C-3 another 148° turn would have to be made to continue taxiing towards the start of the runway. Taxiway C-4 would have required two turns of just 35°. A study carried out by the Air Line Pilots Association after the accident concluded that making the second 148° turn at the end of taxiway C-3 would have been "a practical impossibility", although the Dutch report stated that such a maneuver "could reasonably be performed". The official report from the Spanish authorities did not explain why the controller had instructed the Pan Am aircraft to use the third taxiway, rather than the sensible and easier fourth taxiway.
Immediately after lining up, the KLM captain advanced the throttles (a standard procedure known as "spool-up", to verify that the engines are operating properly for takeoff) and the co-pilot, surprised by the maneuver, quickly advised the captain that ATC clearance had not yet been given. Captain Van Zanten responded, "I know that. Go ahead, ask." Meurs then radioed the tower that they were "ready for takeoff" and "waiting for our ATC clearance". The KLM crew then received instructions which specified the route that the aircraft was to follow after takeoff. The instructions used the word "takeoff," but did not include an explicit statement that they were cleared for takeoff.
Meurs read the flight clearance back to the controller, completing the readback with the statement: "We are now at takeoff." Captain Van Zanten interrupted the co-pilot's read-back with the comment, "We're going." As noted in the NOVA documentary of the incident, the co-pilot chose not to embarrass his superior a second time by stating that they still did not have the proper clearance to take off.
The controller, who could not see the runway due to the fog, initially responded with "OK" (terminology which is nonstandard), which reinforced the KLM captain's misinterpretation that they had takeoff clearance. The controller's response of "OK" to the co-pilot's nonstandard statement that they were "now at takeoff" was likely due to his misinterpretation that they were in takeoff position and ready to begin the roll when takeoff clearance was received, but not actually in the process of taking off. The controller then immediately added "stand by for takeoff, I will call you," indicating that he had not intended the clearance to be interpreted as a takeoff clearance. He probably had not heard the captain's announcement that they were "going," since Van Zanten had said this to his fellow crew members and not transmitted it on the radio himself.
A simultaneous radio call from the Pan Am crew caused mutual interference
on the radio frequency, which was audible in the KLM cockpit as a three second long whistling sound (or heterodyne
). This made the crucial latter portion of the tower's response audible only with difficulty by the KLM crew. The Pan Am crew's transmission, which was also critical, was reporting, "We're still taxiing down the runway, the Clipper 1736!" This message was also blocked by the heterodyne and inaudible to the KLM crew. Either message, if heard in the KLM cockpit, would have given the KLM crew time to abort its second takeoff attempt.
Due to the fog, neither crew was able to see the other plane 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 ground radar
.
After the KLM plane had started its takeoff roll, the tower instructed the Pan Am crew to "report when runway clear." The Pan Am crew replied: "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 by asking the pilots in his own cockpit, "Is he not clear, that Pan American?" Van Zanten emphatically replied "Oh, yes" and continued with the takeoff.
According to the CVR, Captain Grubbs, captain of the Pan Am plane, spotted the KLM's landing lights just as the plane approached exit C-4, exclaiming, "Goddamn, that son-of-a-bitch is coming straight at us!" while the co-pilot Robert Bragg yelled, "Get off! Get off! Get off!". The Pan Am crew applied full power and took a sharp left turn towards the grass to avoid a collision. KLM Captain Van Zanten, already traveling too fast to stop, also attempted to avoid a collision by prematurely rotating his aircraft and attempting to climb away, scraping the tail of the plane along the runway for 20 m (65.6 ft). As the KLM left the ground its steep angle of attack
allowed the nose gear to clear the Pan Am but the engines, lower fuselage
and aft landing gears struck the upper right side of the Pan Am's fuselage at approximately 140 kn (274.4 km/h; 170.5 mph), ripping apart the center of the Pan Am jet almost directly above the wing. The right side engines crashed through the Pan Am's upper deck immediately behind the cockpit.
The KLM plane was briefly airborne, but the impact with the Pan Am had sheared off the #1 (outer left) engine, and the #2 (inner left) engine had ingested significant amounts of shredded materials from the Pan Am. The KLM pilot quickly lost control, and the 747 went into a stall, rolled sharply, and hit the ground at a point 150 m (492.1 ft) past the collision, sliding a further 300 m down the runway. The full load of fuel which had caused the earlier delay ignited immediately.
A survivor of the Pan Am flight, John Coombs of Haleiwa, Hawaii, said that sitting in the nose of the plane probably saved his life: "We all settled back, and the next thing an explosion took place and the whole port side, left side of the plane, was just torn wide open."
Both airplanes were destroyed. All 234 passengers and 14 crew members in the KLM plane died, while 326 passengers and 9 crew members aboard the Pan Am flight were killed, primarily due to the fire and explosions resulting from the fuel spilled and ignited in the impact. The other 56 passengers and 5 crew members aboard the Pan Am aircraft survived, including the pilots and flight engineer. Most of the survivors on the Pan Am aircraft walked out onto the left wing, the side away from the collision, through holes in the fuselage structure. The Pan Am's engines were still running at takeoff power for a few minutes after the accident despite First Officer Bragg's intention to turn them off. The top part of the cockpit, where the engine switches were located, had been destroyed in the collision, and all control lines were severed, leaving no method for the flight crew to control the aircraft's systems. After a short time running at full power the Pan-Am's engines began to disintegrate, throwing engine parts at high speed that killed a flight attendant who had escaped the burning plane. Survivors waited for rescue, but it did not come promptly as the firefighters were initially unaware that there were two aircraft involved and were concentrating on the KLM wreck some distance away in the thick fog. Eventually, most of the survivors on the wings dropped to the ground below.
Captain Veldhuyzen van Zanten was KLM's chief of flight training and the airline's preferred pilot for publicity such as magazine advertisements. As such, KLM attempted to contact him to give public statements regarding the disaster, before learning that he was the captain involved. He had in fact given the co-pilot on the ill-fated flight his Boeing 747 qualification check about two months before the accident.
Subsequent to the crash, first officer Robert Bragg, who was responsible for handling the Pan Am's radio communications, made public statements which conflict with statements made by the Pan Am crew in the official transcript of the CVR. In the documentary Crash of the Century (produced by the makers of Mayday
), he stated he was convinced the tower controller had intended they take the fourth exit C-4 because the controller delivered the message to take "the third one, sir; one, two, three; third, third one" after the Pan Am had already passed C-1 (making C-4 the third exit counting from there). The CVR shows unequivocally that they received this message before they identified C-1, with the position of the aircraft somewhere between the entrance and C-1. Also, in a Time
article, Bragg stated that he made the statement "What's he doing? He'll kill us all!" which does not appear in the CVR transcript.
Other major factors contributing to the accident were:
The following factors were considered contributing but not critical:
In particular, the Dutch response pointed out that
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 takeoff. Also several national air safety boards began penalizing pilots for disobeying air traffic controllers' orders. Air traffic instruction should not be acknowledged solely with a colloquial phrase such as "OK" or even "Roger
", but with a readback of the key parts of the instruction, to show mutual understanding. Additionally, the phrase "takeoff" is only spoken when the actual takeoff clearance is given. Up until that point, both aircrew and controllers should use the phrase "departure" in its place (e.g. "ready for departure"). Cockpit procedures were also changed. Hierarchical relations among crew members were played down. More emphasis was placed on team decision-making by mutual agreement. This is known in the industry as Crew Resource Management
.
In 1978 a second airport was inaugurated on the island: the new Tenerife South Airport
(TFS). This airport now serves the majority of international tourist flights. Los Rodeos, renamed to Tenerife North Airport (TFN), was then used only for domestic and inter-island flights, but in 2002 a new terminal was opened and it carries international traffic once again, including budget airlines. The Spanish authorities installed a ground radar at Tenerife North following the accident.
A Dutch national memorial and final resting place for the victims of the KLM plane is located in Amsterdam
, at Westgaarde cemetery. There is also a memorial at the Westminster Memorial Park and Mortuary in Westminster, California
.
The 30th anniversary marked the first time that Dutch and American next of kin, and aid helpers from Tenerife, joined in international commemoration service held at the Auditorio de Tenerife in Santa Cruz; the International Tenerife Memorial March 27, 1977
was inaugurated at the Mesa Mota March 27, 2007. The monument was designed by Dutch sculptor Rudi van de Wint. A special 50-page commemorative booklet including a DVD in English, Dutch, and Spanish was published a year later, on March 27, 2008.
episode Blaming the Pilot, the Seconds From Disaster
episode Collision on the Runway, PBS's NOVA
episode "The Deadliest Plane Crash" in 2006, and the Discovery Channel
TV series Most Deadly and Destroyed In Seconds
.
Boeing 747
The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...
passenger aircraft collided on the runway of Los Rodeos Airport (now known as Tenerife North Airport) on the Spanish island of Tenerife
Tenerife
Tenerife is the largest and most populous island of the seven Canary Islands, it is also the most populated island of Spain, with a land area of 2,034.38 km² and 906,854 inhabitants, 43% of the total population of the Canary Islands. About five million tourists visit Tenerife each year, the...
, one of the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
. With a total of 583 fatalities, the crash is the deadliest accident in aviation history.
The aircraft involved, KLM Flight 4805 and Pan Am
Pan American World Airways
Pan American World Airways, commonly known as Pan Am, was the principal and largest international air carrier in the United States from 1927 until its collapse on December 4, 1991...
Flight 1736, were, along with many other aircraft, diverted to Tenerife from Gran Canaria Airport after a bomb exploded there. The threat of a second bomb forced the authorities to close the airport while a search was conducted. So many airplanes were diverted to the smaller Tenerife airport that controllers were forced to park many of them on the taxiway, thereby blocking it. Further complicating the situation, while waiting for authorities to reopen Gran Canaria, a dense fog developed at Tenerife, greatly reducing visibility. When Gran Canaria reopened, the parked aircraft blocking the taxiway at Tenerife required both 747s to taxi on the only runway in order to get in position for takeoff. Due to the fog, neither aircraft could see the other, nor could the controller in the tower see the runway or the two 747s on it. As the airport did not have ground radar, the only means for the controller to identify the location of each airplane was via voice reports over the radio. As a result of several misunderstandings in the ensuing communication, the KLM flight attempted to take off while the Pan Am flight was still on the runway. The resulting collision destroyed both aircraft, killing all 248 aboard the KLM flight and 335 out of 396 aboard the Pan Am flight. 61 people aboard the Pan Am flight, including the pilots and flight engineer, survived the disaster.
As the accident occurred on Spanish territory, that nation was responsible for investigating the accident. Investigators from the Netherlands and the United States also participated. The investigation would reveal the primary cause of the accident was the captain of the KLM flight took off without clearance from Air Traffic Control
Air traffic control
Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...
. The investigation would however specify that the captain did not intentionally take off without clearance, rather he fully believed he had clearance to take off due to misunderstandings between his flight crew and ATC. Dutch investigators would place a greater emphasis on this than their American and Spanish counterparts, but ultimately KLM would admit their crew was responsible for the accident, and the airline financially compensated the victims.
The accident had a large influence on the industry, particularly in the area of communication. An increased emphasis was placed on using standardized phraseology in ATC communication by both controllers and pilots alike, thereby reducing the chance for misunderstandings. As part of these changes, the word "takeoff" was removed from general usage, and is only spoken by ATC when actually clearing an aircraft to take off. Less experienced flight crew members were encouraged to challenge their captains when they believed something was not correct, and captains were instructed to listen to their crew and evaluate all decisions in light of crew concerns. This concept would later be expanded into what is known today as Crew Resource Management
Crew Resource Management
Crew resource management or Cockpit resource management is a procedure and training system in systems where human error can have devastating effects. Used primarily for improving air safety, CRM focuses on interpersonal communication, leadership, and decision making in the cockpit...
. CRM training is now mandatory for all airline pilots.
Flight history
For both planes, Tenerife was an unscheduled stop. Their destination was Gran Canaria International Airport (also known as Las Palmas Airport), serving Las PalmasLas Palmas de Gran Canaria
Las Palmas de Gran Canaria commonly known as Las Palmas is the political capital, jointly with Santa Cruz, the most populous city in the Autonomous Community of the Canary Islands and the ninth largest city in Spain, with a population of 383,308 in 2010. Nearly half of the people of the island...
on the nearby island of Gran Canaria
Gran Canaria
Gran Canaria is the second most populous island of the Canary Islands, with a population of 838,397 which constitutes approximately 40% of the population of the archipelago...
. Both are in the Canary Islands, an autonomous community of Spain located in the Atlantic Ocean off the west coast of Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
.
Pan Am Flight 1736 had taken off from Los Angeles International Airport
Los Angeles International Airport
Los Angeles International Airport is the primary airport serving the Greater Los Angeles Area, the second-most populated metropolitan area in the United States. It is most often referred to by its IATA airport code LAX, with the letters pronounced individually...
with an intermediate stop at New York's John F. Kennedy International Airport
John F. Kennedy International Airport
John F. Kennedy International Airport is an international airport located in the borough of Queens in New York City, about southeast of Lower Manhattan. It is the busiest international air passenger gateway to the United States, handling more international traffic than any other airport in North...
. The aircraft was a Boeing 747–121, registration N736PA. Of the 380 passengers, 14 had boarded in New York, where the crew was also changed. The new crew consisted of captain Victor Grubbs, First Officer Robert Bragg, and Flight Engineer George Warns; there were 13 other crew members. The same aircraft had operated the inaugural 747 commercial flight on January 22, 1970.
KLM Flight 4805, a charter flight for Holland International Travel Group from the Netherlands, had taken off four hours before from Amsterdam Airport Schiphol. Its captain was Jacob Veldhuyzen van Zanten
Jacob Veldhuyzen van Zanten
Jacob Louis Veldhuyzen van Zanten was a Dutch aircraft captain and flight instructor. He was the captain of the ill-fated KLM Royal Dutch Airlines Boeing 747 which was involved in the Tenerife airport disaster.-Biography:...
and the first officer was Klaas Meurs. The aircraft was a Boeing 747-206B, registration PH-BUF. The KLM jet had 14 crew members and 235 passengers, including 48 children and three infants. Most of the KLM passengers were Dutch; four Germans, two Austrians, and two Americans were also on the plane. After the aircraft landed at Tenerife, a Dutch tour guide named Robina van Lanschot, who lived on the island in the town of Puerto de la Cruz
Puerto de la Cruz
Puerto de la Cruz is a city and municipality located in Spain, on the north coast of Tenerife island, in the Orotava Valley...
and wanted to see her boyfriend there that night, chose not to re-board the 747, leaving 234 passengers on board.
Bombing at Las Palmas
Events on both planes had been routine until they approached the islands. Then, at 1:15 pm, a bomb (planted by the separatist Fuerzas Armadas GuanchesFuerzas Armadas Guanches
The Fuerzas Armadas Guanches was the armed wing of the Movimiento por la Autodeterminación e Independencia del Archipiélago Canario...
) exploded in the terminal of Gran Canaria International Airport. It had been preceded by a phone call warning of the bomb, and soon after another call came in claiming a second bomb was at the airport. The civil aviation authorities closed that airport after the bomb detonated and diverted all of its incoming flights to Los Rodeos, including the two Boeing 747 aircraft involved in the disaster.
Upon contacting Gran Canaria airport, the Pan Am flight was informed of the temporary closure. Although the Pan Am crew indicated that they would prefer to circle in a holding pattern until landing clearance was given, the plane was ordered to divert to Los Rodeos, along with the KLM flight. This led to the critical cramped aircraft conditions within the smaller airport.
Congestion at 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 had only one runwayRunway
According to ICAO a runway is a "defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft." Runways may be a man-made surface or a natural surface .- Orientation and dimensions :Runways are named by a number between 01 and 36, which is generally one tenth...
and one major taxiway
Taxiway
A taxiway is a path on an airport connecting runways with ramps, hangars, terminals and other facilities. They mostly have hard surface such as asphalt or concrete, although smaller airports sometimes use gravel or grass....
parallel to it, as well as several small taxiways connecting the main taxiway and the runway. While waiting for Gran Canaria airport to reopen, the diverted aircraft took up so much space that they were parked on the long taxiway, meaning that it could not be used for taxiing
Taxiing
Taxiing refers to the movement of an aircraft on the ground, under its own power, in contrast to towing or push-back where the aircraft is moved by a tug...
. Instead, departing aircraft would have to taxi along the runway to position themselves for takeoff, a procedure known as a runway backtaxi
Backtaxi
Backtaxi is an airport ground procedure which involves the use of any portion of a runway as a taxiway for an aircraft to taxi in the opposite direction from which it will take off or has landed...
.
Refuelling
After the threat at Gran Canaria International Airport had been contained, authorities reopened the airport. The Pan Am aircraft was ready to depart, but the KLM plane and a refuelling vehicle obstructed the way to the active runway. The Pan Am aircraft was unable to maneuver around the fueling KLM, reach the runway and depart due to a lack of just 12 ft (3.7 m) of clearance. Captain Van Zanten had decided to fully refuel at Los Rodeos instead of Las Palmas, apparently to save time. The refuelling took about 35 minutes.Taxiing and weather conditions
Following the tower's instructions, the KLM aircraft was cleared to backtaxi the full length of runway 30 and make a 180° turn to put the aircraft in takeoff position. While KLM 4805 was backtaxiing on runway 30, the controller asked the flight crew to report when it was ready to copy the ATC clearanceInstrument flight rules
Instrument flight rules are one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other are visual flight rules ....
. Because the flight crew was performing the checklist, copying this clearance was postponed until the aircraft was in takeoff position on Runway 30. During taxiing, the weather deteriorated and low-lying clouds now limited the visual range to about 300 m (984.3 ft). Legal or stipulated threshold for takeoff was 700 m (2,296.6 ft) visibility, as noted in the NOVA documentary and relayed by surviving Pan Am co-pilot Robert Bragg.
Shortly afterward, Pan Am 1736 was instructed to also backtaxi, to follow the KLM aircraft down the same runway, to exit the runway by taking the "third exit" on their left and then use the parallel taxiway. Initially the crew was unclear as to whether the controller had told them to take the first or third exit. The crew asked for clarification and the controller responded emphatically by replying: "The third one, sir; one, two, three; third, third one". The crew began the taxi and proceeded to identify the unmarked taxiways using an airport diagram as they reached them.
Based on the chronology of the cockpit voice recorder (CVR)
Cockpit voice recorder
A cockpit voice recorder , often referred to as a "black box", is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents...
and the distances between the taxiways (and the location of the aircraft at the time of the collision), the crew successfully identified the first two taxiways (C-1 and C-2), but their discussion in the cockpit never indicated that they had sighted the third taxiway (C-3), which they had been instructed to use. There were no markings or signs to identify the runway exits. The Pan Am crew appeared to remain unsure of their position on the runway until the collision, which occurred near the intersection with the fourth taxiway (C-4). Pan Am's lack of visibility and runway exiting confusion probably contributed to a slow taxi speed, thereby causing the aircraft to remain on the runway longer than anticipated.
The angle of the third taxiway would have required the plane to perform a turn of approximately 148°, which would lead counter-productively back toward the still-crowded main apron. At the end of C-3 another 148° turn would have to be made to continue taxiing towards the start of the runway. Taxiway C-4 would have required two turns of just 35°. A study carried out by the Air Line Pilots Association after the accident concluded that making the second 148° turn at the end of taxiway C-3 would have been "a practical impossibility", although the Dutch report stated that such a maneuver "could reasonably be performed". The official report from the Spanish authorities did not explain why the controller had instructed the Pan Am aircraft to use the third taxiway, rather than the sensible and easier fourth taxiway.
Communication misunderstandings
| Cockpit and ATC tower communications | |
|---|---|
These communications are taken from the cockpit voice recorders of both aircraft, as well as from the Tenerife control tower's tapes.
|
|
Immediately after lining up, the KLM captain advanced the throttles (a standard procedure known as "spool-up", to verify that the engines are operating properly for takeoff) and the co-pilot, surprised by the maneuver, quickly advised the captain that ATC clearance had not yet been given. Captain Van Zanten responded, "I know that. Go ahead, ask." Meurs then radioed the tower that they were "ready for takeoff" and "waiting for our ATC clearance". The KLM crew then received instructions which specified the route that the aircraft was to follow after takeoff. The instructions used the word "takeoff," but did not include an explicit statement that they were cleared for takeoff.
Meurs read the flight clearance back to the controller, completing the readback with the statement: "We are now at takeoff." Captain Van Zanten interrupted the co-pilot's read-back with the comment, "We're going." As noted in the NOVA documentary of the incident, the co-pilot chose not to embarrass his superior a second time by stating that they still did not have the proper clearance to take off.
The controller, who could not see the runway due to the fog, initially responded with "OK" (terminology which is nonstandard), which reinforced the KLM captain's misinterpretation that they had takeoff clearance. The controller's response of "OK" to the co-pilot's nonstandard statement that they were "now at takeoff" was likely due to his misinterpretation that they were in takeoff position and ready to begin the roll when takeoff clearance was received, but not actually in the process of taking off. The controller then immediately added "stand by for takeoff, I will call you," indicating that he had not intended the clearance to be interpreted as a takeoff clearance. He probably had not heard the captain's announcement that they were "going," since Van Zanten had said this to his fellow crew members and not transmitted it on the radio himself.
A simultaneous radio call from the Pan Am crew caused mutual interference
Interference (communication)
In communications and electronics, especially in telecommunications, interference is anything which alters, modifies, or disrupts a signal as it travels along a channel between a source and a receiver. The term typically refers to the addition of unwanted signals to a useful signal...
on the radio frequency, which was audible in the KLM cockpit as a three second long whistling sound (or heterodyne
Heterodyne
Heterodyning is a radio signal processing technique invented in 1901 by Canadian inventor-engineer Reginald Fessenden where high frequency signals are converted to lower frequencies by combining two frequencies. Heterodyning is useful for frequency shifting information of interest into a useful...
). This made the crucial latter portion of the tower's response audible only with difficulty by the KLM crew. The Pan Am crew's transmission, which was also critical, was reporting, "We're still taxiing down the runway, the Clipper 1736!" This message was also blocked by the heterodyne and inaudible to the KLM crew. Either message, if heard in the KLM cockpit, would have given the KLM crew time to abort its second takeoff attempt.
Due to the fog, neither crew was able to see the other plane 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 ground radar
Surface movement radar
Surface Movement Radar is used to detect aircraft and vehicles on the surface of an airport. It is used by air traffic controllers to supplement visual observations. It may also be used at night time and during low visibility to monitor the movement of aircraft and vehicles...
.
After the KLM plane had started its takeoff roll, the tower instructed the Pan Am crew to "report when runway clear." The Pan Am crew replied: "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 by asking the pilots in his own cockpit, "Is he not clear, that Pan American?" Van Zanten emphatically replied "Oh, yes" and continued with the takeoff.
Collision
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...
allowed the nose gear to clear the Pan Am but the engines, lower fuselage
Fuselage
The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...
and aft landing gears struck the upper right side of the Pan Am's fuselage at approximately 140 kn (274.4 km/h; 170.5 mph), ripping apart the center of the Pan Am jet almost directly above the wing. The right side engines crashed through the Pan Am's upper deck immediately behind the cockpit.
The KLM plane was briefly airborne, but the impact with the Pan Am had sheared off the #1 (outer left) engine, and the #2 (inner left) engine had ingested significant amounts of shredded materials from the Pan Am. The KLM pilot quickly lost control, and the 747 went into a stall, rolled sharply, and hit the ground at a point 150 m (492.1 ft) past the collision, sliding a further 300 m down the runway. The full load of fuel which had caused the earlier delay ignited immediately.
A survivor of the Pan Am flight, John Coombs of Haleiwa, Hawaii, said that sitting in the nose of the plane probably saved his life: "We all settled back, and the next thing an explosion took place and the whole port side, left side of the plane, was just torn wide open."
Both airplanes were destroyed. All 234 passengers and 14 crew members in the KLM plane died, while 326 passengers and 9 crew members aboard the Pan Am flight were killed, primarily due to the fire and explosions resulting from the fuel spilled and ignited in the impact. The other 56 passengers and 5 crew members aboard the Pan Am aircraft survived, including the pilots and flight engineer. Most of the survivors on the Pan Am aircraft walked out onto the left wing, the side away from the collision, through holes in the fuselage structure. The Pan Am's engines were still running at takeoff power for a few minutes after the accident despite First Officer Bragg's intention to turn them off. The top part of the cockpit, where the engine switches were located, had been destroyed in the collision, and all control lines were severed, leaving no method for the flight crew to control the aircraft's systems. After a short time running at full power the Pan-Am's engines began to disintegrate, throwing engine parts at high speed that killed a flight attendant who had escaped the burning plane. Survivors waited for rescue, but it did not come promptly as the firefighters were initially unaware that there were two aircraft involved and were concentrating on the KLM wreck some distance away in the thick fog. Eventually, most of the survivors on the wings dropped to the ground below.
Captain Veldhuyzen van Zanten was KLM's chief of flight training and the airline's preferred pilot for publicity such as magazine advertisements. As such, KLM attempted to contact him to give public statements regarding the disaster, before learning that he was the captain involved. He had in fact given the co-pilot on the ill-fated flight his Boeing 747 qualification check about two months before the accident.
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 CVR transcript showed that the KLM pilot was convinced that he had been cleared for takeoff, while the Tenerife control tower was certain that the KLM 747 was stationary at the end of the runway and awaiting takeoff clearance. It appears KLM's co-pilot was not as certain about take-off clearance as the captain.Subsequent to the crash, first officer Robert Bragg, who was responsible for handling the Pan Am's radio communications, made public statements which conflict with statements made by the Pan Am crew in the official transcript of the CVR. In the documentary Crash of the Century (produced by the makers of Mayday
Mayday (TV series)
Mayday, also known as Air Crash Investigation in the United Kingdom, Australia and Asia and Air Emergency and Air Disasters in the United States, is a Canadian documentary television programme produced by Cineflix investigating air crashes, near-crashes and other disasters...
), he stated he was convinced the tower controller had intended they take the fourth exit C-4 because the controller delivered the message to take "the third one, sir; one, two, three; third, third one" after the Pan Am had already passed C-1 (making C-4 the third exit counting from there). The CVR shows unequivocally that they received this message before they identified C-1, with the position of the aircraft somewhere between the entrance and C-1. Also, in a Time
Time (magazine)
Time is an American news magazine. A European edition is published from London. Time Europe covers the Middle East, Africa and, since 2003, Latin America. An Asian edition is based in Hong Kong...
article, Bragg stated that he made the statement "What's he doing? He'll kill us all!" which does not appear in the CVR transcript.
Probable cause
The investigation concluded that the fundamental cause of the accident was that Captain Van Zanten took off without takeoff clearance. The investigators suggested the reason for his mistake might have been a desire to leave as soon as possible in order to comply with KLM's duty-time regulations, and before the weather deteriorated further.Other major factors contributing to the accident were:
- The sudden fog greatly limited visibility. The control tower and the crews of both planes were unable to see one another.
- Simultaneous radio transmissions, with the result that neither message could be heard.
The following factors were considered contributing but not critical:
- Use of ambiguous non-standard phrases by the KLM co-pilot ("We're at take off") and the Tenerife control tower ("OK").
- The Pan Am aircraft had not exited the runway at C-3.
- The airport was (due to rerouting from the bomb threat) forced to accommodate a great number of large aircraft, resulting in disruption of the normal use of taxiways.
Dutch response
The Dutch authorities were reluctant to accept the Spanish report blaming the KLM captain for the accident. The Netherlands Department of Civil Aviation published a response that, whilst accepting that the KLM aircraft had taken off "prematurely", argued that he alone should not be blamed for the "mutual misunderstanding" that occurred between the controller and the KLM crew, and that limitations of using radio as a means of communication should have been given greater consideration.In particular, the Dutch response pointed out that
- the crowded airport had placed additional pressure on all parties, KLM, Pan Am, and the controller;
- sounds on the CVR suggested that during the incident the Spanish control tower crew had been listening to a football match on the radio and may have been distracted.
- the transmission from the tower in which the controller passed KLM their ATC clearance was ambiguous and could have been interpreted as also giving take-off clearance. In support of this part of their response, the Dutch investigators pointed out that Pan Am's messages "No! Eh?" and "We are still taxiing down the runway, the Clipper 1736!" indicated that Captain Grubbs and First Officer Bragg had recognised the ambiguity;
- if the Pan Am aircraft had not taxied beyond the third exit, the collision would not have occurred.
Speculations
Speculation regarding other contributing factors includes:- Captain Van Zanten's failure to confirm instructions from the tower. The flight was one of his first after spending six months training new pilots on a flight simulatorFlight simulatorA flight simulator is a device that artificially re-creates aircraft flight and various aspects of the flight environment. This includes the equations that govern how aircraft fly, how they react to applications of their controls and other aircraft systems, and how they react to the external...
, where he had been in charge of everything (including simulated ATC), and having been away from the real world of flying for extended periods. - The flight engineer's apparent hesitation to challenge Van Zanten further, possibly because Captain Van Zanten was not only senior in rank, but also one of the most able and experienced pilots working for the airline.
- A study group put together by the Air Line Pilots AssociationAir Line Pilots Association, InternationalThe Air Line Pilots Association, International , is the collective bargaining representative for over 59,000 pilots of 39 U.S. and Canadian airlines. ALPA was formed in 1931 and is a member of the AFL-CIO and the Canadian Labour Congress...
found that not only the captain, but the first officer as well dismissed the flight engineer's question. In that case, the flight engineer might have been either reassured or even less inclined to press the question further.
- A study group put together by the Air Line Pilots Association
- The reason only the flight engineer reacted to the radio transmission "Alpha one seven three six report when runway clear" might lie in the fact that this was the first and only time the Pan Am was referred to by that name. Before that, the plane was called "Clipper one seven three six". The flight engineer, having completed his pre-flight checks, might have recognized the numbers but his colleagues, preparing themselves for take-off, might have subconsciously been tuned in to "Clipper".
- The extra fuel the KLM plane took on added several factors:
- it delayed takeoff an extra 35 minutes, which gave time for the fog to settle in;
- it added over forty tons of weight to the plane, which made it more difficult to clear the Pan Am when taking off;
- it increased the size of the fire from the crash that ultimately killed everyone on board.
- Captain Van Zanten's reaction, once he spotted the Pan Am plane, was to attempt to take off. Although the plane had exceeded its V1 speedV speedsIn aviation, V-speeds are standard terms used to define airspeeds important or useful to the operation of all aircraft including fixed-wing aircraft, gliders, autogiros, helicopters, and dirigibles...
, it did not yet have adequate airspeed. The sharp lifting angle caused the KLM jet to drag its tail on the runway, thereby reducing its speed even further.
Responsibility
Although the Dutch authorities were initially reluctant to blame Captain Van Zanten and his crew, the airline ultimately accepted responsibility for the accident. KLM paid the victims or their families compensation ranging between $58,000 and $600,000. As reported in a March 25, 1980, Washington Post article the sum of settlements for property and damages was $110 million (an average of $189,000 per victim, due to limitations imposed by European Compensation Conventions in effect at the time).Safety response
As a consequence of the accident, sweeping changes were made to international airline regulations and to aircraft. Aviation authorities around the world introduced requirements for standard phrasesVoice procedure
Voice procedure includes various techniques used to clarify, simplify and standardize spoken communications over two-way radios, in use by the military, in civil aviation, police and fire dispatching systems, citizens' band radio , etc....
and a greater emphasis on English as a common working language
Lingua franca
A lingua franca is a language systematically used to make communication possible between people not sharing a mother tongue, in particular when it is a third language, distinct from both mother tongues.-Characteristics:"Lingua franca" is a functionally defined term, independent of the linguistic...
. For example, ICAO
International Civil Aviation Organization
The International Civil Aviation Organization , pronounced , , is a specialized agency of the United Nations. It codifies the principles and techniques of international air navigation and fosters the planning and development of international air transport to ensure safe and orderly growth...
calls for the phrase "line up and wait" as an instruction to an aircraft moving into position but not cleared for takeoff. Also several national air safety boards began penalizing pilots for disobeying air traffic controllers' orders. Air traffic instruction should not be acknowledged solely with a colloquial phrase such as "OK" or even "Roger
Voice procedure
Voice procedure includes various techniques used to clarify, simplify and standardize spoken communications over two-way radios, in use by the military, in civil aviation, police and fire dispatching systems, citizens' band radio , etc....
", but with a readback of the key parts of the instruction, to show mutual understanding. Additionally, the phrase "takeoff" is only spoken when the actual takeoff clearance is given. Up until that point, both aircrew and controllers should use the phrase "departure" in its place (e.g. "ready for departure"). Cockpit procedures were also changed. Hierarchical relations among crew members were played down. More emphasis was placed on team decision-making by mutual agreement. This is known in the industry as Crew Resource Management
Crew Resource Management
Crew resource management or Cockpit resource management is a procedure and training system in systems where human error can have devastating effects. Used primarily for improving air safety, CRM focuses on interpersonal communication, leadership, and decision making in the cockpit...
.
In 1978 a second airport was inaugurated on the island: the new Tenerife South Airport
Tenerife South Airport
Tenerife South Airport , previously known as Tenerife South-Reina Sofia Airport, is one of two international airports located on the island of Tenerife, the largest of the Canary Islands . Between its opening and the end of 2006, a total of 173,912,207 passengers passed through the airport...
(TFS). This airport now serves the majority of international tourist flights. Los Rodeos, renamed to Tenerife North Airport (TFN), was then used only for domestic and inter-island flights, but in 2002 a new terminal was opened and it carries international traffic once again, including budget airlines. The Spanish authorities installed a ground radar at Tenerife North following the accident.
Memorials
Amsterdam
Amsterdam is the largest city and the capital of the Netherlands. The current position of Amsterdam as capital city of the Kingdom of the Netherlands is governed by the constitution of August 24, 1815 and its successors. Amsterdam has a population of 783,364 within city limits, an urban population...
, at Westgaarde cemetery. There is also a memorial at the Westminster Memorial Park and Mortuary in Westminster, California
Westminster, California
-Government:In the state legislature Westminster is located in the 34th, Senate District, represented by Democrat Lou Correa and Republican Tom Harman respectively, and in the 67th and 68th Assembly District, represented by Republicans Jim Silva and Van Tran respectively...
.
The 30th anniversary marked the first time that Dutch and American next of kin, and aid helpers from Tenerife, joined in international commemoration service held at the Auditorio de Tenerife in Santa Cruz; the International Tenerife Memorial March 27, 1977
International Tenerife Memorial March 27, 1977
The International Tenerife Memorial March 27, 1977 was erected in memory of the 583 victims of the Tenerife airport disaster is located on the Mesa Mota park on the outskirts of the city of San Cristóbal de La Laguna on the island of Tenerife .On March 27, 2007 the monument was inaugurated in Mesa...
was inaugurated at the Mesa Mota March 27, 2007. The monument was designed by Dutch sculptor Rudi van de Wint. A special 50-page commemorative booklet including a DVD in English, Dutch, and Spanish was published a year later, on March 27, 2008.
Notable victims
- Eve MeyerEve MeyerEve Meyer was an American pin-up model, motion picture actress, and later, film producer...
, a pin-up model, film actress and producer and former wife of Russ MeyerRuss MeyerRussell Albion "Russ" Meyer was a U.S. motion picture director, producer, screenwriter, cinematographer, editor, actor and photographer....
. - A. P. HamannA. P. Hamann-External links:**...
, the former city manager of San Jose, CaliforniaSan Jose, CaliforniaSan Jose is the third-largest city in California, the tenth-largest in the U.S., and the county seat of Santa Clara County which is located at the southern end of San Francisco Bay...
, and his wife Frances Hamann.
Documentaries
The disaster has featured in many TV shows and documentaries. These include Crash of the Century, the Survival in the SkySurvival in the Sky
Survival in the Sky is a series of six one-hour episodes produced by Darlow Smithson Productions for The Learning Channel and Channel 4. Narrated by Will Lyman or Sean Barrett , the series primarily concentrated on commercial aviation accidents and the investigations related to them...
episode Blaming the Pilot, the Seconds From Disaster
Seconds From Disaster
-By original broadcast date:National Geographic Channel has broadcast many episodes under multiple titles. The title currently or most recently listed on the NGC Calendar is shown first...
episode Collision on the Runway, PBS's NOVA
NOVA (TV series)
Nova is a popular science television series from the U.S. produced by WGBH Boston. It can be seen on the Public Broadcasting Service in the United States, and in more than 100 other countries...
episode "The Deadliest Plane Crash" in 2006, and the Discovery Channel
Discovery Channel
Discovery Channel is an American satellite and cable specialty channel , founded by John Hendricks and distributed by Discovery Communications. It is a publicly traded company run by CEO David Zaslav...
TV series Most Deadly and Destroyed In Seconds
Destroyed In Seconds
Destroyed in Seconds is a half-hour American television series that airs on Discovery Channel. Hosted by Ron Pitts, it features video segments of various things being destroyed fairly quickly such as planes crashing, explosions, sinkholes, boats crashing, fires, race car incidents, floods, etc....
.
See also
- Linate Airport disasterLinate Airport disasterThe Linate Airport disaster occurred on 8 October 2001 at Linate Airport in Milan, Italy, when Scandinavian Airlines Flight 686, a McDonnell Douglas MD-87 airliner carrying 110 people bound for Copenhagen, Denmark, collided on take-off with a Cessna Citation CJ2 business jet carrying four people...
, a runway collision that occurred in Milan in 2001 - List of accidents and incidents on commercial airliners grouped by year
- National Geographic Seconds From Disaster episodes
- Television series, Mayday
- Dan-Air Flight 1008Dan-Air Flight 1008Dan-Air Flight 1008 was a Boeing 727-46 that crashed on the 25 April 1980 while on approach to Tenerife North Airport, Canary Islands, Spain, at the end of a charter flight from Manchester. The aircraft flew into high terrain when it turned the wrong way in a holding pattern. The aircraft was...
, a fatal accident that occurred on approach to Tenerife North Airport in 1980
External links
- Final reports from Spanish authorities and commentary from Dutch authorities
- "KLM, B-747, PH-BUF and Pan Am, B-747, N736, collision at Tenerife Airport, Spain, on 27 March 1977." (Archive) - Subsecretaría de Aviación Civil, Spain. Distributed by ICAO circular - With comments from the Netherlands Aviation Safety Board in English
- "A-102/1977 y A-103/1977 Accidente Ocurrido el 27 de Marzo de 1977 a las Aeronaves Boeing 747, Matrícula PH-BUF de K.L.M. y Aeronave Boeing 747, matrícula N736PA de PANAM en el Aeropuerto de los Rodeos, Tenerife (Islas Canarias)." - Hosted by the Civil Aviation Accident and Incident Investigation CommissionCivil Aviation Accident and Incident Investigation CommissionThe Civil Aviation Accident and Incident Investigation Commission is the Spanish national agency responsible for air accident investigation. It is a division of the Ministry of Public Works and Transport...
- Comments from Netherlands Aviation Safety Board (Archive)
- Comments from Netherlands Aviation Safety Board (Archive)
- Report of Air Line Pilots Association, InternationalAir Line Pilots Association, InternationalThe Air Line Pilots Association, International , is the collective bargaining representative for over 59,000 pilots of 39 U.S. and Canadian airlines. ALPA was formed in 1931 and is a member of the AFL-CIO and the Canadian Labour Congress...
(Archive) - "Ask The Pilot: A look back at the catastrophic chain of events that caused history's deadliest plane crash 30 years ago." by Patrick Smith, Salon.com, April 6, 2007
- AirDisaster.com Accident Database (Pan Am 1736)
- AirDisaster.com Accident Database (KLM 4805)
- ICAO document mentioning phrasing used in the accident
- Tenerife – a survivor’s tale, by Robert L. Bragg (Capt., Pan Am and United, Ret.)
- Secret Tenerife: On This Day in 1977: Runway Collision Kills 583, March 27, 2004
- Historic BBC news report
- PBS's: NOVA "The Deadliest Plane Crash" (2006) – Homepage to the NOVANOVA (TV series)Nova is a popular science television series from the U.S. produced by WGBH Boston. It can be seen on the Public Broadcasting Service in the United States, and in more than 100 other countries...
TV episode 3 of season 34 - International Tenerife Memorial
- Project Tenerife
- List of passengers on the Pan Am
- List of passengers on the KLM
- PlaneCrashInfo.Com – Tenerife Disaster
- "There he is...look at him!" he cried out. "Goddamn...that son-of-a-bitch is coming" (On-line copy of chapter 18 of Air Disaster, Volume 1 by Macarthur Job)