Studi Kasus


Semoga dengan adanya beberapa kasus yang kami tampilkan di bawah ini dapat menjadi masukan positif sekaigus meningkatkan awareness kita dalam melaksanakan tugas dan tanggung jawab kita sebagai ATC profesi yang kita cintai ini…  be safe guys..

Tenerife disaster

From Wikipedia, the free encyclopedia

Tenerife disaster

Tenerife disaster The accident has the highest number of fatalities (excluding ground fatalities) of any single accident in aviation history. It occurred as a result of a synchronicity of a chain of events, any one of which having not transpired would have prevented the accident.

The aircraft involved were Pan American World Airways Flight 1736, named Clipper Victor, under the command of Captain Victor Grubbs, and KLM Royal Dutch Airlines Flight 4805, named Rijn (Rhine River), under the command of Captain Jacob Veldhuyzen van Zanten. KLM 4805, taking off on the only runway of the airport, crashed into the Pan Am aircraft which was taxiing in the opposite direction on the same runway.

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

Flight details

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. Of the 380 passengers, 14 had boarded in New York City. The crew was changed at New York. The new captain was Victor Grubbs, and the first officer was Robert Bragg. There were 14 other crew members.[1]

KLM Flight 4805, a charter flight for Holland International Travel Group from the Netherlands,[1] had taken off four hours before from Amsterdam Schiphol Airport. The aircraft was a Boeing 747-206B, registration PH-BUF. The KLM had 235 passengers and 14 crew members. 48 children and three babies were among the passengers. Most of the KLM passengers were Dutch; four Germans, two Australians, and two Americans were also on the plane. After the aircraft was grounded at Tenerife, a tour guide named Robina van Lanschot, who lived on the island and wanted to see her boyfriend that night, elected not to reboard the 747, leaving 234 passengers on the KLM.[2][3]

The destination of both planes was Las Palmas on Gran Canaria. Events on both planes were routine until they approached the Canary Islands, in the Atlantic Ocean off the west coast of Spain.

Bomb threat

At 1:15 PM on March 27, 1977, in the Las Palmas Airport, a small bomb planted by a terrorist exploded in a florist’s shop on the terminal concourse. Airport authorities had been warned of the blast 15 minutes before, so although the bomb damaged the inside of the terminal, the building was being evacuated at the time and there were no fatalities. However, eight people were injured, one seriously. Later, another telephone call was received claiming responsibility for the explosion and hinting that a second bomb was planted somewhere in the terminal building. The civil aviation authorities at Las Palmas closed the airport pending a thorough search for the second bomb. This necessitated the diversion of incoming flights, including a number of large aircraft on long international flights.[4]

Upon contacting Gran Canaria International Airport, the Pan Am flight was told that the airport was temporarily closed due to a bomb attack, supposedly by Canary Islands separatists. Although the Pan Am crew indicated that they would prefer to circle until landing clearance was given, the plane was ordered to divert to Tenerife North Airport (Los Rodeos) on the nearby 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. While waiting for the 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.

Chain of events leading to disaster


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 refueling vehicle obstructed the way to the active runway. Captain Veldhuyzen van Zanten had decided to refuel at Los Rodeos instead of Las Palmas, apparently to save time. The refueling was to take an estimated 35 minutes.[2]

Taxiing and weather conditions

Following the tower’s instructions, the KLM aircraft was cleared to backtaxi to the end of the only runway and make a 180 degree turn to put the aircraft in takeoff position (a difficult maneuver to perform with a 747 on the narrow 150′ wide runway). While KLM 4805 was backtracking on the runway, the controller asked the flight crew to report when it was ready to copy the ATC clearance. 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 had limited the visual range to about 300 meters.

Shortly afterwards Pan Am 1736 was instructed to also backtaxi along the same runway and take the third exit on their left, leaving the main runway, and taxi via 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 using an airport diagram proceeded to identify the unmarked taxiways as they slowly reached them. Based on the chronology of the 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 (C-1) and second (C-2) taxiways but their discussion in the cockpit never indicated that they had identified the third (C-3) taxiway which they were instructed to use. The crew appeared to remain unsure of their position on the runway up until the collision which occurred near the intersection with the fourth taxiway (C-4).

Communication misunderstandings

Immediately after lining up, the KLM captain advanced the throttles slightly (a standard procedure known as spin-up to verify the engines are operating properly for takeoff) and the co-pilot advised the captain that ATC clearance had not yet been given. The captain responded “I know that. Go ahead, ask.” The co-pilot then radioed the tower that they were “ready for take-off” and “waiting for our ATC clearance”. The KLM crew then received a clearance which specified the aircraft’s departure route and gave instructions which stated what to do after take-off (the word take-off itself was part of the clearance); but not an explicit, distinct statement saying that they were cleared for take-off.

The KLM co-pilot read the clearance back to the controller completing the readback with the statement “we’re now at take-off” or “we’re now uh..taking off” (the exact wording of his statement was not clear) indicating to the controller that they were beginning their take-off roll.

The controller initially responded with “O.K.” (terminology which, although commonly used, is nonstandard), which the KLM crew heard clearly and reinforced their misinterpretation that they indeed had explicit take-off clearance. The controller’s response of “O.K.” to the co-pilot’s nonstandard statement that they were “now at take-off” was likely due to his misinterpretation that they were in take-off position, and ready to begin the roll when take-off clearance was received, but not actually in the process of take-off. The controller then immediately added “Stand by for take-off, I will call you”, indicating that the controller had never intended the clearance to be interpreted as a take-off clearance.

However, a simultaneous radio call from the Pan Am crew at that precise moment caused mutual interference on the radio frequency and all that was audible in the KLM cockpit was a heterodyne beat tone, making the crucial latter portion of the tower’s response inaudible to the KLM pilots. The Pan Am crew’s transmission, which was also critical, was reporting that they had not finished taxiing and were still on the runway. This message was also blocked by the heterodyne and inaudible to the KLM crew.

Either message, if broadcast separately, would have been audible in the KLM cockpit and given the KLM crew time to abort its take-off.

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 ground radar.

While the KLM crew had started its take-off roll, the tower instructed the Pan Am crew to “report when runway clear”. The 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 if the Pan Am was not clear. However, the captain, focused on the takeoff and under the impression that they had take-off clearance, replied yes emphatically and continued with the take-off.


Simplified map of runway, taxiways, and aircraft. The red star is the location of impact.

Simplified map of runway, taxiways, and aircraft. The red star is the location of impact.

According to the CVR, Captain Grubbs, captain of the Pan Am plane, spotted the KLM’s landing lights just as the plane approached exit C4. The Pan Am crew applied full power and took a sharp left turn onto the exit to avoid a collision. KLM Captain Veldhuyzen van Zanten 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 was briefly airborne, but the impact with the Pan Am had sheared off the #1 (leftmost) engine, and the #2 engine (inner starboard) had ingested significant amounts of shredded materials from the Pan Am. The KLM pilot quickly lost control, went into a stall, rolled sharply, and slammed into the ground at a point 150 m past the point of collision and slid a further 300 meters down the runway.

All 234 passengers and 14 crew members in the KLM plane were killed. 326 passengers and nine crew members aboard the Pan Am flight perished,[5] primarily due to the fire and explosions resulting from the fuel spilled in the impact. 56 passengers and five crew members aboard the Pan Am aircraft survived, including the Captain, First Officer, and Flight Engineer. Most of the survivors on the Pan Am aircraft were able to walk out onto the left wing through holes in the fuselage structure. At least one passenger stated that the 747’s engines were still running for a few minutes after the accident, which eventually threw out shrapnel that killed survivors stranded on the runway. Remaining 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 jumped to the ground below. The only member of the KLM passenger manifest to avoid the disaster was tour guide Robina van Lanschot, who had not reboarded the 747 when it was due to depart.[2]


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 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.

Probable cause

While there is disagreement about their relative importance, the investigation concluded that the major causal factors of the accident were:

  • KLM mistakenly took off without a take-off clearance.
  • Pan Am mistakenly continued to exit 4 instead of exiting at number 3 as directed by ATC.
  • Squelched radio messages (two calls between the planes and the control tower interfered with each other because they happened at precisely the same instant).
  • Use of ambiguous non-standard phrases by the KLM co-pilot (”We’re at take off”) and the Tenerife control tower (”O.K.”).
  • The airport, designed to handle smaller aircraft like the Boeing 737, was (due to rerouting from the bomb threat) forced to accommodate a large number of larger aircraft, resulting in disruption of the normal use of taxiways.


Experts speculated about other contributing factors:

  • Captain Veldhuyzen 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 simulator. He may have suffered from ‘training syndrome’, having been in charge of everything at the simulator (including simulated ATC), and having been away from the real world of flying for extended periods.[2]
  • The flight engineer’s apparent hesitation to further challenge Veldhuyzen van Zanten, possibly because Veldhuyzen van Zanten was not only senior in rank, but also one of the most able and experienced pilots working for the airline.[2]
  • The possibility that Veldhuyzen van Zanten was in a hurry to commence the delayed flight due to Dutch regulations on exceeding crew duty hours.[6]
  • There was disagreement between the various investigative bodies, with the Dutch investigators suggesting that during the incident the Spanish control tower crew had been listening to a soccer game on the radio and that the American crew was at fault for staying on the runway. Both the Spanish and Pan American investigations pointed the finger primarily at the KLM crew.[6]

Safety response

As a consequence of the accident, there were sweeping changes made to international airline regulations and to aircraft. 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. Additionally the phrase “take-off” is only spoken when the actual take-off 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 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.

In 1978 a second airport was inaugurated on the South of 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.


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