Template:Crash frame Template:Crash title Template:Crash infobox Template:Aircraft title Template:Aircraft infobox Template:Aircraft infobox Template:End frame The Tenerife disaster took place at 17:06 local time on March 27, 1977, when two Boeing 747 airliners collided on the island of Tenerife, killing 583 people. The incident was the deadliest aircraft disaster in history until the September 11, 2001 attacks. It is noteworthy that one of the aircraft was on the ground when the collision occurred.
On March 26, 1977 Pan Am Flight 1736, under the command of captain Victor Grubbs, had taken off from Los Angeles International Airport, bound for the Canary Islands, with an intermediate stop at New York's JFK International Airport. The aircraft was a B-747-121, registration N736PA and named Clipper Victor. This aircraft happened to have been the first 747 to carry fare-paying passengers, on a flight from New York to London on 21 January 1970.
KLM Flight 4805, named Rijn (Rhine River), a charter flight full of vacationers from the Netherlands, had taken off four hours ago from Schiphol airport, and was under the command of captain Jacob Veldhuyzen van Zanten.
Terrorist bomb threat
Upon approaching its final destination, Las Palmas, the Clipper Victor was told that the major airport was temporarily closed due to a terrorist bomb attack by Canary Island separatists. Although Clipper Victor had indicated that it would preferably circle until landing clearance was given, it was ordered to divert to Los Rodeos airport on the neighboring island of Tenerife, together with many other planes. It landed at Tenerife and, after the authorities reopened Las Palmas, was waiting to go. 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, which 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.
Chain of events leading to disaster
The Pan Am jet was ready to taxi and depart, but it was blocked by the KLM plane and a refueling vehicle. Captain van Zanten had decided that it would spare time refueling here, instead of Las Palmas. Once refueling was done, the KLM plane was to take off first, followed by the Pan Am plane.
Taxiing and weather conditions
Following the tower's instructions, the KLM jet taxied to the end of the main runway, made a 180 degree turn (in aviation terms this is called a 'backtrack' and is difficult with a 747 on the narrow runway) and waited for ATC-clearance from air traffic control. During taxiing, low clouds had appeared, limiting the visual range to 1000 feet (approx. 300 meters).
With KLM ready to go, 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 a parallel taxiway. After reaching exit C3, the crew noticed that the aircraft would have to make a 135º turn onto the exit and a 135º 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 45º .
Tenerife ATC gave the KLM-flight its ATC-clearance, a clearance to fly a certain route immediately after take-off (This is not a clearance to begin take-off), but the KLM captain apparently mistook this to be permission for the takeoff 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 ). The control tower was confused with the message and asked for the KLM plane to stand by. However, simultaneous communication from Pan Am caused a heterodyne, making the response inaudible. Ironically, Pan Am was reporting they had not finished taxiing. Either message, if broadcast separately, might have given KLM 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 747s could be seen from the control tower, and the airport was not equipped with runway radar.
While the KLM 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, but was overruled by the captain. 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.
|image (impression) of collision
image (impression) of the fatal collision
Captain Grubbs of the Pan Am spotted the KLM's landing lights just as the plane approached exit C4, and is recorded on CVR exclaiming "There he is! Look at him! Goddamn ... that son of a bitch is coming! Get off! Get off! Get off!" ten seconds before the collision. The Pan Am's pilots tried to apply full power and took a sharp left turn onto the exit, but the collision was only seconds away. 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), but was only slightly airborne at the time of impact. 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 (321 passengers and 14 crew members) perished, primarily due to the fire and explosions resulting from the fuel spilled in the impact (the KLM plane had been fully fueled). The Pan Am captain was among the survivors (54 passengers and 7 crew members).
Later investigation showed that there had been misinterpretations and false assumptions. Analysis of the cockpit voice recorder (CVR) transcript shows 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. While there is debate about their relative importance, the general conclusion is that the disaster was caused partly by 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), partly by non-standard phrases used by the KLM co-pilot ("We're at take off") and the Tenerife control tower ("O.K."), and partly by the Dutch captain van Zanten seemingly being in a hurry to commence the delayed flight, possibly due to Dutch regulations on exceeding crew duty hours.
This was difficult to accept for the investigators, as 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 as an instructor at a pilot training simulator, and some experts claim in time he might have developed some kind of governance attitude though being in charge of everything at the simulator, which is another reason suggested for van Zanten not confirming the instructions from the tower.
Changes in airline regulations
About 70 crash investigators from Spain, the Netherlands, the US, and the two airline companies were involved in the investigation. 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. 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.
Los Rodeos now
- Report from Pan Am Accidents site
- Coverage from Air Safety Network site (Pan Am 1736)
- Coverage from Air Safety Network site (KLM 4805)
- Project-tenerife, site about this accident
- History of the 747 website, with a section on the CVR transcript and analysis of the crash
- ICAO document mentioning phrasing used in the accident