It was past five in the afternoon and the dense fog enveloped the Los Rodeos airport in Tenerife. The explosion of a bomb at the Gran Canaria airport had forced air traffic to be diverted to this other location, smaller than that of the neighboring island.
The Canarian airfield reopened, two Boeing 747s, one from the Dutch company KLM with 234 passengers and 14 crew members on board, and the other from the American Pan Am, with 378 passengers and 16 crew members, were preparing to fly to the Canarian airport. But that March 27, 1977, neither of the two jumbos it would reach its destination.
A concatenation of factors resulted in the collision of both aircraft on the runway, which caused the largest plane crash in history, with a total of 583 fatalities. The technical report of the Accident Investigation Commission blamed the KLM commander, Jacob Velthuyzen van Zauten (one of the deceased), for taking off without having a green light from the control tower.
“The final cause, the most serious of the errors, was the decision to take off without authorization by van Zauten, but the accident can only be analyzed taking into account the other factors that occurred”, reminds EL ESPAÑOL José Puga, Secretary of Training of the Union of Air Traffic Controllers (USCA).
Communications interference, dense fog and an airport at capacity limits are three of the factors that contributed to the catastrophe. Forty years later, the experts consulted by this newspaper agree that flying today is much safer, as technological, training and procedural improvements have been developed.
On a day like today, it is inevitable to wonder if an accident of these characteristics could happen again. “It’s very complicated,” says Ariel Shocron, president of the Spanish Association of Commercial Civil Pilots (AEP). Although some collisions between planes were repeated after what happened in Los Rodeos – such as the 1983 Barajas accident in which 93 people died -, today, the collision between aircraft is not statistically significant for researchers.
Both pilots, controllers and engineers emphasize that, despite the increase in air traffic, the accident rate has not stopped decreasing. If in 2008 there were 4.8 accidents for every million departures, in 2015 the figure dropped to 2.8 accidents, according to the latest data from the International Civil Aviation Organization (ICAO). The five breakthroughs we review below have made flying safer today than it was in the 1970s.
Lower hierarchy in the cabin
“At that time the great commanders were those who reigned and those who were in command. The co-pilots were just there to help them, ”says Shocron, who is also the technical director of SEPLA, the Spanish Union of Airline Pilots. This highly hierarchical quasi-military culture was largely responsible for the Los Rodeos accident.
Despite the fact that the copilot and the KLM flight mechanic understood that the control tower was not authorizing them to take off and thus informed the captain, van Zauten misinterpreted the order and began the maneuver.
“They didn’t tell him proactively, they just told him that they believed they were not authorized. That’s when the commander applies power and decides to take off ”, says the pilot.
As a result of the accident, the relationships that existed in the cockpit were studied to try to end that hegemony that the commanders had and put an end to the martial culture of ‘command and control’. Thus, the concept of CRM – crew or cabin resource management, according to its acronym in English – was born, which is based on joint decision-making and teamwork.
“It focuses on interpersonal communication training, leadership and decision-making in the cockpit, where human error can have tragic effects. It has been revealed as a key safety factor in aviation ”, assures EL ESPAÑOL Alejandro Herrera, secretary of the Board of Directors of the Official College of Aeronautical Engineers of Spain (COIAE).
Although the captain continues to have the last word, decisions are now made jointly and the voice of the co-pilot carries more weight than before.
The investigation that was launched after the tragic accident at the Tenerife airport revealed serious interference in communications, which contributed to the fatal outcome. These crossovers in messages occur when several communications are made at the same time and a coupling occurs on the radio frequency.
Although today communications have improved a lot, both in power –with a greater number of frequencies– and in clarity –with headphones that attenuate noise– “the problem of simultaneous emission from two sources still persists”, emphasizes Puga. To solve this problem, nowadays all control authorization must be clearly repeated by the aircraft.
In addition, a set of standard sentences has been implemented that makes it easy to understand them even when there are noises. “In other words, pre-established short phrases are used and known by all the people involved for each information that is given, instead of doing it with freely composed expressions as before,” Herrera declares.
Another tool aimed at improving the quality of communications is the data link, with which authorizations and other types of messages are made through data transmission, not voice, and which requires continuous surveillance by both the air traffic controller and the pilot.
In addition to these devices, the linguistic competence of pilots today is much higher than that of forty years ago. “Since 2008 we have to prove knowledge of the language used in commercial air operations, which for international operations is English,” say sources from the Official College of Commercial Aviation Pilots (COPAC).
In this way, the International Civil Aviation Organization established six levels of knowledge. “The pilots must accredit at least operational level four and examine ourselves periodically to guarantee an adequate use of the language in terms of comprehension, fluency, vocabulary or interaction,” they indicate from COPAC. In addition to the pilots, depending on each specific position, the crew will have to meet one level or another of language proficiency, which will also be evaluated periodically.
There is no question in the airline industry: the airplanes in the skies today are much safer than those of the 1970s. Common technologies such as status and parameter monitoring of on-board systems, or automatic in-flight collision avoidance forty years ago did not even exist.
This is the case of TCAS, a system with which the teams of two or more aircraft contact each other to avoid collisions. “It is a reliable system that ultimately requires the participation of the pilot to follow the instructions of the team on board”, emphasizes Puga. Unfortunately, in the accident over Lake Constance (Germany) that occurred on July 1, 2002 at an altitude of 11,000 meters and in which 71 people died, “one of the two aircraft involved did not follow the instructions given by the TCAS. ”Adds the air traffic controller.
Inside the cockpit, the hands and clocks have given way to more sophisticated technological elements, increasing reliability and safety. To this must be added that Security Management Systems have been introduced.
“They have favored operational safety to be assumed as one more process that must be managed in an organization, with policies, processes and lines of responsibility that have led to an improvement in the management of such an important value for the sector,” they point out from COPAC.
Parallel to the advances in aircraft, on the ground, airports have been implementing a series of innovations aimed at improving security. Today, for example, the position of any vehicle on the tracks is known exactly thanks to rolling radars. “Some small devices emit a code and the controller is able to see who is and where at any time, with an identification number,” reports Shocron.
Along the same lines, there are lighting systems that are capable of detecting if someone is on the track through photoelectric sensors. “If there is a conflict due to an occupied runway, red lights are turned on along its entire axis to alert the pilot,” they detail from COPAC.
In addition, to minimize the risk of systems crashing in the control tower, both radar and radio, the equipment with which the air traffic controllers work has been doubled. Both they and the drivers have much more information about what happens on the track. “Conflict detection systems have been incorporated that help to make decisions in advance and reduce the level of workload,” says Puga.
The closed fog that spread over the Tenerife airport the morning of the accident was another factor that led to the catastrophe. Neither the pilots of the two jumbos not even the controllers had sufficient visibility to appreciate what was about to happen.
Today, advances in aeronautical engineering have ensured that fog and other adverse atmospheric phenomena do not compromise flight safety. “As a result of the Los Rodeos accident, automatic navigation methods began to be installed in the planes to allow them to move in fog,” Herrera points out. In addition, ground radars, which until then only existed on runways in large cities – which ruled out small airports such as Tenerife -, began to be included in more facilities.
Shocron is used to dealing with elements like fog. “Low visibility approach systems have improved a lot and allow us to make fully automatic landings with zero visibility,” he asserts. Regarding take-off, although the minimum restriction is that there is at least 125 meters of visibility, in his opinion the conditions have improved a lot and all the indications in the cabin are more reliable.