On Sunday 27 March 1977, just after 5:00 PM, two 747 jumbo jets collided during take-off on the runway of Los Rodeos Airport in the Canary Islands off the Spanish coast. The collision caused a massive explosion and both aircraft were engulfed in flames. The Tenerife airport disaster remains the deadliest crash in aviation history.
Despite the devastating impact and resulting fire, there were some survivors. Of the 644 people on board the two planes, 583 were killed and 61 somehow managed to survive. The crash of a single passenger airplane is bad enough. How could two 747’s have collided on the same runway? Nearly a dozen mistakes and uncontrollable events lined up for the disaster to occur. The pilots of both planes were experienced, but they both made critical errors that led to the horrific tragedy.
The KLM Flight 4805 from Amsterdam to Gran Canaria was flown by Captain Jacob Veldhuyzen van Zanten and First Officer Klaas Meurs. It carried 14 crew and 234 passengers on departure from Tenerife. The Pan Am Flight 1736 from New York JFK to Gran Canaria was piloted by Captain Victor Grubbs and First Officer Robert Bragg. It carried 16 crew and 380 passengers.
Ironically, neither of the planes should have even been at Tenerife, let alone on the same runway at the same time. So how did the Tenerife airport disaster happen? Both 747’s were carrying passengers heading towards vacations on Grand Canary Island. That Sunday morning, shortly before the arrival of the two jumbo jets, a terrorist group set off a bomb in Grand Canary’s Las Palmas Airport terminal.
A telephoned threat made reference to “bombs,” so all incoming flights were postponed or diverted.
While the search for a second bomb was carried out, incoming aircrafts, including the Pan Am and KLM 747’s were diverted. They landed at nearby Tenerife Los Rodeos Airport to wait until Las Palmas officials gave the all-clear. The search took hours and hundreds of buckled-in passengers now stuck in Tenerife became impatient.
The much smaller Los Rodeos Airport had only one runway, one parallel taxiway, and limited space for aircraft. The diverted aircraft had to park on the taxiway, meaning departing aircraft had to taxi into position around them using the runway. Only two Air Traffic Controllers were on duty, and they had to handle much more traffic than either had ever seen.
Trying not to jam up the airport’s small terminal building, Pan Am Captain Grubbs kept the 380 passengers and 13 crew on board while they waited. After an hour or so, Grubbs invited anyone on board to have a look in the 747’s cockpit. Dozens of curious and bored passengers eagerly accepted the offer. A line of people extended through the second-floor lounge, down a circular stairway into the first-class section.
“They ordered us down without saying why,” Grubbs told frustrated passengers. “We told them that we could remain in a holding pattern above Las Palmas because we had plenty of fuel.” If Pan Am had been allowed to stay in a holding pattern, the ensuing accident would never have happened.
In the KLM plane, Captain Van Zanten had let their 234 passengers leave the airplane and wait in the small Tenerife terminal. While they waited, the KLM cockpit crew worried aloud about their Dutch government’s strict rules limiting overtime for flight crews. Their continuing flight from Grand Canary back to Amsterdam would push that limit. “It could mean serious fines and even a revocation of your pilot’s license,” Captain van Zanten explained to his cockpit crew.
The KLM captain then decided to use the time waiting at the terminal to refuel his plane so he would not have to later at Gran Canary. It was a decision that would later prove disastrous. Just after the refueling began, the tower informed them that Las Palmas airport had reopened. But now, KLM had to wait for the fuel truck to finish.
Several smaller passenger jets were able to taxi around the KLM 747 and onto the runway and leave Tenerife. But Pan Am, parked behind KLM on the apron was too large and had to wait as well. And with the extra fuel, KLM had become thousands of pounds heavier, meaning it would need more runway to get off the ground. Another factor that would prove disastrous in a few minutes.
KLM terminal staff rounded up all the passengers and bused them back to the waiting plane. Meanwhile, an evening fog rolled in and the visibility throughout the Tenerife airport quickly worsened. Los Rodeos Airport frequently suffered from foggy conditions. Drifting clouds reduced the visibility to less than 100 meters (110 yards) on the runway.
In addition to the crew’s visibility, the fog affected the tower’s view as well.
Shortly before 5 PM, the control tower gave KLM permission to start its engines and gave them take-off instructions. They were to taxi and enter the runway at the northwest end, move down the runway, and leave it at exit turnoff C-3 for the adjacent taxiway. From there it could continue to the southeast end of the taxiway, swing back onto the runway, then wait for its final takeoff run back to the northwest. The Pan Am 747 also started its engines, and the tower gave them the same instructions, following behind the KLM plane.
But that’s not what happened. Both cockpit crews got confused about the runway exit they were supposed to take. Neither crew was sure which exit the ground controller had told them to take. C-3 required a difficult maneuver. They would have to turn their huge 747’s 135 degrees to the left to get onto C-3, then turn 135 degrees to the right to get on the taxiway. By comparison, the C-4 turnoff was only a 45 degree turn.
After several back and fourths between KLM and the tower seeking clarity, the airport traffic controller changed his mind. At 4:56 PM, the tower gave the KLM aircraft clearance to taxi the length of the runway and do a 180-degree turn, so that the jet was then facing the direction for take-off.
The KLM crew did as directed, going to the end the runway and completed their turn. In the meantime, the Pan Am 747 was entering the runway on the other end as KLM just had. At 5:02 PM, the Pan Am aircraft was instructed to start its taxi along the runway and exit at C-3. As with KLM, the Pan Am crew was confused. Grubbs and Bragg had trouble believing they weren’t supposed to leave at C-4.
The Pan Am aircraft did not take the third exit, which would have required the two sharp turns and continued to taxi along the runway towards C-4. Copilot Bragg later said the fog was so heavy that they taxied past C-3 without noticing it. The two jumbo jets were now facing each other on the same runway at opposite ends, but unable to see each other through the fog.
Tenerife air traffic controllers could not see the runway and had no ground radar.
At 5:06 PM, the tower gave KLM departure and routing instructions but not takeoff clearance. KLM 4805 read this back and finished with, “We are now at takeoff.” The response from the tower was, “Stand by for takeoff. I will call you.” The KLM crew likely missed part of this critical communication due to radio interference.
At the same time, the Pan Am crew radioed, “We’re still taxiing down the runway, Pan Am 1736.” The overlap in these two messages led to the KLM crew not hearing the critical tower instructions. That transmission should have been audible in KLM’s cockpit, but instead an electronic buzz, or heterodyne, interfered with the transmission. The KLM 747 began its take-off run!
Oblivious to this series of unfortunate events, the passengers inside each plane were adjusting seat backs, putting away personal items and getting ready for the short hop over to Las Palmas. After a several-hour delay, the passengers were finally getting ready to take off to their vacations.
Just as Pan Am passed C-3, KLM’s captain took the action that sealed everyone’s fate: He began his takeoff roll before getting permission from the controller. First officer Klaas Meurs was still finishing a radio confirmation with the tower of their post-takeoff flight instructions. At 5:06 pm, Captain van Zanten released the brake, pushed the throttles, and began accelerating down the runway.
“Stand by for takeoff. I will call you,” the controller had said to him. Apparently van Zanten heard only the word “takeoff.” Yet, even with van Zanten’s decision to begin, there was still one last opportunity to avoid the collision. The flight engineer did not like what he thought he’d heard on the radio. “Is Pan Am still on the runway?” he asked van Zanten, as KLM picked up speed.
Captain Van Zanten apparently didn’t hear him, and seconds ticked by. “What did you say?” the pilot asked. “Is he not clear, the Pan American?” More seconds ticked by. “Oh … yes” van Zanten responded. The last words recorded in the KLM cockpit, just before the rash at 5:07 pm, were a shouted Dutch swear word, when Pan Am suddenly appeared through the fog still taxiing in front of them, “Godverdomme!”
The Pan Am 747 jumbo jet was moving slowly down the runway when the passengers felt a sudden sharp swerve to the left, heading off the runway. Captain Grubbs and first officer Bragg had just seen the KLM 747 speeding through the fog directly toward them. Grubbs tried desperately to get out of the way, heading into the grass next to the runway. They did not make it.
Captain Van Zanten pulled back hard on the yoke and added power in a unsuccessful attempt to take-off and clear the Pan Am 747. Just refueled, the plane was too heavy for such a maneuver. The nose rose in the air and the plane’s tail carved a 68-foot groove in the runway.
The ensuing collision and the jet fuel firestorm that followed killed everyone on board KLM 4805.
The KLM struck the Pan Am 747 at an angle because of that emergency left turn by Captain Grubbs. Some sections of the 747 weren’t as damaged as those that took the full impact of KLM’s fuselage. After both planes came to a rest in pieces, around 100 Pan Am passengers were alive. What followed was a hellish few minutes of evacuation by some of the passengers, and a shocked immobility by others.
The situation inside Pan Am 1736 required immediate escape as fires and smoke filled the cabin. The first people to respond, other than the crew members, were those who had looked at the safety cards and understood the cabin’s layout. Passengers made their way to the exits, only to find that no slides were available because the side of the plane had been ripped apart in the collision. They had no choice but to leap 20 feet down to the runway.
Several less-injured passengers climbed up through a hole in the ceiling, then down to the undamaged left wing. The scene outside was pure chaos. Huge orange flames and massive black smoke roared up from the destroyed Pan Am. The KLM wreckage was burning 400 yards down the runway. Pan Am’s crew and four surviving flight attendants did their best to guide passengers to safety. The Airport immediately launched rescue efforts to save the survivors.
At least 71 people on board the Pan Am plane were able to get away from the burning fuselage. However, several later died of their injuries. Only 61 people survived. The collision and explosion instantly claimed the lives of the 248 passengers and crew on KLM Flight 4805, as well as 335 passengers and crew members on Pan Am Flight 1736.
Following the Tenerife airport disaster, an investigation was conducted to determine the cause. It was found that a series of miscommunications and misunderstandings among the air traffic controllers and pilots contributed to the tragedy. Poor visibility due to the fog also played a role. Los Rodeos Airport was ill-prepared to handle such a large number of diverted aircraft. The investigation revealed that KLM pilot Captain Jacob Veldhuyzen van Zanten made a critical error in attempting to take off without proper clearance.
The investigation highlighted the importance of effective communication and coordination between air traffic controllers and pilots, as well as the need for improved runway safety protocols. As a result, numerous changes were made to international aviation regulations and procedures.
These changes included improved communication systems, increased training for pilots and air traffic controllers, new protocols for responding to adverse weather conditions, an expansion of runway traffic light systems. In the years after the Tenerife airport disaster, the island’s government completed a new airport—this one with ground radar.
A memorial to honor the victims is the Tenerife Memorial Gardens, located in Los Rodeos Airport, near the site of the collision. It features a tall monument with the engraved names of all the victims. Every year, on March 27th, ceremonies are held there to commemorate the Tenerife airport disaster and honor the memory of those who tragically lost their lives.