Diversion of aircraft to Los Rodeos Both flights had been routine until they approached the islands. At 13:15, a
bomb planted by the separatist
Canary Islands Independence Movement exploded in the terminal of Gran Canaria Airport, injuring eight people. Due to the threat of a second bomb, the civil aviation authorities closed the airport temporarily after the initial explosion, and all incoming flights bound for Gran Canaria were diverted to Los Rodeos, including the two aircraft involved in the disaster. The Pan Am crew indicated that they would prefer to circle in a
holding pattern until landing clearance was given (they had enough fuel to safely stay in the air for two more hours), but they were ordered to divert to Tenerife. Los Rodeos was a regional airport that could not easily accommodate all of the traffic diverted from Gran Canaria, which included five large airliners. The airport had only one
runway and one major
taxiway running parallel to it, with four short taxiways connecting the two. While waiting for Gran Canaria airport to reopen, the diverted planes took up so much space that they had to park on the long taxiway, making it unavailable for the purpose of
taxiing. Instead, departing aircraft needed to taxi along the runway to position themselves for takeoff, a procedure known as a
backtaxi or backtrack. The refueling took about 35 minutes, after which the passengers were brought back to the aircraft. The search for a missing Dutch family of four, who had not returned to the waiting KLM plane, delayed the flight even further. Additionally, Robina van Lanschot, a tour guide, had chosen not to reboard for the flight to Las Palmas, because she lived on Tenerife and thought it impractical to fly to Gran Canaria only to return to Tenerife the next day. She was therefore not on the KLM plane when the accident happened, and was the only survivor of those who flew from Amsterdam to Tenerife on Flight 4805.
Taxiing and takeoff preparations The tower instructed the KLM plane to taxi down the entire length of the runway and then make a 180° turn to get into takeoff position. Shortly afterward, the Pan Am was instructed to follow the KLM down the same runway, exit it by taking the third exit on the 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. The angle of the third taxiway would have required the plane to perform a 148° turn, which would lead back toward the still-crowded main
apron. At the end of C3, the Pan Am would have to make another 148° turn to continue taxiing toward the start of the runway, similar to a mirrored letter Z. Taxiway C4 would have required two 35° turns. A study carried out by the
Air Line Pilots Association (ALPA) after the accident concluded that making the second 148° turn at the end of taxiway C3 would have been "a practical impossibility". The official report from the Spanish authorities explained that the controller instructed the Pan Am aircraft to use the third taxiway because this was the earliest exit that they could take to reach the unobstructed section of the parallel taxiway. 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 shrill sound (or
heterodyne). This caused the KLM crew to miss the crucial latter portion of the tower's response. The Pan Am crew's transmission was "We're still taxiing down the runway, Clipper 1736!" This message was also blocked by the interference and inaudible to the KLM crew. Either message, if heard in the KLM cockpit, would have alerted the crew to the situation and given them time to abort the 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, as the airport was not equipped with
ground radar.
Collision According to the
cockpit voice recorder (CVR), the Pan Am captain said, "There he is!" when he spotted the KLM's landing lights through the fog just as his plane approached exit C4. When it became clear that the KLM aircraft was approaching at takeoff speed, Captain Grubbs exclaimed, "Goddamn, that son-of-a-bitch is coming!", while first officer Robert Bragg yelled, "Get off! Get off! Get off!" Grubbs applied full power to the throttles and made a sharp left turn toward the grass in an attempt to avoid the impending collision. instantly killing all of the passengers seated there. The KLM plane remained briefly airborne, but the impact had sheared off the No. 1 engine (outer left), caused significant amounts of shredded materials to be ingested by the No. 2 engine (inner left), and damaged the wings. The plane immediately went into a stall, rolled sharply, and hit the ground approximately past the collision, sliding down the runway for a further . Upon impact with the runway, the full load of fuel, which had caused the earlier delay, ignited immediately into a fireball that could not be subdued for several hours. One of the 61 survivors of the Pan Am flight 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." Veldhuyzen van Zanten was KLM's chief of flight training and one of their most senior pilots. About two months before the accident, he had conducted the Boeing 747 qualification check on the first officer of Flight 4805. KLM had suggested initially that Veldhuyzen van Zanten should help with the investigation, unaware that he was the captain who had been killed in the accident. ==Victims==