The Worst Air Disaster in Aviation History

I had just finished watching the 3rd episode of the 16th season of Mayday/Air Crash Investigation. I can’t believe that the show has been running for sixteen seasons already! Time flies so fast. I can still remember back in my early days in college when I would stay up late just to binge watch this on YouTube. Did I mention that our DSL connection that time wasn’t really that fast? So it was really a struggle to catch up with the latest episodes and seasons of this show. For some, watching ACI is scary especially when you’re a frequent flyer but for me, it really is an informative show and I learned a LOT of things which eventually helped me in building my career in air traffic control.

The third episode of the latest season of Mayday/Air Crash Investigation is all about the infamous Tenerife accident, the deadliest accident in aviation history. Shortly after 5PM, two Boeing 747s -- Pan Am and KLM Royal Dutch Airline -- collided on the runway. 583 lives were lost in an instant. This is a summary of what really transpired on that fateful day.

• On March 27, 1977, a bomb went off at Gran Canaria Airport, the main gateway of Canary Islands, forcing numerous arriving flights to divert at Tenerife Airport roughly 25 minutes away from Gran Canaria.

• Tenerife Airport has a single runway and a parallel taxiway that are both long enough to accommodate wide-bodies such as the Boeing 747 but that’s it. The ramp and terminal weren’t that big. Some planes were forced to park right at the taxiway. There were only two air traffic controllers on duty that time and they were surprised by the volume of air traffic. But, they somehow managed it professionally.

• Hours later, Gran Canaria Airport reopens and Tenerife Tower allowed all aircraft to start their engines at their own discretion. Pan Am was ready for start-up but can’t move because the KLM is blocking their way because it was still on its refueling process. They were 12-meters short of the wingtip clearance. They had no choice but to wait for the KLM to finish its business.

• Tenerife’s geography is unique. It is surrounded by towering mountains and sea. Fog coming from the mountains started to roll on the runway which quickly deteriorated the visibility.

• After refueling, the KLM 747 was instructed by Tenerife Tower to taxi to the active runway. Meanwhile, Pan Am 747 was also instructed to follow their leading traffic on the active runway.

• KLM was instructed by the Tenerife Tower to make a 180-degree turn at the end of the runway in preparation for its departure. Meanwhile, the Pan Am was instructed to vacate at the third taxiway (Charlie 3), but they missed it due to poor visibility. More so, the third exit requires them to make a very tight turn (148 degrees to be exact). Gargantuan aircraft such as the Boeing 747 weren’t designed to execute that maneuver. Along the way, the pilots were having a hard time to understand the air traffic controllers because their native language is Spanish. They were talking in English but with a thick accent.

• Pan Am decided to exit at the Charlie 4 taxiway since they only need to make a 45 degree turn, ideal for the aircraft. After the air traffic controller gave KLM the ATC clearance (the route of flight to their destination plus some information in their standard information departure), the KLM pilot mistakenly took it as a take-off clearance and was rolling for departure.

• The flight crew of the Pan Am 747 saw the inevitable and they tried their best to expedite their exit at Charlie 4, but it was too late. Sixty-one (61) passengers and crew of Pan Am survived the ordeal. All passengers and crew of the KLM died.

As the Pan Am 747, known as "Clipper 1736," was making its way in a "back taxi" on Runway 30, its crew was instructed to turn off at Exit C3. Visibility was bad, however, and the Pan Am crew missed the exit. 

Investigators from the Netherlands, United States of America, and Spain went to the ground zero. They recovered the black boxes and VCRs of both aircaft, and they interviewed the air traffic controllers on duty during the time of the incident. Here are the vital things that they found out after the investigation:

• Captain Jacob Van Zanten got pressured by the company rules. If they exceed on the hours of their duty, they will be forced to cancel the flight. It’s a logistical nightmare since Tenerife is not their destination airport. More so, their licenses will be revoked.

• Captain Van Zanten is a star pilot of KLM and a flight instructor. His judgment was affected because he got used to flight simulators. In flight simulators, there’s no air traffic control. He was preoccupied that after hearing the ATC clearance of ‘after take-off, turn right heading 110, and report when ready’, he thought that he was being cleared for take-off by the Tower controller.

Because of this incident, lots of revisions in company training and standard work hours, and air traffic control procedures were made. As one of the training officers in my facility, I would always remind my colleagues that they should stick with the standard procedures. The standard procedures were created in the first place to ensure the safe, orderly, and expeditious flow of air traffic. Although we cannot really avoid some circumstances wherein we need to deviate from what was written in the book, we have to see to it that we still meet the safety requirements mandated by the International Civil Aviation Organization (ICAO). One small mistake in strip markings or in phraseology for instance would lead to disasters like this one. The accident wasn’t solely blamed to Captain Van Zanten. There were lots of factors to consider prior the accident. 

Today, when the tower is not equipped with ground radar, no two aircraft shall enter the active runway especially when the RVR (runway visual range) is less than 800 meters. Also, there were changes in the phraseology: you can’t say ‘after take-off’ or any other equivalent phraseologies for that matter. It should be ‘after departure’. You can only use the ‘take-off’ phrase when giving take-off clearances.

The last but not the least, do not do anything unless the air traffic controller told you to do so.