Fatal lessons: World's worst midair collisions changed the course of aviation history

Each brought world press coverage of tragedies in the sky that left hundreds dead, mysteries swirling and quantum shifts in aviation safety.

Despite decades of improvements in air traffic control systems and jet safety, midair collisions have remained a recurring, although extremely rare, part of aviation history.

Wednesday's collision between a commercial airplane and an Army helicopter near Ronald Reagan Washington National Airport became the latest in a list of midair disasters that have haunted travelers, investigators and researchers for nearly a century.

"It’s the combination of the rarity as well as the almost immediacy of the tragedy, that’s why it’s so shocking," said University of North Dakota aviation professor Nicholas Wilson.

Several experts told USA TODAY that Thursday's crash, which killed 67, was the worst midair disaster over the United States since the 1980s, although there have been other notable collisions worldwide. The tragedies often galvanize sweeping changes in the industry to ensure nothing similar happens again.

“Our history has been riddled with aviation accidents since the Wright brothers,” said Air Force veteran and Western Michigan University professor Nicholas Rowe, “and each one results in something we can learn.”

Here are some of the worst, what caused them, and what changes happened after the tragedies:

Disaster over LA

The last time America saw a midair disaster comparable to Wednesday’s collision, it was so horrifying that it caused the entire industry to change, according to Wilson, the North Dakota aviation expert.

Aeroméxico Flight 498 collided with a private plane over Los Angeles in 1986. The Piper PA-28 Cherokee clipped the tail of the commercial plane but it spelled disaster for everyone on board the two planes and many on the ground below.

The Cherokee slammed into a ‒ mercifully ‒ empty playground.

Suburbanites living below the path of the Aeroméxico plane weren’t so lucky. Flight 498 plummeted into a residential neighborhood, killing all 64 people on board, 15 people on the ground and injuring many others.

An investigation by the transportation agency laid the blame on the Piper for entering the airspace without required clearance.

The Federal Aviation Administration responded by requiring all commercial aircraft be equipped with a traffic collision avoidance system that monitors the air for other aircraft and warns pilots to either descend or ascend if another plane is nearby.

European disaster in 2002

The traffic collision avoidance systems have become so adept they are often more reliable than actual air traffic controllers. Crews ignoring the system’s directions can lead their passengers into disaster.

That’s exactly what happened with BAL Bashkirian Airlines Flight 2937 when it collided with DHL International Aviation ME Flight 611 near the German-Swiss border in 2002, resulting in the death of all 71 aboard the two planes.

The Bashkirian crew failed to follow the plane’s traffic collision avoidance system, a German Federal Bureau of Aircraft investigation found, leading it to collide with the cargo airline.

German investigators also laid blame on Swiss air traffic control for their management of the airspace.

A distraught Russian man hunted down and killed the controller on duty in the wake of the tragedy that left the Russian man’s family dead. 

The collision led to a redesign of traffic collision avoidance systems to ensure directions were clear to pilots and highlighted the importance of following the traffic collision systems' directives even over conflicting orders from air traffic controllers.

Grand Canyon midair collision

Aviation's first major midair collision happened when the industry was still in its Wild West days. Airspaces went unregulated, controllers left pilots responsible for keeping their distance from other aircraft and tragedy ensued.

The “big one,” as Embry‑Riddle Aeronautical University professor Robert Joslin calls it, happened over the Grand Canyon in 1956 when United Airlines Flight 718 collided with Trans World Airlines Flight 2.

All 128 people on both planes died, making it the first commercial airline collision with over 100 deaths. The two planes were headed from Los Angeles to the Midwest when they collided over Arizona. 

Authorities responded by heightening air traffic control regulations to ensure pilots wouldn’t be left to fend for themselves.

“Sometimes things like this have to happen to get things moving along,” Joslin said. “It’s very unfortunate.”

Deadliest collision happened on the ground

The paramount need for aircraft vigilance even extends to when planes are on the ground.

The worst collision of all time happened on a crowded tarmac on the Spanish island of Tenerife in 1977.

KLM Flight 4805 was taking off when it ran broadside into Pan Am Flight 1736. All 248 people on board the KLM plane died; 335 of the 396 people on the Pan Am plane died. 583 died in total.

The disaster happened amid a crowded day at the airport. Many aircraft had been diverted to Tenerife because of a bomb threat at another nearby destination. Visibility was poor due to fog. 

Spanish authorities concluded the KLM captain mistakenly believed air traffic control signaled the plane to take off.

The disaster highlighted the importance of developing a standardized language for aeronautical communications and instilling exact compliance with air traffic control instructions. 

World’s deadliest midair collision

The world’s deadliest midair collision also happened amid mistaken commands from air traffic control when Kazakhstan Airlines Flight 1907 collided with Saudia Flight 763 over the northern Indian city of Charkhi Dadri in 1996.

All 349 people on board both planes died, making it the deadliest midair collision ever.

Investigators found poor English language skills among the crew led them to misinterpret directions from air traffic control. They also found the crew aboard the Kazakhstan Airlines plane failed to maintain the proper altitude.

India’s aviation agency mandated all aircraft flying in and out of the country have a system to help avoid collisions. The mandates paved the way for traffic collision avoidance systems to be used worldwide.

(This story has been updated to add new information.)