Plane crashes are rare, and air transport is not only the fastest but also the one with the least recorded accidents. However, there are a few plane crashes that have happened. The main causes of these crashes were either human error or the result of natural disasters. However, these accidents have helped aviation bodies around the world come up with solutions that can help prevent other similar accidents. According to the Telegraph, there was an air disaster that was averted on July this year when an Air Canada plane was about to land on a busy taxiway where four planes were waiting.

Here are some of the world’s worst aviation disasters.

1. The 9/11 terrorist attack

The 9/11 was The Worst aggression ever done to the American people outside of a war. According to Metro, on the morning of Tuesday, September 11, 2001, two planes were hijacked by terrorists and crashed into the WTC towers, while a third one was hijacked and flown into the Pentagon. The fourth plane which was meant to hit the White House or the Capitol, crashed in Pennsylvania after the passengers fought the hijackers. In total, 2,996 people died, and over 6000 were left injured that day Among the dead were all the passengers on the four planes, 2,606 people in and around the WTC, and 125 from the Department of Defense.

The planes involved were American Airlines Flight 11 and Flight 77, and United Airlines Flight 175 and Flight 93.

2. Malaysia Airlines 370

According to Popular Mechanics, there was no May Day call or sign of distress from the Malaysian jet when it dropped off the radar on March 8, 2014. The airline, a Boeing 777 had 239 passengers on board and had left Beijing for Kuala Lumpur.

It is the biggest mystery in aviation’s history. The jet was said to have changed direction and headed south, and it is believed that it flew for seven hours before running out of fuel and plunging into the Indian Ocean. Reports indicate that the accident might have been caused by either passenger or crew sabotage, or hypoxia.

3. Malaysia Airlines Flight 17

According to the Telegraph, the Boeing 777-200 was shot down near the Russian border in the east of Ukraine. It was suspected that pro-Russian forces were responsible for the act. At the time, there was a war in Donbass between insurgents and the Ukranian government. The plane was destined for Kuala Lumpur from Amsterdam, and all the 298 people on board perished. The debris of the plane was found in a field near Torez. Since then, airplanes have been advised to avoid the Ukranian airspace.

4. Air France 447

After just three hours in the air from Rio to Paris, the Airbus A330-200 met a thunderstorm, and nobody heard of it again, according to Popular Mechanics. It was reported that the aircraft fell from an altitude of 38,000 feet and plunged into the Atlantic Ocean.

None of the 228 people on board survived. Some wreckage pieces were spotted on the surface of the water a few days later. Two years after the accident, the bodies of the victims and the black box were retrieved. It was discovered that the accident was caused by the pilot’s failure to take correct action during the thunderstorm.