Skyjacking, or aircraft hijacking, refers to an unlawful seizure of an aircraft by an individual or a group. In most cases, the hijackers use the passengers as hostages, asking for monetary ransoms or for some political concession from the government. The pilot is forced to follow the hijackers' orders to fly to a specific place.

In the history of air transportation, there have been quite a few hijackings. Compared to a deadly breakdown in the air, hijackings seem less dangerous. However, Can you imagine being on a plane that has been hijacked? Even if you are lucky enough to survive, it is always a terrifying experience.

The following are the top 10 most terrifying skyjackings in the world. (Listed in chronological order)

September 11 attacks, 2001

September 11 attacks, 2001 [File photo]

The September 11 attacks were a series of four terrorist hijacking attacks launched by the Islamic terrorist group al-Qaeda upon the United States on Sept. 11, 2001. A total of 19 al-Qaeda terrorists hijacked four passenger airliners for suicide attacks.

Two of the planes, American Airlines Flight 11 and United Airlines Flight 175, were flown into the North and South towers of the World Trade Center complex in New York. American Airlines Flight 77 was flown into the Pentagon, the headquarters of the US Department of Defense. The fourth plane, United Airlines Flight 93, failed to hit a target in Washington, D.C., and instead, it crashed into a field near Shanksville, Pennsylvania, as its crew members and passengers tried to stop the hijackers.

The attacks killed 3,201, and 6,291 were injured.