REVEALED: The secret code your pilot will use if your plane has been hijacked

Though plane hijackings are rare, there have been several high profile cases to shock the world over the past few decades. 

One of the most mysterious hijackings was carried out by a man dubbed DB Cooper in 1971, and still remains an unsolved case to this day. 

Pilots are well-trained in every emergency situation they could possibly encounter during a flight. 

Plane hijackings are no different. There is a special code pilots must use to communicate such a scenario to air traffic control back on ground.

The distress code of 7500, sent through an electronic device called a transponder, signals a hijacking or unlawful interference. 

This communication, called squawking, is done silently so that the hijacker remains unaware, thereby creating an advantage for pilots. 

It’s not the only distress code pilots hope they never have to use. 

Squawking 7700 indicates a general emergency, while 7600 signals a loss of radio communication.

There have been several instances of pilots accidentally sending the hijack code to air traffic control. 

Last year a pilot hit the emergency hijack button twice by mistake on a Saudi Airlines flight to the Philippines. 

The error caused the plane to be separated from other flights at Manila International Airport when it touched down. 

Police surrounded the Boeing 777 and passengers were not allowed to disembark for more than two hours.

Earlier this year a Malaysia Airlines flight from Melbourne to Kuala Lumpur was forced to return to Australia when a disruptive passenger tried to enter the cockpit. 

Local reports said 11 passengers tackled a man holding a device after he claimed he had a bomb. 

The plane was forced to land and requested security assistance.

Passengers were kept on board for 90 minutes after the aircraft touched down, as a bomb search was conducted.