A sky marshal (also known as air marshal or flight marshal) is an undercover law enforcement or security officer on board a commercial aircraft to counter aircraft hijackings. Sky marshals may be provided by airlines such as El Al (who provide sky marshals on every flight), or by government agencies such as the US Federal Air Marshal Service or the German Federal Police. Ocean-going cruise ships have similar officers, known as sea marshals.
The US Federal Aviation Administration began its "Sky Marshal" program in 1968, which eventually became the Federal Air Marshal Service in 1985. That year, an Egyptian security officer on board EgyptAir Flight 648 opened fire on three Abu Nidal Organization hijackers, killing one before being fatally shot himself.
Sky marshals became an issue after the September 11 attacks on the United States in 2001, after which airline security was significantly tightened across the world. In late 2003, the United States ordered foreign airlines to have armed guards on flights to and from the country as a precaution against terrorist attacks. Many of the involved countries and carriers have expressed great reservation towards the idea since they fear that having weapons on board only increases the risk of terrorist actions. Others maintain that these reservations are unfounded, citing the record of El Al, which has a number of armed marshals on each flight, and has only been the victim of one successful hijacking, in 1968 (before sky marshals were routinely on all El Al flights).
In the Film Harold & Kumar Escape from Guantanamo Bay air marshals tackle Harold and Kumar to the ground after the passengers believe a bong is a bomb due to all of the smoke after it has been smashed on to the ground and passengers wrongly assume that it is poison gas.