Sky marshal
（重定向自Sky Marshals）
A sky marshal (also known as air marshal, flight marshal, or FAM) is an undercover law enforcement or counter terrorist agent 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 Austrian Einsatzkommando Cobra, Royal Canadian Mounted Police, German Federal Police, National Security Guard in India, Metropolitan Police SO18 (Aviation Security Operational Command Unit) or US Federal Air Marshal Service.