An unmanned aerial vehicle (UAV), commonly known as a drone, as an unmanned aircraft system (UAS), and also referred by several other names, is an aircraft without a human pilot aboard. The flight of UAVs may be controlled with various kinds of autonomy : either by a given degree of remote control from an operator, located on the ground or in another vehicle, or fully autonomously, by onboard computers.[1] Historically, UAVs were simple remotely piloted aircraft, but autonomous control is increasingly being employed : UAV stands nowadays at the crossroads of aviation, electromagnetics, radiocommunication, computer science, avionics, automation, cybernetics, and even core fields of artificial intelligence such as computer vision, decision-making, machine learning and robotics. UAVs are often preferred for missions that are too "dull, dirty or dangerous"[2] for manned aircraft. They have and are mostly found in military and special operation applications. Though, UAVs are increasingly finding uses in civil applications,[3] such as policing and surveillance, aerial filming and hobbyist First Person Video drone racing. There are several names in use for unmanned aerial vehicles, which generally refer to the same concept. The term drone, more widely used by the public, was coined in reference to the resemblance of dumb-looking navigation and loud-and-regular motor sounds of old military unmanned aircraft to the male bee. The term has seen strong opposition from aviation professionals and government regulators.[4] The term unmanned aircraft system (UAS) was adopted by the United States Department of Defense (DoD) and the United States Federal Aviation Administration in 2005 according to their Unmanned Aircraft System Roadmap 2005–2030.[5] The International Civil Aviation Organization and the British Civil Aviation Authority have also adopted the term, while the European Union’s Single-European-Sky (SES) Air-Traffic-Management (ATM) Research (SESAR Joint Undertaking) roadmap for 2020 mentions it too.[6] Unmanned aircraft system emphasizes the importance of other elements beyond an aircraft itself. It includes elements such as the ground control stations, data links and other related support equipment. A similar term is an unmanned-aircraft vehicle system (UAVS) remotely piloted aerial vehicle (RPAV), remotely piloted aircraft system (RPAS). Many similar terms are in use as well. To distinguish UAVs from missiles, a UAV is defined as a "powered, aerial vehicle that does not carry a human operator, uses aerodynamic forces to provide vehicle lift, can fly autonomously or be piloted remotely, can be expendable or recoverable, and can carry a lethal or nonlethal payload".[7] Therefore, cruise missiles are not considered UAVs because, like many other guided missiles, the vehicle itself is a weapon that is not reused, though it is also unmanned and in some cases remotely guided. The definition of UAVs with respect to smaller remote controlled model aircraft is unclear[citation needed]. According to various definitions UAVs may or may not include model aircraft.[citation needed] Some jurisdictions base this definition on size or weight, however, the US Federal Aviation Administration defines any unmanned flying craft as a UAV regardless of size. In another approach, a radio-controlled aircraft becomes a drone with the addition of an autopilot AI, and ceases to be a drone when the AI is removed.[8]