ATR may stand for:

Aviation[link]

• Aircraft Type rating, an addition to a pilot's license which allows the pilot to serve as pilot-in-command of a particular aircraft type in commercial operations
• ATR (aircraft manufacturer) an Italian-French aircraft manufacturer
  • ATR 42 twin-turboprop, short-haul regional airliner, 40-50 passengers, maiden flight 1984, over 400 delivered
  • ATR 72 twin-turboprop, short-haul regional airliner, seats up to 74, maiden flight 1988, over 400 delivered

Military[link]

• Anti-tank rifle
• Army Training Regiment in the British Army

Music[link]

• All That Remains, a metalcore band from Massachusetts, United States
• Atari Teenage Riot, a German techno band performing "digital hardcore" music
• ATR (Atari Teenage Riot song)

Science and technology[link]

• Advanced Telecommunications Research Institute International
• Advanced Test Reactor, a research reactor at the Idaho National Laboratory
• Against-the-rule astigmatism, a form of refractive error
• Answer to reset, a message output by a contact Smart Card
• Ataxia telangiectasia and Rad3 related, a protein involved in DNA damage repair
• Attenuated total reflectance, a sampling technique used to enable infrared spectroscopy to be carried out directly on samples in the solid state
• Automatic target recognition, the ability of an algorithm to recognize targets based on data obtained from sensors
• Autothermal reforming, a natural gas reforming technology

Other uses[link]

• Absent Teacher Reserve, tenured teachers from closed schools, New York City
• Advanced tongue root, a phonological feature in Linguistics.
• Americans for Tax Reform, an American anti-tax advocacy group
• Art therapist registered (ATR), denotation for a registered Art Therapist with licensure
• Atmore (Amtrak station), Amtrak station code ATR
• ATR.1 certificate, a customs document used in trade between EU members and Turkey.
• Average True Range, a market volatility indicator

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