AT-3

AT-3 may be:

* AT-3 (jet trainer) of the Republic of China Air Force (Taiwan)
* AT-3 plane, Very Light Aircraft
* AT-3 Sagger, Soviet anti-tank missile
* AT-3 (MATH-MATIC) compiler for UNIVAC mainframe computers
* .at3, extension for audio files compressed with Sony's ATRAC3 algorithm