The first production use of practical acoustic emission (AE) on aircraft was on the F-111, where more than 240 U.S. and Australian aircraft have been successfully monitored during cold proof testing since 1987. A key factor was the design of an instrument which automatically configured itself at power-on, so that aircraft testing could take place in a highly efficient and reliable manner. The second production use of AE on aircraft was on the VC-10, where an entire fleet of 22 aircraft was monitored 40 times during pneumatic proof pressurization. The monitoring of this large transport required anywhere from 282 to 313 narrowband AE sensors per aircraft. In both aircraft types, numerous significant defects were discovered through AE-based nondestructive testing. Finally, we present on-going in-flight AE research. This new research uses digital waveform processing of wideband AE signals and offers the potential of adding new and complementary capabilities to classical, narrowband AE.