The application o acoustic emission (AE) to help in a range of structural test situations is described, for a number of composite and metallic aerospace structures. On metallic strikers, its use on the Royal Air Force fleet of 25 VC-10 aircraft during periodic proof pressure testing is described, as well as its use during periodic re-qualification of F-111 airframes during full-scale static test at low temperature. Application to composite and bonded structures include the development and production testing of the SPELDA for ARIANE IV, the structure which supports the rocket payload, and its use during the full-size static testing of the new SAAB Gripen fighter. The paper covers the development of test procedures, technology transfer to operators previously unfamiliar with AE methods, and fundamentally what can be expected from the use of the method in structural test situations.