The aim of this study is to establish the co-operative communication strategies that are used in air traffic control (ATC) conversations. The research deals with the question: what kind of co-operative communication strategies do pilots and controllers employ in a speech situation with a restricted use of vocabulary, which generally does not permit any deviations from standard phraseology? The strategies in ATC speech are then compared to those used by second language learners. Faerch and Kasper's (1983) taxonomy of communication strategies will serve as a basis for this comparison. The author analyses authentic speech samples from various ATC workstations at Zurich Airport and evaluates various aspects of phraseology training of air traffic controllers.