This book offers an HPSG-based discourse grammar for a controlled language (Air Traffic Control) that allows the identification of well-formed discourse patterns. A formalisation of discourse theoretical structures that occur especially in crisis situations that involve potential aviation disasters is introduced. Of particular importance in this context are discourse sequences that help secure uptake among the crew and between crew and tower in order to coordinate actions that might result in avoiding a potential disaster. In order to describe the relevant phenomena, an extended HPSG formalism is used. The extension concerns the capability of modelling speech acts as proposed by Searle & Vanderveken (1985). The grammar is modelled by employing XML as a denotational semantics and is applied to the corpus data. This work thus lays the foundation for the automatic recognition of discourse structures in aviation communication.