This article aims to define ergonomic linguistics as a field of linguistics that draws on the experience of ergonomics which aims at meeting specific needs, all the while benefitting from scientific linguistic knowhow. The concept of usability, central in ergonomics as it puts people at the heart of needs, is adapted to the perspective of ergonomic linguistics. In order to put this branch of linguistics to work, we need to take into consideration on the one hand the real life corpora or language use in context, and on the other hand implement tests to evaluate their proper usage and relevance. We base our study on controlled languages because of the way they are constituted (the rules that make them) and the way they are evaluated (or lack thereof). Three studies in the fields of aeronautics and space are presented here to show how we use the concept of ergonomic usability in order to evaluate and propose linguistic recommendations for controlled languages. By commenting on these studies we show how ergonomic linguistics is implemented.