A Gals (Globally Asynchronous Locally Synchronous) system typically consists of a collection of sequential, deterministic components that execute concurrently and communicate using slow or unreliable channels. This paper proposes a general approach for modelling and verifying Gals systems using a combination of synchronous languages (for the sequential components) and process calculi (for communication channels and asynchronous concurrency). This approach is illustrated with an industrial case-study provided by Airbus: a Tftp/Udp communication protocol between a plane and the ground, which is modelled using the Eclipse/Topcased workbench for model-driven engineering and then analysed formally using the Cadp verification and performance evaluation toolbox.