Despite the high level of automation, the practicability of formal veri cation through model-checking of large models is hindered by the combinatorial explosion problem. In this paper we apply a novel context-aware veri cation technique to the Landing Gear System (LGS). The idea is to express and verify requirements relative to certain environ- mental situations. The system environment is decomposed into several independent scenarios (contexts), which are successively composed with the system during reachability analysis. These contexts are speci ed us- ing a language called CDL (Context Description Language), based on activity and message sequence diagrams. The properties to be veri ed are speci ed with observer automata and attached to speci c regions in the context. This approach enables an automated context-guided de- composition of the veri cation into smaller problems, hence e ectively reducing the state-space explosion problem. In the case of the LGS this technique enabled the fully-automated decomposition of the veri cation into 885 smaller model-checking problems.