An extended Lattice-Boltzmann Method (LBM) for the simulation of transonic flows is proposed for increasing the Mach number range of the regular method while preserving its advantages. Regular methods based on single-layer models are efficient and show low artificial dissipation but are limited to weakly compressible flows, where supersonic flow and shock waves are absent. For transonic applications, methods based on multi-lattice models are better posed and can provide accurate results, but they are considerably more costly and show more artificial dissipation. In that context, the extended single-layer method allows the simulation of compressible flows with local Mach numbers up to 1.2, while preserving efficiency and low dissipation. The extended LBM method of SIMULIA PowerFLOW is described in the present work and is validated against aerospace test cases while being compared to the other methods.