An apparatus and method of operating a gas turbine engine

A gas turbine engine (10) and an apparatus for operating the gas turbine engine (10) comprises at least one microphone (62) to detect the sound of impacts of particles on a surface of the gas turbine engine (10) or a surface of an associated aircraft, a recorder (64) to record the sound of the impacts, an analyser (66) to analyse the sound of the impacts of the particles in terms of frequency, amplitude and time and a store (68) of sounds of impacts, the stored sounds of impacts correspond to unfavourable weather conditions. A comparator (70) compares the sound of the impacts of particles with one or more sounds of impacts stored in the store (68) of sounds of impacts and if the comparator (70) determines that the sound of the impacts of particles matches one or more stored sounds of impacts a signal is sent to a control system (72) for the gas turbine engine (10) to adjust the operation of the gas turbine engine (10) such that it operates in a safe mode of operation.