A method of operating a gas engine , which uses main gaseous fuel and pilot liquid fuel for igniting the main gaseous fuel, wherein combustion of the lean air-fuel mixture is ignited by injecting a small amount of liquid pilot fuel and igniting the pilot fuel in diesel process, the method comprising steps of: - measuring charge air pressure of the engine, - generating a base timing instruction and a base duration instruction for pilot liquid fuel introduction based on said one or more signals indicative to the engine's operation condition, - introducing main gaseous fuel into a combustion chamber of the engine via an intake channel of the engine, - acquiring a transient load status based on said one or more signals indicative to the engine's operation condition, - in an event of the transient load status is non-confirmative, igniting the main fuel in the combustion chamber by introducing pilot fuel into the combustion chamber of the engine using the base timing and the base duration instructions, - and in an event of the transient load status is confirmative, • the base timing instruction is corrected with a timing compensation value acquired as a function of the measured charge air pressure and difference between the measured charge air pressure and a predetermined reference pressure value, resulting in a corrected timing instruction and the base duration instruction is corrected with a duration compensation value based on, or as a function of a difference between the measured charge air pressure and a predetermined reference pressure value, resulting in a corrected duration instruction, and - igniting the main gaseous fuel introduced via the intake channel of the engine in the combustion chamber by introducing pilot liquid fuel into the combustion chamber of the engine using the corrected timing and duration instructions. - measuring charge air pressure of the engine, - generating a base timing instruction and a base duration instruction for pilot liquid fuel introduction based on said one or more signals indicative to the engine's operation condition, - introducing main gaseous fuel into a combustion chamber of the engine via an intake channel of the engine, - acquiring a transient load status based on said one or more signals indicative to the engine's operation condition, - in an event of the transient load status is non-confirmative, igniting the main fuel in the combustion chamber by introducing pilot fuel into the combustion chamber of the engine using the base timing and the base duration instructions, - and in an event of the transient load status is confirmative, • the base timing instruction is corrected with a timing compensation value acquired as a function of the measured charge air pressure and difference between the measured charge air pressure and a predetermined reference pressure value, resulting in a corrected timing instruction and the base duration instruction is corrected with a duration compensation value based on, or as a function of a difference between the measured charge air pressure and a predetermined reference pressure value, resulting in a corrected duration instruction, and • the base timing instruction is corrected with a timing compensation value acquired as a function of the measured charge air pressure and difference between the measured charge air pressure and a predetermined reference pressure value, resulting in a corrected timing instruction and the base duration instruction is corrected with a duration compensation value based on, or as a function of a difference between the measured charge air pressure and a predetermined reference pressure value, resulting in a corrected duration instruction, and - igniting the main gaseous fuel introduced via the intake channel of the engine in the combustion chamber by introducing pilot liquid fuel into the combustion chamber of the engine using the corrected timing and duration instructions. <EOS>