Abstract: A method for operating a gas turbine engine system under baseload and/or a high part load conditions is disclosed, the gas turbine engine system includes a gas turbine engine with at least one compressor with at least one row of adjustable variable vanes for control of the inlet air mass flow; at least one combustor; at least one turbine. A control system is provided, which, on the basis of and as a function of at least one measured temperature value measured upstream of the compressor or a measurable quantity directly functionally related thereto, controls the position of the variable vanes such that at least one measured pressure value varying with the angular position of the variable vanes is at a predefined target pressure which is a function of said first temperature.