A gas turbine, computer software and a method for controlling an operating point of the gas turbine that includes a compressor, a combustor and at least a turbine is provided. The method comprises: determining an exhaust pressure at an exhaust of the turbine; measuring a compressor pressure discharge at the compressor; determining a turbine pressure ratio based on the exhaust pressure and the compressor pressure discharge; calculating a primary to lean-lean mode transfer threshold reference curve as a function of the turbine pressure ratio, where the primary to lean-lean mode transfer threshold curve includes points at which an operation of the gas turbine is changed between a primary mode to a lean-lean mode; and controlling the gas turbine to change between the primary mode and the lean-lean mode.