Controller and method

A method of controlling a gas turbine arranged to supply a load L, the gas turbine comprising a compressor arranged to operate at a rotational speed n, a combustor and a fuel supply means comprising a first fuel supply means and a second fuel supply means, wherein the compressor is arranged to provide air to the combustor at a steady state air mass flow rate {dot over (m)}SS and wherein the fuel supply means is arranged to supply fuel at a fuel mass flow rate mtotal to the combustor, the method comprising:

• responsive to a load change ÄL to the load L, controlling the compressor to provide air to the combustor at a new air mass flow rate {dot over (m)}TR,
• wherein the new air mass flow rate {dot over (m)}TR is within a range between a first threshold {dot over (m)}LBO and a second threshold {dot over (m)}SUR.