A gas turbine engine system comprising: a gas turbine engine comprising at least one combustor configured to receive a flow of fuel from a flow control device; and a fuel control system comprising: a piping system configured to channel the flow of fuel from a fuel source to the flow control device; a sensor configured to generate a signal indicative of a property of the flow of fuel wherein the property of the flow of fuel is variable over time; and a controller comprising a processor programmed to: receive the generated signal; characterised in that the processor is further programmed to: use a flow model of the piping system and the received signal, iteratively track the progress of a plurality of discrete volumes flowing through the piping system, wherein said flow model comprises a one-dimensional linear control volume divided into a plurality of control volume elements, the number of control volume elements defining the flow model mesh; and control the flow of fuel using the flow control devices. a gas turbine engine comprising at least one combustor configured to receive a flow of fuel from a flow control device; and a fuel control system comprising: a piping system configured to channel the flow of fuel from a fuel source to the flow control device; a sensor configured to generate a signal indicative of a property of the flow of fuel wherein the property of the flow of fuel is variable over time; and a controller comprising a processor programmed to: receive the generated signal; characterised in that the processor is further programmed to: use a flow model of the piping system and the received signal, iteratively track the progress of a plurality of discrete volumes flowing through the piping system, wherein said flow model comprises a one-dimensional linear control volume divided into a plurality of control volume elements, the number of control volume elements defining the flow model mesh; and control the flow of fuel using the flow control devices. a piping system configured to channel the flow of fuel from a fuel source to the flow control device; a sensor configured to generate a signal indicative of a property of the flow of fuel wherein the property of the flow of fuel is variable over time; and a controller comprising a processor programmed to: receive the generated signal; characterised in that the processor is further programmed to: use a flow model of the piping system and the received signal, iteratively track the progress of a plurality of discrete volumes flowing through the piping system, wherein said flow model comprises a one-dimensional linear control volume divided into a plurality of control volume elements, the number of control volume elements defining the flow model mesh; and control the flow of fuel using the flow control devices. receive the generated signal; characterised in that the processor is further programmed to: use a flow model of the piping system and the received signal, iteratively track the progress of a plurality of discrete volumes flowing through the piping system, wherein said flow model comprises a one-dimensional linear control volume divided into a plurality of control volume elements, the number of control volume elements defining the flow model mesh; and control the flow of fuel using the flow control devices.