To logically determine data such as engine inlet condition data {a Mach number Mn, pressure height ALT, and outside air temperature (all temperature TAT, true ambient temperature SAT)}, needed based on the other sensor output with an expensive engine inlet sensor removed, in a control device for an aircraft gas turbine engine.

The pressure height ALT is calculated from detected atmospheric pressure P0 (S10), air inflow temperature T1 is assumed as an adequante value supposing the all temperature TAT and the temperature T1 as equal (S12). The Mach number Mn is estimated from the assumed temperature T1 and so on (S14), inflow air pressure P1 is calculated from the Mach number Mn and so on (S16), the temperature T1 is estimated from the pressure P1 and so on (S18): and when the estimated temperature T1 is converged to the assumed temperature T1 (S20), a true ambient temperature SAT is calculated from the temperature T1 and so on (S22). Moreover failure is judged by comparing a calculated value with airframe-mounted computer (ADC) data (S24-S28).