An aircraft detection system for an aircraft having an auto pitch trim function, comprising: a source of elevator load data , the elevator load data representative of sensed load on an elevator flight control surface; a source of aircraft speed data , the aircraft speed data representative of sensed aircraft speed; a source of pitch trim position data , the pitch trim position data representative of actual aircraft pitch trim position; a source of engine thrust data , the engine thrust data representative of sensed engine thrust; a source of inertial data , the inertial data representative of sensed aircraft bank angle; and a processing system coupled to receive the elevator load data, the aircraft speed data, the position trim data, the engine thrust data, the inertial data and initial condition center-of-gravity (CG) data, the initial condition CG data representative of at least an estimated initial position of the CG of the aircraft, the processing system configured to process at least the aircraft speed data, the position trim data, the engine thrust data, the inertial data and the initial condition CG data to: (i) determine an expected elevator load on the elevator flight control surface, (ii) determine if the expected elevator load exceeds the sensed elevator load by a predetermined magnitude, and (iii) when the expected elevator load exceeds the sensed elevator load by a predetermined magnitude, generate a disconnect signal that will disable the auto pitch trim function. a source of elevator load data , the elevator load data representative of sensed load on an elevator flight control surface; a source of aircraft speed data , the aircraft speed data representative of sensed aircraft speed; a source of pitch trim position data , the pitch trim position data representative of actual aircraft pitch trim position; a source of engine thrust data , the engine thrust data representative of sensed engine thrust; a source of inertial data , the inertial data representative of sensed aircraft bank angle; and a processing system coupled to receive the elevator load data, the aircraft speed data, the position trim data, the engine thrust data, the inertial data and initial condition center-of-gravity (CG) data, the initial condition CG data representative of at least an estimated initial position of the CG of the aircraft, the processing system configured to process at least the aircraft speed data, the position trim data, the engine thrust data, the inertial data and the initial condition CG data to: (i) determine an expected elevator load on the elevator flight control surface, (ii) determine if the expected elevator load exceeds the sensed elevator load by a predetermined magnitude, and (iii) when the expected elevator load exceeds the sensed elevator load by a predetermined magnitude, generate a disconnect signal that will disable the auto pitch trim function. (i) determine an expected elevator load on the elevator flight control surface, (ii) determine if the expected elevator load exceeds the sensed elevator load by a predetermined magnitude, and (iii) when the expected elevator load exceeds the sensed elevator load by a predetermined magnitude, generate a disconnect signal that will disable the auto pitch trim function. <EOS>