A flight control system is provided with one or more modal sensors that are each configured to measure the rate and possibly acceleration for a flexible body mode of the flight vehicle. The modal sensor's rate and suitably acceleration are subtracted from the rate and acceleration measured by the IMU such that the values provided to the flight controller more closely represent only the rate and acceleration of the flight vehicle's rigid airframe component. A piezoelectric modal sensor is capable of sensing a particular flexible body mode over variations in the modal frequency without inducing additional phase loss in the control loop in order to maintain suitable phase and gain margins. Sensors are suitably provided for at least and possibly only the 1.sup.st lateral bending modes in the pitch and yaw channels.