Abstract: An accurate and compact flap skew detection system that operates independent of the flap-drive system comprises, in a preferred embodiment, three major elements; a rotary position sensor located on fixed wing structure; a push-pull link and crank arm to convert translational flap motion into rotary sensed motion at the sensor; and a computer processing means to process the rotational sensed information and to compute a flap skew algorithm. Inter-flap and intra- flap translational motion is sensed and compared using a plurality of rotary sensors. Sensors falling outside of predetermined limits or violating control law rules indicate a non-synchronous or asymmetrical “skewed” condition.