In mathematics, the chord of a circle is a segment that connects two points on a circle. A chord that passes through the centre of the circle measures its diameter. On an airplane, the chord also measures a distance between two points at a specific location on the aircraft. When it varies, as is the case on some ‘planes, an average, called the "mean aerodynamic chord", is calculated.

But what exactly does the chord on a ‘plane measure? Look for the answer at the end of the video, in which we let several passengers express their opinion.