In addition there were concerns over maintaining precise control at supersonic speeds. Both of these issues were resolved by active ratio changes between the inboard and outboard elevons, varying at differing speeds including supersonic. Only the innermost elevons, which are attached to the stiffest area of the wings, were active at high speed.[120] Additionally, the narrow fuselage meant that the aircraft flexed.[1] This was visible from the rear passengers' viewpoints.[121]