When cleared to land, which visual cue indicates that you are off course?

The correct indication of being off course when cleared to land is represented by the red lights on the runway. In the context of visual cues used during the landing phase, the approach lighting system typically collaborates with the runway lights to provide pilots with critical situational awareness about their alignment with the runway centerline.

When you are on the correct glide path and aligned with the runway, the lights along the center of the runway provide white lights. If you start to deviate off the centerline, typically, the lights will change in color, often to red on one side, indicating that you are too far from the desired approach path. Hence, the presence of red lights is a clear indicator that corrective action is needed to regain the proper alignment with the runway.

The presence of white lights alone indicates being on the right path, while red lights signal an impending need for course correction. Therefore, red lights on the runway are the key visual cue that signals you are not on the right approach.