Plain English Meaning

How far the pilot can actually see when looking down and ahead toward the runway during an approach. It is the view along the angle of descent, not straight ahead at ground level, so it can be less than what the airport instruments report.

Full Definition

The distance a pilot can see along the angled line of sight from the cockpit on approach down to the runway environment, as opposed to the horizontal visibility measured at ground level. Because the pilot is looking through the atmosphere at an angle, slant visual range is often shorter than the reported runway visual range (RVR) when , , or is present.