runway and terrain slopes illusion

runway and terrain slopes illusion

Three different perspectives of the runway depending on the slope.An illusion caused by an up-sloping runway, up-sloping terrain, or both during an approach for landing. The pilot perceives that the aircraft is at a higher altitude than it actually is and thus tends to fly a lower approach. A down-sloping runway, down-sloping approach terrain, or both can have the opposite effect.
The pilot should be aware of the likely effects of these slopes and take the help of an approach such as a VASI (visual approach slope indicator) where these are available.