Definition
A visual environment encountered when approaching an airport at high elevation in clear, bright weather, where the unusually transparent air and lack of intervening haze cause the pilot to perceive the runway and surrounding terrain as closer than they actually are. This is one of several visual conditions known to produce a landing illusion, in this case the illusion of being too high on approach.
Plain English
When the air is very clear and the airport sits at a high elevation, things look closer than they really are. The runway can seem nearer than it is, which can fool a pilot into thinking they are too high and need to descend more steeply.
Context Anchor
Encountered in optical illusion discussions for visual approaches and landings, especially at airports located well above sea level.
Why Pilots Care
Leads pilots to fly a high or low approach, increasing the risk of landing short or long on the runway.
Grounding Statement
On a very clear day at a high airport, the runway can look so sharp and near that your eyes may overtrust what they see.
Intuition Check
Clear and bright does not always mean easier to judge correctly. In this context, clear bright conditions can remove haze and distance cues that normally help the pilot judge where the aircraft really is.
Example Sentence 1
Briefing the approach into Leadville, the instructor warned that the clear bright conditions of a high altitude airport can make the runway look closer, tempting a pilot to descend too early.
Example Sentence 2
In clear bright conditions of a high altitude airport, the absence of haze made the runway appear farther away, prompting a go-around.