VFR · Lesson 75 · 8 min · ACS PA.XI

Night Illusions and Airport Lighting

Summary

Beware the black hole, autokinesis, and false horizons; read the beacon, runway, and threshold lights and the VASI/PAPI; and key the mic 7/5/3 to control the lights where they are pilot-activated.

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Night visual illusions · Topic mastery: Not started

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The black-hole approach illusion most typically causes a pilot to do what?

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Why this matters in flight

Night illusions have flown healthy pilots into the ground on perfectly good approaches. Reading airport lighting correctly — and knowing how to turn it on yourself — keeps a night arrival stabilized and safe.

Figure 17-22. A false horizon at night, where scattered ground lights blend with the stars and mislead the eye.
Figure 17-22. A false horizon at night, where scattered ground lights blend with the stars and mislead the eye.Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25C) · public domain
Figure 14-29. A VASI, where red-over-white bars indicate the correct on-glidepath approach.
Figure 14-29. A VASI, where red-over-white bars indicate the correct on-glidepath approach.Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25C) · public domain

Darkness removes the visual references your brain relies on, and it invents a few false ones. The black-hole approach happens over dark, featureless terrain or water: with nothing to judge height against, pilots tend to fly dangerously low, so a visual glideslope aid becomes critical. Autokinesis makes a single steady light seem to drift if you stare at it, and a false horizon from sloping clouds or blended ground lights and stars can tempt you to bank toward the wrong reference. Airport lighting is your antidote. A rotating beacon flashing white and green marks a lighted land airport; runway edge lights are white, taxiway edge lights are blue, and green/red lights mark the thresholds. A visual glideslope aid shows your descent path: on a two-bar VASI, red over white means on the glidepath; on a four-light PAPI, two white and two red means on the glidepath. At many untowered fields the lights are pilot-controlled: key the mic 7 times for high, 5 for medium, and 3 for low intensity on the published frequency.

Key terms

Black-hole approach
A too-low approach over dark, featureless terrain with no height cues.
Autokinesis
The illusion that a fixed light is moving when stared at.
Pilot-controlled lighting
Runway lights activated by keying the microphone on a set frequency.

Sources & references · 3 · 4 linked

Every claim traces to a source — paraphrased knowledge elements pointing at the governing FAA publication. Items marked verified have been checked against the retrieved source text; the rest are pending verification. Where the exact page or regulation has been located in a retrieved document, the source links straight to it.

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