Night Operations
PHAK Ch 17 • Vision, Lighting, Illusions, Currency
Key Takeaways
- Full dark adaptation takes 30+ minutes; one bright flash can reset it.
- Rods (peripheral) are most sensitive in low light — use off-center viewing 10-15° away.
- Hypoxia affects night vision above 5,000 ft — consider supplemental O2 earlier.
- Smoking, carbon monoxide, fatigue, and Vitamin A deficiency all degrade night vision.
Night Vision Physiology
Dark Adaptation
- Takes 30+ minutes for full night vision adaptation
- Rods (peripheral vision) are most sensitive in low light
- Cones (central vision) require more light - use off-center viewing
- Avoid bright lights during adaptation - use red cockpit lighting
- One bright flash can reset adaptation process
Scanning Techniques
- Off-Center Viewing: Look 10-15° away from object to use rods
- Scan slowly - rapid eye movement reduces night vision effectiveness
- Use peripheral vision to detect movement and lights
- Focus on instruments more frequently than day flight
- Avoid fixating on single light source
Factors Affecting Night Vision
- Hypoxia: Vision affected above 5,000 ft at night - consider O2 earlier
- Carbon Monoxide: Even small amounts impair night vision
- Smoking: Significantly reduces night vision (equivalent to 5,000-8,000 ft)
- Fatigue: Decreases visual acuity and adaptation speed
- Vitamin A deficiency: Impairs rod function
- Bright sunlight exposure: Can delay dark adaptation
Key Takeaways
- A white-green rotating beacon = civilian land airport; a daytime beacon means weather below VFR minimums.
- VASI/PAPI on glide path = "red over white, you're alright"; red over red, you're dead.
- PCL: 7 clicks in 5 sec = highest intensity, 5 = medium, 3 = lowest, on the CTAF frequency.
- Runway edge lights are white (amber the last 2,000 ft); taxiway edge lights are blue, centerline green.
Airport Beacons
| Beacon Color | Meaning |
|---|---|
| White-Green | Civilian land airport |
| White-Yellow | Water airport (seaplane base) |
| Green-Yellow-White | Heliport |
| White-White-Green | Military airport |
| Beacon ON during day | Weather below VFR minimums (Class B/C/D) |
Visual Glideslope Indicators
VASI (2-bar)
- Red over Red = too low, Red over White = on glide path, White over White = too high
PAPI
- 4 lights: 4 white = high, 3W/1R = slightly high, 2W/2R = on path, 1W/3R = slightly low, 4 red = low
Tri-Color VASI
- Amber = high, Green = on path, Red = low
Memory Aid
- "Red over White, you're alright. Red over Red, you're dead."
Pilot-Controlled Lighting (PCL)
| Clicks | Result |
|---|---|
| 7 clicks in 5 sec | Highest intensity |
| 5 clicks in 5 sec | Medium intensity |
| 3 clicks in 5 sec | Lowest intensity |
- Key mic on CTAF frequency (check Chart Supplement)
- Lights typically stay on for 15 minutes
- Re-key as needed during approach
- Works for runway, taxiway, and approach lights
Runway Lighting
| Light | Description |
|---|---|
| HIRL/MIRL/LIRL | High/Medium/Low Intensity Runway Lights - white, yellow last 2,000 ft |
| REIL | Runway End Identifier Lights - flashing white at threshold |
| Threshold Lights | Green from approach side, red from runway side |
| End Lights | Red from runway side |
| Centerline Lights | White, alternating red/white last 3,000 ft, red last 1,000 ft |
| TDZ | Touchdown Zone - white bars on each side |
Taxiway Lighting
| Light | Description |
|---|---|
| Taxiway Edge | Blue omnidirectional lights |
| Taxiway Centerline | Green lights |
| Clearance Bar | Yellow lights at holding positions |
| Stop Bar | Red lights - DO NOT CROSS unless cleared |
| Runway Guard Lights | Flashing yellow - elevated or in-pavement |
Key Takeaways
- Black hole approach over featureless terrain tempts a too-low approach — use VASI/PAPI and the altimeter.
- Autokinesis: a stationary light appears to move when stared at — avoid fixating, maintain a scan.
- False horizons and runway width/slope illusions distort attitude and approach — trust instruments.
- Somatogravic illusion on takeoff feels like pitch-up — don't push the nose down; reference the attitude indicator.
Night Flight Illusions
Visual illusions that can lead to spatial disorientation.
Black Hole Approach
Featureless terrain (water, dark areas) with only runway lights visible.
Danger: Tempts you to fly too low — no visual references to judge height.
Prevention: Use VASI/PAPI, monitor the altimeter, fly standard pattern altitude.
Autokinesis
A stationary light appears to move after you stare at it for several seconds.
Danger: Can cause disorientation or incorrect control inputs.
Prevention: Don't fixate on single lights; keep your instrument scan moving.
False Horizon
Sloping clouds, ground lights, or stars mistaken for the horizon.
Danger: Can lead to unusual attitudes or spatial disorientation.
Prevention: Trust instruments; cross-check the attitude indicator frequently.
Runway Width Illusion
A narrow runway looks farther away; a wide one looks closer.
Danger: You may fly too high (narrow) or too low (wide).
Prevention: Use VASI/PAPI, know the runway dimensions, hold pattern altitude.
Rain on Windscreen
Refraction through rain makes lights appear lower than they are.
Danger: Tempts a higher approach than necessary.
Prevention: Use VASI/PAPI; trust instruments over visual cues.
Bright Runway Lights
Bright lights look closer than dim lights at the same distance.
Danger: You may misjudge distance to the airport.
Prevention: Cross-check with instruments and VASI/PAPI.
Somatogravic Illusion (vestibular)
A vestibular (inner-ear) illusion — rapid acceleration (e.g., takeoff) feels like pitching up, even when attitude is level.
Danger: You may push the nose down in response — especially deadly on a night takeoff over dark terrain with no horizon.
Prevention: Trust instruments on takeoff; hold pitch on the attitude indicator until a visible horizon returns.
Key Takeaways
- Night currency (§61.57): 3 takeoffs and landings to a full stop within the preceding 90 days to carry passengers.
- Currency window: 1 hour after sunset to 1 hour before sunrise, same category and class.
- Required night equipment is FLAPS: Fuses, Landing light (for hire), Anti-collision, Position lights, Source of electricity.
- Night for logging is end of evening to beginning of morning civil twilight; position lights run sunset to sunrise.
Night Currency (14 CFR §61.57)
- 3 takeoffs and landings to a full stop
- Within preceding 90 days
- In same category and class of aircraft
- During the period 1 hour after sunset to 1 hour before sunrise
- Required to carry passengers at night
Night — three different time windows (don't conflate)
- Logging night time (§1.1): end of evening civil twilight to beginning of morning civil twilight
- Night-landing currency (§61.57): the 3 takeoffs/landings must fall 1 hour after sunset to 1 hour before sunrise
- Position & anti-collision lights (§91.209): sunset to sunrise
Required Equipment (14 CFR §91.205)
- Position lights (nav lights) - red left, green right, white aft
- Anti-collision lights (beacon/strobes)
- Landing light (if for hire)
- Adequate electrical source
- Spare fuses (if aircraft uses fuses)
- FFuses
- LLanding light
- AAnti-collision
- PPosition lights
- SSource of electricity
Key Takeaways
- Verify all position, landing, taxi, and anti-collision lights plus panel lighting before night flight.
- Carry a flashlight (red lens preferred) with fresh batteries, plus a backup.
- Allow 30 minutes for dark adaptation; use red cockpit lighting and avoid bright white lights.
- Plan routes over lighted areas, note moon phase, and have alternates with runway lighting.
Aircraft Checklist
- All position lights functional and visible
- Landing and taxi lights operational
- Anti-collision lights working
- Instrument and panel lights functional
- Flashlight with fresh batteries (red lens preferred)
- Backup flashlight
Pilot Checklist
- Allow 30 minutes for dark adaptation before flight
- Avoid bright white lights before/during flight
- Use red cockpit lighting when possible
- Get adequate rest - fatigue impairs night vision
- Carry charts with night-readable markings
- Review emergency procedures
Planning Checklist
- Check for TFRs and NOTAMs (lighting outages)
- Verify PCL frequency and operation
- Plan route over lighted areas when possible
- Know moon phase and available ambient light
- Have alternate airports with runway lighting
- File flight plan for added safety
Training aid only — verify all data against your POH and current FAA publications.