Night Operations in VFR Flying
1. Factors related to Night Vision
- It is important to note, if humans learn to use their eyes correctly and know their limitations, night vision can be improved significantly.
- Eyes are used differently at night, therefore it is important to understand the eyes construction/how it is affected by darkness.
Light Sensitive Nerves: connects images to optic nerve that transmit messages directly to the brain.
- Cones – located in the center of the retina. Detect color, detail, and faraway objects.
- Rods – Concentrated in a ring around the cones.
o Function when something is seen out of the corner of eye or peripheral vision.
o Detect moving objects, but do not give detail or color – only shades of grey.
- Daylight – cones and rods used for vision.
- Nighttime – process of night vision placed almost entirely on rods.
- Daylight – object can be seen best by directly
looking at it.
- Nighttime – rods are distributed in a band
around the cones and do not lie
directly behind the pupils. This
makes “off center” viewing
(looking to one side of the object)
important during night flight.
Eyes Adaptation to Darkness:
- When you enter a dark room, it is difficult to see anything until your eyes have become adjusted. Pupils enlarge to receive as much of the available light as possible.
- 5-10 min – cones become adjusted to dim light, eyes become 100 times more sensitive.
- 30 min – rods become adjusted to darkness, eyes become 100,000 times more sensitive.
- If exposed to light, entire process is reversed and eyes become adjusted to brightness in just a few seconds. Eyes have to go through a long process again to adjust to darkness.
Pilots Role in Adaptation Process:
- Eyes should be allowed to adapt to a low level of light first.
- After adaptation complete, pilot should avoid bright white light that could cause temporary blindness or have serious consequences.
- Temporary Blindness – may result in illusions such as vertigo (feeling of unbalance or dizziness), misjudging or identifying objects. Recognizing illusions is best protection against night flying.
1. Bad physical condition
4. Vitamin Deficiency
Increasing Night Vision Effectiveness:
- Adapt eyes to darkness for about 30 minutes prior to flight.
- Use oxygen if available. Vision can be impaired at cabin altitudes as low as 5000ft.
- Close one eye when exposed to bright light.
- Do not wear sunglasses after sunset.
- Move eyes slower than during daylight.
- Blink eyes if they become blurred.
- Concentrate on seeing objects.
- Force eyes to view off center.
- Maintain good physical condition.
- Avoid smoking, drinking, and using harmful drugs.
2. Night Illusions
- Can cause confusion and concern during night flying.
- Distance lights can be mistaken for stars or other aircraft.
- Northern lights can even confuse pilot and indicate a false horizon.
- Geometrical patterns of ground lights such as a freeway, runway, approach, or moving lights can even cause confusion.
- Tends to eliminate reference to a visual horizon.
- Pilot needs to rely less on outside reference and more on flight/nav instruments.
- Occurs when pilot states at a single light source and it appears to move.
- Corrective Action – expand visual field and do not fixate on one source of light.
- Caused by flickering light in the cockpit, anti-collision light, strobe lights, or other a/c lights.
- Physical reactions – nausea, dizziness, grogginess, unconsciousness, headaches, confusion.
- Corrective Action – eliminate light source causing the flickering.
Black Hole Approach:
- Occurs when landing and runway lights are the only source of light.
- Without visual cues pilots have trouble orientating themselves to earth and runway can seem out of position (upsloping, downsloping, landing short of runway).
- Corrective Action – Electronic glideslope, VASI, or Go-around
Bright Runway Lights:
- Makes runway appear closer.
- Can make aircraft seem higher in a turn to final, than when its wings are level.
Conclusion: Make sure you review airfield layout and boundaries before initiating any approach.
4. Pilot Equipment (Flash light)
- At least one reliable flashlight.
1. White light source – preflight
2. Red light source – performing cockpit operations since it is nonglaring. Will not impair night vision. Two flashlights or a bulb switching mechanism for colors. Caution – red light used for reading an aeronautical chart will cause red features of chart not to show up.
- Spare set of batteries.
- Aeronautical Charts - lights of cities and towns, identifying landmarks. Have adjacent if chart if course if close.
Airplane Equipment and Lighting
- Basic Minimum Airplane Equipment (91.205)
-A Tomato Flames plus:
Landing Light – if for hire
Anti-collision Light – strobes or rotating beacon
Source of Electrical Power
- Standard instruments required for IFR are a valuable asset for aircraft control at night.
- Red light – positioned on left wingtip.
- Green light – positioned on right wingtip.
- White light – positioned on tail.
- Position lights provide a means to determine general direction of movement of other airplanes.
- Landing Lights – useful for taxi, takeoff, landing and collision avoidance. Pilots encouraged to turn on within 10 miles of airport day or night and reduced visibility.
Conclusion: Pilots cannot become complacent. Aircraft lights can blend in with stars or lights.
Airport and Navigation Lighting Aids
- Important to be able to identify airports by characteristics of their lighting pattern.
- The following includes only lights that are fundamental to VFR night operations.
- Pilot must check the availability and status of lighting systems
1. Aeronautical charts
2. Airport/Facility Directory
3. NOTAM’s – for status
- Used to indicate location of most airports.
- Lighted civilian land – alternating white and green.
- Lighted civilian water – alternating white and yellow.
- Light military – alternating white and green with two dual peaked white flashes.
- Red flashes – indicate obstructions or areas hazardous to aerial navigation.
- Steady red – mark obstructions on or near airports.
- Flashing white lights – some supporting structures (transmission lines, tall structures such as
chimneys and towers).
VFR Runway Lighting Systems:
- Runway edge lights – define lateral limits of runway. Colored aviation white while yellow
may be used for last 2,000 feet from end of runway to indicate caution
- Threshold – straight line of green lights marking beginning of runway.
- Runway end lights – aviation red. Straight line of lights marking end of runway.
- Taxiway edge lights – consists of blue lights that outline usable limits of taxi paths.
Preparation and Preflight
- Pilots must operate within their own abilities and limitations at night.
- Demands more attention to the details of preflight preparation and planning.
- Temperature/dew point spread – narrow spread indicates possibility of ground fog.
- Wind direction/speed – cannot be detected as easily as during the day.
- Course lines should be drawn in black to be more distinguishable.
- Prominently lighted checkpoints should be noted.
- Use of radio navigation and communication aids.
- Checked for proper functioning.
- Turned on and checked for operation. Tap positions lights (blink) indicate loose connect
- Should be examined prior to entering aircraft (ladders, chocks, other obstructions).
Starting, Taxiing, and Runup
- Extra caution taken at night to ensure cockpit items readily available/convenient to use.
- Propeller area – extra caution to assure clear. Beacon or position lights should be on to
signal starting and tell people to remain clear.
- Electrical current – avoid unnecessary drain of battery until engine has been started.
- Taxi or landing light – should be turned on. Consideration given to blinding other pilots.
1. Continuous use of landing light with low taxi rpm settings could place excessive drain on electrical system.
2. Overheating of landing light could be a problem due to inadequate airflow to carry away heat.
- Taxi – slowly in congested areas and follow taxi lines to ensure proper path along route.
- Day – pilot is aware to aircraft creeping forward.
- Night – could creep forward without being noticed unless pilot is alert for possibility.
- Caution: Hold or lock brakes and be aware for any forward movement.
Takeoff and Climb
- Should be used to a greater degree at night since limited outside reference.
- Should be adjusted to a minimum brightness so that pilot can read instruments but not hinder outside references.
1. Cleared for takeoff – landing/taxi lights should be turned ON.
2. Airplane aligned with centerline – heading indicator noted or set to correspond.
- Procedure for night takeoffs are the same as day except that many visual cues not available. Flight instruments should be checked frequently during takeoff to ensure proper pitch attitude, heading and airspeed. Pitch attitude should be accomplished by referring to both inside and outside references, such as lights, and to the flight instruments.
- Darkness of night makes it difficult to tell distance above surface.
- Be sure a climb in indicated on attitude indicator, VSI, and altimeter.
- Pitch and bank – adjustments should be made by referencing attitude and heading ind. No
turns until reaching a safe altitude.
- Landing light – may be turned off after climb established or kept on for collision avoidance.
Orientation and Navigation
Clouds/restrictions to visibility:
- VFR must exercise extreme caution to avoid flying into clouds at night (particularly dark nights and overcast).
- Restricted visibility – first indication is gradual disappearance of lights on the ground.
- Ground fog – lights start to take on appearance of being surrounded by halo or glow.
Remember horizontal visibility is much less than looking through vertically.
- Marginal weather conditions – under no circumstances should a VFR flight be made in
marginal weather conditions at night unless the pilot/aircraft
are IFR equipped.
- Pilot should practice BAI, steep turns, and recovery from unusual attitudes (dual flight). Cockpit lights should also be turned off periodically to simulate an electrical failure.
- References/checkpoints – fewer so pilot must monitor position, time estimates, and fuel.
- NAVAIDS – if available should be used to monitor en route progress.
- Large bodies of water – potentially hazardous due to lack of depth perception/horizon blend
Approaches and Landings
Approaching the Airport:
1. Runway lights/airport lighting must be identified as early as possible.
2. Fly toward rotating beacon until runway lights are distinguishable.
3. Pattern – to fly properly runway edge lights/threshold must be identified.
Judgment of Speed/Altitude:
- Becomes difficult with less ground references so more dependence must be placed on the instruments (particularly altimeter and airspeed indicator).
Entering the Traffic Pattern:
1. Allow plenty of time to complete before landing checklist.
2. Set heading bug to runway heading – excellent reference for pattern legs.
1. Should maintain same airspeeds/approach as during the daytime.
2. Low shallow approach is NOT appropriate for night landing.
3. Constantly cross check altimeter and VSI.
- VASI – indispensable aid in establishing/maintaining glidepath at night.
1. Align airplane midway between two rows of runway-edge lights.
2. Note and correct for any wind drift.
3. Pitch and power used to maintain a stable approach.
4. Flaps should be used same as in a normal approach.
5. Landing light on if not already accomplished.
Roundout and Touchdown:
- Should be made in same manner as day landings.
- Judgment of height, speed, and sink rate is obscured by lack of visual references.
- Inexperienced pilot may roundout to high until familiar.
Aid in proper roundout:
1. Constant approach descent.
2. Begin roundout when landing lights reflect on runway and tire marks can be seen clearly.
3. At this point, roundout should be made smoothly and throttle reduced to idle as airplane is touching down.
No Landing Light:
1. Roundout may be started when runway lights at far end of the runway appear to be rising higher than the nose of the airplane.
2. Requires pilot to make smooth roundout and feel for runway surface using power/pitch.
- Maintain positive control.
- Best glide configuration and airspeed.
- Turn toward airport or away from congested area.
- Determine cause of malfunction/fix.
- Announce the emergency situation.
- Maintain orientation with the wind.
- Complete before landing checklist/landing light on.
Landing should be completed in normal landing attitude at slowest possible airspeed. If outside references unavailable, the airplane should be held in level landing attitude until ground in contacted. Then turn off all switches off and evacuate.