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Aviation Learning Center Document Flying in Flat Light and White Out Conditions
Author: FAA Date: 2001
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Raising the Margin of Safety
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When a pilot has degrading visual cues, the following equipment can assist in raising the margin of safety:

  • Artificial horizon
  • Vertical speed indicator
  • Heading indicator
  • Advanced instrumentation
  • Radar altimeters
  • Global positioning system (GPS)
  • Pressure sensitive altimeter
  • VHF omnirange (VOR) system
  • Anything else that may be of assistance to you (i.e. colored glasses)

Flat light is common to snow skiers. One way to compensate for the lack of visual contrast and depth-of-field loss is by wearing amber tinted lenses (also known as blue blockers.) Special note of caution: Eyewear is not ideal for every pilot. Take into consideration personal factors: age, light sensitivity, and ambient lighting conditions.

So what should a pilot do when all visual references are lost?

  • Trust the cockpit instruments
  • Execute a 180-degree turnaround and start looking for outside references
  • Above all, fly the aircraft

Landing in Low Light Conditions

When landing in a low light condition, use extreme caution. Look for intermediate reference points, in addition to checkpoints along each leg of the route for course confirmation and timing. The lower the ambient light becomes, the more reference points a pilot should use.

Airport Landings

Look for features around the airport or approach path that can be used in determining depth perception. Buildings, towers, vehicles or other aircraft serve well for this measurement. Use something that will provide you with a sense of height above the ground, in addition to orienting you to the runway.

Be cautious of snowdrifts and snow banks - anything that can distinguish the edge of the runway. Look for subtle changes in snow texture to identify ridges or changes in snow depth.

Off-Airport Landings

In the event of an off-airport landing, pilots have used a number of different objects to gain reference. Use whatever you must to create the contrast you need. Natural references seem to work best (trees, rocks, snow ribs, etc.)

  • Overflight
  • Use of markers
  • Weighted flags
  • Smoke bombs
  • Red shop bags
  • Dye markers
  • Kool-aid
  • Trees or tree branches

It is difficult to determine the depth of snow and what areas are level. Dropping items from the aircraft to use as reference points should be used as a visual aid only and not as a primary landing reference. Unless your marker is biodegradable, be sure to retrieve it after use.

Never put yourself in a position where no visual references exist.

Abort landing if blowing snow obscures your reference. Make your decisions early. Don't assume you can pick up a lost reference point when you get closer.

Exercise extreme caution when flying from sunlight into shade.

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