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depending upon the amount of light on the surface.
This can happen on the sunniest, brightest day with
good contrast everywhere. However, when it
happens, there can be a complete loss of visual clues.
If the pilot has not prepared for this immediate loss of
visibility, the results can be disastrous. Good
planning does not prevent one from encountering flat
light or white out conditions.
d. Never take off in a white out situation.
1. Realize that in flat light conditions it may be
possible to depart but not to return to that site. During
takeoff, make sure you have a reference point. Do not
lose sight of it until you have a departure reference
point in view. Be prepared to return to the takeoff
reference if the departure reference does not come
into view.
2. 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.
3. So what should a pilot do when all visual
references are lost?
(a) Trust the cockpit instruments.
(b) Execute a 180 degree turnaround and start
looking for outside references.
(c) Above all − fly the aircraft.
e. 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.
f. Airport Landings.
1. 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.
2. Be cautious of snowdrifts and snow banks −
anything that can distinguish the edge of the runway.
Look for subtle changes in snow texture or shading to
identify ridges or changes in snow depth.
g. Off−Airport Landings.
1. In the event of an off−airport landing, pilots
have used a number of different visual cues to gain
reference. Use whatever you must to create the
contrast you need. Natural references seem to work
best (trees, rocks, snow ribs, etc.)
(a) Over flight.
(b) Use of markers.
(c) Weighted flags.
(d) Smoke bombs.
(e) Any colored rags.
7/31/08 AIM
AIM 2/14/08
7−5−12 Potential Flight Hazards
(f) Dye markers.
(g) Kool−aid.
(h) Trees or tree branches.
2. It is difficult to determine the depth of snow
in areas that 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 landing. Never put yourself in a
position where no visual references exist.
3. 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.
4. Exercise extreme caution when flying from
sunlight into shade. Physical awareness may tell you
that you are flying straight but you may actually be in
a spiral dive with centrifugal force pressing against
you. Having no visual references enhances this
illusion. Just because you have a good visual
reference does not mean that it’s safe to continue.
There may be snow−covered terrain not visible in the
direction that you are traveling. Getting caught in a no
visual reference situation can be fatal.
h. Flying Around a Lake.
1. When flying along lakeshores, use them as a
reference point. Even if you can see the other side,
realize that your depth perception may be poor. It is
easy to fly into the surface. If you must cross the lake,
check the altimeter frequently and maintain a safe
altitude while you still have a good reference. Don’t
descend below that altitude.
2. The same rules apply to seemingly flat areas
of snow. If you don’t have good references, avoid
going there.
i. Other Traffic. Be on the look out for other
traffic in the area. Other aircraft may be using your
same reference point. Chances are greater of
colliding with someone traveling in the same
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