BY ORDER OF THE SECRETARY OF THE AIR FORCE AIR FORCE ...

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AFMAN 11-217V1 3 JANUARY 2005
a blinding effect at night. The transition from an approach in a total obscuration
involves the integration of visual cues within the crosscheck during the latter
portion of the approach. Again, be thoroughly familiar with the approach lighting
system to develop the proper perspective between these cues and the runway
environment.
15.2.4.1.3. Fog Below Clouds. This fog is usually reported as a partial
obscuration below a cloud ceiling. After penetrating through a ceiling, visibility
usually increases when you descend below the cloud ceiling. Therefore, the
transition from instrument to visual flight is sharper, with more pronounced use of
visual cues after passing the ceiling. However, with fog below clouds all of the
problems mentioned above with shallow fog and deep fog may be found. Night
approaches may produce the sensation that the aircraft is high once the cloud base
is passed. You should continue on instruments, cross-checking visual cues to
confirm runway alignment. During the flare you may experience a sensation of
descending below the surface of the runway. This will be especially pronounced
at facilities with 300-foot wide runways. In either case, avoid abrupt or large
attitude changes.
15.2.4.1.4. Advection Fog. Advection fog can present wind and turbulence
problems not normally associated with other types of fog. Advection fog may
possess characteristics similar to shallow, deep, or cloud base fog. It may be
more difficult to maintain precise instrument flight because of turbulence. The
characteristics of advection fog will be related to the wind speed increases. Wind
greater than 15 knots usually lifts the fog and it forms a cloud base. The best
procedure is to be aware of the conditions that might be encountered and to
integrate visual cues within the crosscheck during the later portion of the
approach. Also closely monitor airspeed because of the effects of turbulence and
crosswinds.
15.2.4.1.5. Ice Fog. This type of fog is most common to the Arctic region;
however, it can occur in other areas if the air temperature is below approximately
0° C (32° F). It consists of a suspension of ice crystals in the air and is more
common around airports and cities. Condensation nuclei caused by human
activity often cause the fog to form. When there is little or no wind, it is possible
for an aircraft to generate enough fog during landing or takeoff to cover the
runway and a portion of the field. Depending on the atmospheric conditions, ice
fogs may last for several minutes or days. The piloting hazards and procedures
are basically the same as with other fogs.
15.2.4.1.6. Rain. Approaches and the ensuing transition to visual flight can be
very hazardous since moderate to heavy rain conditions can seriously affect the
use of visual cues. Night approaches in these conditions can be even more critical
as flashing strobes or runway end identifier lights may distract you. Transition to
visual flight can be severely hampered by the inability to adequately maintain
aircraft control and interpret the instruments as a result of gusty or turbulent
conditions. The moderate or heavy rain conditions can also render the rain
removal equipment ineffective, causing obscuration of visual cues at a critical
time during the transition. In these conditions, be prepared for an alternate course