i?eechcraft
Twin Engine (Piston)
MOUNTAIN
FLYING
Section X
Safety Information
Pilots flying in mountainous areas should inform themselves
of all aspects of mountain flying, including the effects of top-
ographic features on weather conditions. Many good articles
have been published, and a synopsis of mountain flying
operations is included in the FAA Airman's Information Man-
ual, Part 1.
Avoid flight at low altitudes over mountainous terrain, par-
ticularly near the lee slopes. If the wind velocity near the
level of the ridge is in excess of 25 knots and approximately
perpendicular to the ridge, mountain wave conditions are
likely over and near the lee slopes. If the wind velocity at the
level of the ridge exceeds 50 knots, a strong mountain wave
is probable with extreme up and down drafts and severe
tur-
bulence. The worst turbulence will be encountered in and
below the rotor zone, which is usually 8 to 10 miles down-
wind from the ridge. This zone is sometimes characterized
by the presence of "roll clouds" if sufficient moisture is
present; altocumulus standing lenticular clouds are also vis-
ible signs that a mountain wave exists, but their presence is
likewise dependent on moisture. Mountain wave turbulence
can, of course, occur in dry air and the absence of such
clouds should not be taken as assurance that mountain
wave turbulence will not be encountered. A mountain wave
downdraft may exceed the climb capability of your airplane.
Avoid mountain wave downdrafts.
VFR -
LOW
CEILINGS
If you are not instrument rated, do not attempt "VFR on
Top"
or "Special VFR" flight or clearances. Being caught above a
solid cloud layer when an emergency descent is required (or
at destination) is an extremely hazardous position for the
VFR pilot. Accepting a clearance out of airport control zones
with no minimum ceiling and one-mile visibility as permitted
with "Special VFR" is a foolish practice for the VFR pilot.
May, 1994
10..39
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