GRUMMAN AMERICAN
FOR TRAINING USE ONLY – SECTION 10
MODEL GA-7/COUGAR
SAFETY INFORMATION
10-9
Issued: April 10, 1978
MOUNTAIN FLYING
Avoid flight at low altitudes over mountainous terrain, particularly 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 strong up and down drafts and severe or extreme turbulence. The worst
turbulence will be encountered in and below the rotor zone which is usually 8 to 10 miles downwind from the
ridge. This zone is characterized by the presence of “roll clouds” if sufficient moisture is available; altocumulus
standing lenticular clouds are also visible signs that a mountain wave exists; but their presence is likewise
dependent upon moisture. Mountain wave turbulence can, of course, occur in dry air and the absence of such
clouds should not be taken as any 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, avoid “VFR On Top” and “Special VFR.” Being caught above an undercast when an
emergency descent is required (or at destination) is an extremely hazardous position for the VFR pilot. Accepting a
clearance out of certain airport control zones with no minimum ceiling and 1-mile visibility as permitted with
“Special VFR” is not a recommended practice for a VFR pilot.
Avoid areas of low ceilings and restricted visibility unless you are instrument proficient and have an instrument
equipped airplane, then proceed with caution and have planned alternates.
VFR AT NIGHT
When flying VFR at night, in addition to the altitude appropriate for the direction of flight, pilots should maintain a
safe minimum altitude as dictated by terrain, obstacles such as TV towers, or communities in the area flown. This
is especially true in mountainous terrain, where there is usually very little ground reference and absolute minimum
clearance is 2,000 feet. Don’t depend on your being able to see obstacles in time to miss them.
VERTIGO – DISORIENTATION
Disorientation can occur in a variety of ways. During flight, inner ear balancing mechanisms are subjected to
varied forces not normally experienced on the ground. This, combined with loss of outside visual reference, can
cause vertigo. False interpretations (illusions) result and may confuse the pilot’s conception of the attitude and
position of his airplane.
Under VFR conditions the visual sense, using the horizon as a reference, can override the illusions. Under low
visibility conditions (night, fog, clouds, haze, etc.) the illusions predominate. Only through awareness of these
illusions, and proficiency in instrument flight procedures, can an airplane be operated safely in a low visibility
environment.
Flying in fog, dense haze or dust, cloud banks, or very low visibility, with strobe lights, and particularly rotating
beacons turned on, frequently causes vertigo. They should be turned off in these conditions, particularly at night.
All pilots should check the weather and use good judgment in planning flights. The VFR pilot should use extra
caution in avoiding low visibility conditions.
Motion sickness often precedes or accompanies disorientation and may further jeopardize the flight.