MOUNTAIN FLYING
There are several texts available. The following is from “Mountain Flying” by Sparky Imeson.
1. PREFLIGHT
A thorough weather briefing is mandatory. Keep in mind that mountain weather can change
rapidly. If no weather is reported for your route or destination, a phone call to enroute and your
destination airport is in order. Have good VFR weather for your route. Surface winds of 20
knots or more, and winds aloft over 20 knots dictate caution. Winds aloft of 30 knots or more
are a no-go. Increasing wind implies turbulence. If encountered, slow to maneuvering speed.
Current charts are required. Routes that keep you within gliding distance of a suitable landing
spot are preferred. Mountain Wave effect suggests a route on the windward side. Know your
airplane’s performance intimately. Compute Density Altitude and lean the mixture accordingly.
A sloped runway generally dictates an uphill landing and downhill takeoff, providing the
tailwind component is not too great. Plan early morning flights to take advantage of cooler,
smoother air. Carry plenty of reserve fuel, calculate weight and balance, keep gross weight at
least 10% under maximum.
2. TAKEOFF
Know your density altitude and compute takeoff distances. High density altitude may require
delaying takeoff until cooler temperatures prevail. Mixture must be adjusted to obtain maximum
power and RPM. Rotate at Vx, climb at Vx if obstacles must be cleared, and then Vy. Vy
decreases with altitude (Vx increases) until they meet at the service ceiling (about best glide
speed). The takeoff distance will be increased with altitude due to an increased TAS and GS.
Use the same indicated airspeed you use at lower altitudes. Be alert to rapidly rising terrain.
3. ENROUTE
Always be in a position where you can turn to lower terrain in the event of downdrafts or power
failure. Try to maintain 2000’ above all terrain. Mixture must be leaned with increasing altitude
for best power/RPM. Be aware of false horizons created by sloping terrain. Avoid flight when
lenticular clouds are present, they represent mountain wave activity and turbulence. They may
or may not be present when winds aloft are strong. Avoid rotor clouds found leeward, at or
below mountaintop due to severe turbulence. If turbulence and downdrafts are encountered on
the lee side, turn back early. Approach a ridge on the lee side at a 45 degree angle so only a 90
degree turn or less is required to lower terrain if downdrafts occur. Higher altitudes mean colder
temperatures, dress warmly. Be prepared for adverse weather survival if a forced landing occurs.
Pack survival equipment. Oxygen is required between 12,500 and 14,000 feet after ½ hour, all
the time above 14,000’. Some people may require oxygen at lower altitudes. Most of Colorado
can be flown at or below 12,500’, going to 14,000’ briefly to cross passes. Be aware of the
symptoms of hypoxia, and use oxygen or get to lower levels early. It is best to stay well above
canyons, but if necessary, fly the updraft side. Fly up canyons with sufficient altitude to cross
the ridge at the head of the canyon. Otherwise you may find the terrain out-rising your climb
speed. Never fly a canyon without adequate room to turn around. Also there may be wires
strung across a canyon. Again, fly at or below maneuvering speed if turbulence is encountered.
4. ARRIVAL
Climbs, and especially descents, may cause discomfort in the ears due to pressure changes. Be
knowledgeable about techniques to clear the ears, and be wary of young children who may not
be able to understand these techniques. Plan your descent to avoid rapid power reductions and
shock-cooling the engine. Know your destination airport and surrounding terrain. Some canyon
airports are “one way” due to terrain. The approach may have no resemblance to a normal
pattern due to terrain. If unfamiliar, fly over the airport at altitude to check the terrain, and for
traffic and animals. This will show you the best way to approach. You will know where the
airport is when it is obscured by terrain on the approach. “One-way” airports may not allow for
a go-around, so plan and fly your approach and landing carefully.
5. LANDING
It is common at high altitude airports to approach with excessive airspeed. Remember the same
indicated airspeed is used as at lower airports. This will result in a higher true airspeed. You
may add ½ the gust factor if windy, just as you would at lower altitudes. Control your speed and
touchdown point, as the higher TAS and GS will require a longer landing rollout. At higher
altitudes, it will take a higher power setting to achieve the sane rate of descent you’re used to at
lower altitudes. Touch-and-go’s are undesirable due to the long landing and takeoff rolls. If a
go-around is required, do it early. Excessive approach speed translates into a long float in
ground effect, and a long landing. Landing uphill creates the illusion of a nose low attitude and
being higher than you are. Brush up on your short-field technique.
6. DO’S AND DON’TS
File a flight plan.
Thoroughly check weather. Go only when good and winds are light.
Be familiar with aircraft performance.
Follow the lowest terrain; always have a suitable place to land.
Fly appropriate indicated speeds.
Use an aircraft with power appropriate to the weight you want to carry.
Rules of thumb:
Less than 200 HP: 2 people, little baggage.
More than 200 HP: 3 people, little baggage.
Stay at least 10% under maximum gross weight.
Get a thorough mountain check-out; always check with an experienced mountain pilot.