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Mountain Flying

Weather and flight planning

Downdrafts & updrafts
Turbulence, Rotors, Wind Shear
Density Altitude

Aircraft Performance

Ground Speed and TAS vs. IAS

Oxygen
Emergency Gear

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Mountain Flying

The Flight

Takeoff
Landing
Clearing Mountains
Forced Landings
Course Reversal
The Route

Controlled Flight into Terrain (CFIT)
WX Resources

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Weather and Flight Planning

Mountain weather can change rapidly

Check forecasts
Contact Flight Watch (122.0) often

Colder temps ⇒ greater chance for icing
Fly early morning or late afternoon for lightest winds.

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Weather and Flight Planning

VFR over high terrain may be impossible

Even though your departure/destination airports are experiencing good weather.

Colorado Pilots Association recommends at least 15 Miles visibility.

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Weather and Flight Planning

Mountain flying is not a guaranteed go

Check the forecast, and then test the waters
If you like what you see initially, proceed
If not, turn back
Don’t get fixated on completing the flight

Don’t go if the weather is doubtful

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Weather and Flight Planning

In general…

multiple airports = multiple flight plans

If you go down between two airports, search crews have much better SA
If a leg more/less time, the clock is reset with the next flight plan

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Weather and Flight Planning

Know the winds aloft and winds at destination airports
Try to plan your route to fly on upwind side of valleys and canyons
Always try know where the wind is coming from

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Wind and Visual Indicators

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Wind and Visual Indicators

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Weather and Flight Planning

Lenticular clouds = extreme turbulence
Mountain waves can extend for tens or hundreds of miles
In heavy turbulence, fly an attitude and accept altitude loss

Don't over-stress the airframe

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Weather and Flight Planning

Don’t rely on clouds for wind direction

Expect wind to be constantly changing in direction and velocity because terrain

Don’t fly the middle of a canyon

Puts you in a poor position to make an escape and subjects you to shear turbulence
Fly on the side of canyons to catch updrafts

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Weather and Flight Planning

Rotors/wind shear are basically guaranteed at 20 kts

Especially on the lee side of a peak/ridge

Try to visualize possible downdraft areas

Air behaves like water
Ask yourself, "What would water do if it were flowing like the winds aloft?”

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Weather and Flight Planning

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Weather and Flight Planning

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Weather and Flight Planning

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Weather and Flight Planning

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Weather and Flight Planning

The venturi effect in mountain passes can increase wind velocity significantly

This can produce winds in passes that are much stronger than winds aloft
Expect wind to be much greater velocity over mountain passes than reported in areas a few miles away

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Weather and Flight Planning

Winds aloft greater than 30 knots at cruise altitude usually means the novice pilot should delay or postpone the flight until more favorable conditions prevail

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Weather and Flight Planning

Three factors affect air density:

Altitude
Temperature
Humidity

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Weather and Flight Planning

Calculate density altitude before flight

DA is the altitude the airplane thinks it is at and performs accordingly
High, hot, and humid conditions may ‘raise’ an airstrip thousands of feet higher

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Aircraft Performance

Be familiar with aircraft performance; service ceiling, to/land distance, climb rate

Normally aspirated engines…

Lose ~3% of HP/1K’ above SL
HP is decreased since fuel/air mixture is reduced
Max power you can generate at 7500’ is 75%

Propeller develops less thrust
Wings develop less
Takeoff distance is increased
Climb performance is reduced

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Aircraft Performance

Vy decreases with altitude

ROT: subtract 1kt for every 1K’ of DA

Vg decreases as weight decreases

ROT: Vg decreases 2kts for every 10% under maximum gross weight

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Aircraft Performance

Weight and density altitude are the most important factors when determining airspeed for best rate of climb & best glide

Learn to interpolate to figure the proper performance data before you need it

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Aircraft Performance

Don't use short field flap settings for high density altitude takeoffs

Unless the field is truly short
Short field flap settings give a better angle, not rate of climb
At the typically long high-elevation airports flaps will be a hindrance to reaching Vy

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Aircraft Performance

Being light is a good way to compensate for lower power

As a rule of thumb, being 10% under maximum gross weight provides a 20% performance benefit over the POH numbers

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Ground Speed & TAS vs. IAS

Roughly, TAS increases by 2% over IAS for every thousand feet altitude gain

At 10,000’, TAS will be ~ 20% higher
This is a built-in compensator for reduced lift caused by the thin air at high airports
Since TAS is higher, fly a wider pattern
Ground speed will be much higher

Visual queues will be very different

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Oxygen

DA can be much higher than indicated

The effect of altitude on your body depends on the partial pressure of oxygen
Altimeters show pressure altitude

USAF recommends oxygen starting at 8K’
FAA regulations:

Not required until 12500 (still recommended)
Between 12500 – 14000, after ½ hour
Higher than 14000, continuous
Higher than 15000, must be provided for passengers

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Oxygen

Night vision inhibited > 5K’ pressure alt
Cannulas can't be used above 18000'

Manufacturers prohibit use
18K’ to 25K’ you can use an oxygen mask

Regulators / flow meters fail, valves freeze, and lines plug…always be ready to descend

Because of the risk, plan at flight at 16K’ vs. 22K’.

Time of useful consciousness at 20K’ is 30 min
At 22K’, time of useful consciousness is ~10 min

Also known as EPT, or Effective Performance Time

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Oxygen

Oxygen bottles are normally low pressure

500 PSI

1800 PSI is most common high pressure

The 1800 PSI bottles are green

Bottles need to be re-certified every 5 yrs

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Oxygen

Good idea to consider oxygen for flights > 5K’ (night) and > 8K’ (day)
Use of pulse oximeter

ROT: never let your oxygen saturation level get more than 10 percentage points below your ground level saturation level

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Emergency Gear

Warm clothes
Blankets or sleeping bags
Food
Water
Flashlights
Fire starter
Radio
Signaling mirror
Maps
Compass
Wear or bring shoes you can use for hiking
Always bring emergency gear when flying in the mountains

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The Flight

Assume sever wind sheer is present with any two or more of these conditions:

Extreme variations in wind velocity and direction in relatively short time
Evidence of a gust front such as blowing dust on an airport surface
Surface temps in excess of 80° F
Dew point spread of 40° F or more
Virga (precipitation that evaporates before hitting the ground)

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The Flight – Takeoff

Before landing, make sure you can get out

One technique – overfly the field at ~1500’ AGL and apply full power

If you can’t get at least 300fpm of climb, you probably shouldn’t land

ROT: if you have 70% of rotation speed by 50% of the runway, takeoff should be assured

Calculate beforehand / add to pre-takeoff briefing
VR=55kts – need to obtain 39kts at ½-way point

Treat 50% point as a binary abort point

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The Flight – Takeoff

Before takeoff, LEAN for max power

Direct drive engine and fixed pitch propeller

Hold the brakes, apply full throttle, lean to peak RPM (or 50˚ – 100˚ rich of peak EGT).
Leave mixture at that position for the takeoff

Constant speed propellers

Leaning is normally done using the EGT
See your POH for procedures

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The Flight – Takeoff

Takeoff distance varies with gross weight

A 10% increase in gross weight will cause:

5% increase in speed required for takeoff
9% decrease in acceleration
21% increase in takeoff distance

You may not want full fuel on takeoff from a high-altitude airport

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The Flight – Takeoff

ROT: each 1K’ above SL, takeoff distance increases approximately 25%

Normally aspirated engines

At 10,000 feet, about one-half of horsepower is lost
Example: Denver; field elevation indicated on the altimeter is 5000 ft; but at 80˚F, the DA is 7500’

Takeoff distance will be 2.3 times the sea level takeoff roll.

The double whammy: must be at a higher true airspeed to fly, but with an engine making less horsepower

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The Flight – Landing

Landing at a short mountain strip requires exact airspeed control to eliminate float

A 10% increase in the proper approach speed results in a 21% increase in landing distance
BE ON SPEED!

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The Flight – Landing

Richen mixture for go-around

Momentarily increase to full power when close to pattern altitude
Make sure you have enough time to loose the airspeed you’ve gained
Richen to 50˚ – 100˚ rich of peak EGT

(50˚ is good for small engines, 100˚ for high performance)

An altitude, cruise power may be max power

If so, mixture is already set & should work for landing

See your airplane’s POH for recommended leaning procedures

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The Flight – Landing

"The most common problem for flatlanders is the tendency to fly the approach below the normal indicated airspeed for landing. Thus, an area of heavy emphasis for mountain flying is to fly by the numbers and approach to land at the normal indicated airspeed.“� - Colorado Pilots Association

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The Flight – Landing

For safety from eddies, wind shear, and gusty conditions, plan approach using the runway numbers as your aim point

Flare 500 feet down the runway, and try to touch down on the 1,000’ markings
High altitude runways are usually long which provides a buffer against a severe downdraft

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The Flight – Landing

Use the same indicated airspeed at high-altitude airports as any airport

Takeoff and landing

Remote airports?

First overfly the field to check for wildlife and runway conditions

If you haven’t landed in the first half of the runway, you should abort the landing

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The Flight – Landing

Runway Illusions:

You’ll feel high due to narrow runways
Eyes tend to focus on rising terrain/ridges

You can be high if a hill is near the runway

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The Flight – Landing

Sloping runways are common in mountains

This can create illusions of being too high (upslope) or too low (downslope)
Slopes also affect takeoff / landing distance
This can be significant at mountain airports

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The Flight – Reading the Mountains

AVOID DOWNDRAFT

SIDE

FLY UPDRAFT

SIDE

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The Flight

Common mistake – flying in the center

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The Flight

If lift (updrafts/downdrafts) is not a factor, fly on the appropriate side of the valley so that your 180˚ exit turn can be made into the wind

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The Flight

Downdrafts on lee side of mountain
Updrafts on windward

If caught in a downdraft, look for an area where the wind may be rising
Find rising air and then perform shallow turns to remain in the updraft

It may be necessary to fly to a windward slope or some distance downwind before you can establish a positive rate of climb

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The Flight

If caught in a downdraft

Apply max power (and lean for best power)

Do not pull up!

It’s very common for people to pull up and then stall or enter a spin
People will often pull up and try to increase rate of turn by adding rudder
This is a perfect recipe for entering a spin at high altitudes

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The Flight

Fly away at Va

This may increase rate of descent, but it will exit the downdraft as quickly as possible
The further from a ridge, the less turbulence and downdrafts you will experience

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The Flight

Most accidents caused by downdrafts are due to pilot's concern about altitude loss

Don’t try to out-climb a downdraft
Instead, try to escape away from the ridge that is causing the downdraft

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The Flight – Clearing Mountains

The visual aspects of mountain flying can be deceiving

If you can see more and more of the terrain on the other side of a ridge, you are higher than the ridge and can probably continue

Plan every ridge crossing as though an engine failure was imminent

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The Flight – Clearing Mountains

Realize the horizon is near the base of the mountains

The mistake of using the summit of the peaks as the horizon will result in the aircraft being placed in an attitude of constant climb
This could inadvertently lead to stall from which a recovery may be impossible

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The Flight – Clearing Mountains

When approaching a ridge:

Inbound: fly at 45˚ angle when ¼ to ½ mile out
Outbound: fly straight out (90˚ angle)

Get away as quickly as possible

Downdrafts can be smooth or rapid/jolting

Monitor the VSI

A typical downdraft will produce a 1000 to 1500 fpm descent

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The Flight – Clearing Mountains

Establish 2-3K' clearance over mountains

Plan to cross mountains at least 2K feet above the highest point along the route
Altitude should be attained well in advance

Terrain can rise faster than the aircraft climb rate

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The Flight – Clearing Mountains

BASIC PREMISE #1

Always remain in a position where you can turn toward lowering terrain
This axiom also encompasses the idea that you will not enter or fly in a canyon where there is not sufficient room to turn around. Another way of stating this truth is to have an escape route in mind and be in a position to exercise this option.

Sparky Imeson “The Mountain Flying Bible”

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The Flight – Clearing Mountains

BASIC PREMISE #2

Do not fly beyond the point of no return.
This is the position when flying upslope terrain where, if you reduce the throttle to idle and begin a normal glide, you will have sufficient altitude to turn around without impacting the terrain.
As you near the ridge, when arriving at a position where the power can be reduced to idle and the airplane will glide to the top of the ridgeline, a commitment to cross the ridge can be made.
At this position, the airplane is close enough to the ridgeline not to experience an unexpected downdraft of a nature that will cause a problem.
If a downdraft is encountered, keep the power on, lower the nose to maintain airspeed and the airplane will clear the ridge.

Sparky Imeson “The Mountain Flying Bible”

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The Flight – Course Reversal

Everyone flying in the mountains will encounter situations when it becomes necessary to make a 180˚ turn

To turn around, slow down (decreases radius)
Trade airspeed for altitude (if you have it)
Make the steepest turn you can comfortably make (up to 60 degrees)

Course reversal in IMC to arrive at the same spot; turn 90˚ followed by 270˚

An 80˚ / 260˚ also works

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The Flight – Course Reversal

If you need a tight turn 🡪 slow down

Provides more reaction time
Creates a smaller radius

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720’

370’

400’

220’

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The Flight – Course Reversal

Decide on a turn and prepare for it before the situation become critical.
Fly as close as practical to the upwind side of the canyon.

Slow to flap extension speed and deploy “lift flaps” (~ 20° or mid-range)

Turn at 45° (min) towards middle of canyon and apply full power. Ok to glance at attitude indicator (don’t stare).

Pull back on the elevator and expect to hear the horn. If you feel a buffet, you’re pulling too hard.

720’ vs 370’ vs 220’

Let your nose drop as needed to avoid a stall. You’re turning towards lower terrain, so you have room.

Roll out when terrain avoidance is assured, begin a climb, and raise flaps.

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The Flight – Course Reversal

Another version

Assumes you have altitude to lose

I.e., you’ve given yourself an “out”

Pull to the horn and descend as required

Add power to reduce altitude lost
Idle if altitude is of no concern

It will keep you from possibly over speeding the airframe

People don’t normally operate in this regime

But it’s good for you and your flying skills

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The Flight – Forced Landings

Don’t choose a route which prevents a suitable forced-landing area
In a forced landing, approach at best glide, but touch down / impact at stall speed
Don’t leave the airplane without a compelling reason

Temporary evacuation may be necessary if a fire hazard exists

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The Flight – Forced Landings

Landing in trees? “Head toward the light”

Light green trees are more pliable, younger than dark green trees

Don’t land in water

Can flip upside down
Could be less visible
Easily become hypothermic

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The Flight – Forced Landings

Follow roads whenever possible
Avoid flying over open water
Plan trip along routes that include populated areas and well-known passes, or over valleys whenever possible
Swaths cut through trees are usually power lines

Best to avoid them

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The Flight – Forced Landings

Learn how to turn it on
It may not turn on automatically

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The Flight – The Route

1V6

KANK

KAEJ

KLXV

KASE

KGWS

KEGE

KFLY

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