Mountain Checkout

Mountain Checkout / Mountain Flying

Due to the unique set of challenges encountered, it's a good idea to do a mountain checkout before flying as PIC in the mountains, deserts, and other remote or challenging areas. WVFC requires a Mountain Checkout before members are allowed to take club aircraft into the mountains.

The outline below serves as a framework for a mountain checkout. The ground portion usually take approximately 2-4 hours, depending on your background and experience, and your success at completing the prescribed reading ahead of time. The flight portion typically takes all day, and includes approximately 5 hours of flight time. We usually get lunch at someplace interesting along the way.

It is best to do the ground portion in a separate session days in advance of the flight portion. You should schedule 2.5-4 hours for the ground session (depending on your experience), and a full day (0800-1900) for the flight portion. The day of the flight usually starts with a thorough flight briefing and review of the flight plan — and possible rework — in light of the current conditions and forecast.

On the day of your mountain checkout flight, don't forget to bring the various recommended items (below) with you. And when you preflight your aircraft, be mindful of aircraft weight & balance and do not automatically "top off the tanks for a long flight." In many cases, we will want no more fuel than "to the tabs" before departure (yet within safety margins, including appropriate reserves). Our goal is to arrive in the mountains at or below 90% of our maximum gross weight for the aircraft.

Reading and references (read/review at least some of these items before ground session)

• • FAA Safety - Safety Enhancement Topic - Mountain Flying

  • Tips on Mountain Flying FA-P-8740-60 - Although this document is dated WRT presentation (it's very old school black-and-white, text based) the content is really quite good.

  • AIM - Mountain Flying 7-5-6

  • High-Altitude Flying: What You Need to Know -- Learn the symptoms and dangers of hypoxia and how to prevent it (from Flying Magazine)

  • PHAK Chapter 11 - Aircraft Performance

  • Understanding Density Altitude - go beyond the textbook definition (by Mike Collins, AOPA)

  • Mountain Flying by the AOPA Air Safety Foundation

  • Thunderstorms - AC 00-24C

  • AOPA Mountain Flying - Online learning safety spotlight training course

  • POH for your aircraft - Especially the chapters on performance (5) and Emergency Procedures (3)

  • Note: Some additional references (such as relevant videos) are included in-line, below. But these are more supplemental rather than fundamental, and are therefore not enumerated here. 

Discussion Topics

At what altitude (or density altitude) does Mountain Flying begin?

• 2000' ?

• 3000' ?

• 5000' ?

• And is that MSL or AGL?

What is Mountain Flying?

• Mountain flying does not always involve mountainous terrain and high density altitudes

• Mountain flying is basically any flying where the pilot must deal with conditions or situations that are more demanding than "basic flying."

• Mountain flying often demands experience, research, planning, visualization, proficiency, "safety gates/limits" and "what if" planning

• NB: Briefing the Chart Supplement, sectional, and other relevant references before departure is a good place to start. But sometimes it is still not obvious that a particular airport has mountain flying challenges. Sometimes a bit of reading between the lines will help. When the chart supplement uses any of these words or phrases it may hint at terrain, obstacles, or other issues that may require mountain flying skills: closed, prohibited, mountain flying, not visible, not advised, extreme, only, terrain, one way, downdrafts, winds, etc.

Conditions or situations that call for Mountain Flying

• Performance - high density altitude, steep approaches, steep departures, strong downdrafts, ...

• Winds - greater than ~20 knots, up/down drafts, LLWS, extremely variable winds, leewards side turbulence/rotors, ...

• Visibility - limited by terrain, obstacles, smoke, glare, reflections, ...

• Terrain / Obstacles - terrain, trees, buildings, towers, cables, windmills, ...

• Non-standard - pattern, approach, departure, runways (slopped, one-way, humped, dipped, contamination, wildlife)

• Human factors - hypoxia, dehydration, fatigue, headaches, visual illusions, ...

• Limited communications due to terrain or distance

• Limited landing and route options

• Increased risk associated with off-field landings and subsequent survival and rescue

Some examples of mountain flying airports (but there are many, many more)

(I used the 7 Aug 2025 Southwest Chart Supplement for some of the information in this section.)

• Mammoth Lakes (MMH) @ 7135'

• South Lake Tahoe (TVL) @ 6268'

• Truckee (TRK) @ 5904'

• Alpine County (M45) @ 5872' ... Sectional

• Sierraville (O79) @ 4990'

• Weaverville Lonnie Pool Field (O54) @ 2350'

• Happy Camp (36S) @ 1209' ... NOTAM ... Sectional ... Video of approach and landing 3/8/2020

• Ocean Ridge (E55) @ 934' ... Sectional

• Andy Mc Beth (S51) @ 42'

• Death Valley Furnace Creek (L06) @ -210'

A note about Day, Night, VFR, IFR

• Mountain flying is generally flown Day VFR.

• Neither IFR nor night flight are particularly compatible with mountain flying. Both IFR and night flying are generally strongly discouraged in the mountains. (Turboprops and jets are possible exceptions, and then only to arrive/depart via safe corridors and procedures.)

• Night and IMC conditions obscure most visual cues, making terrain and obstacle clearance difficult if not impossible, especially in strong up/down draft conditions.

Aircraft Performance Issues

• • The trifecta of performance hits (due to thinner air as density altitude increases):

    • Thinner air ⇒ less power from engine (unless turbocharged or turbine)

    • Thinner air, less power ⇒ less thrust from prop

    • Thinner air, less power, less thrust ⇒ less lift from the wings

  • Climb rate reduced

  • Same indicated airspeed but higher ground speed for both takeoff and landing

  • Higher ground speed but with lower performance ⇒ greatly increased takeoff and landing distances

  • Density altitude - In California and the southwest, we tend not to think too much about the impact of high humidity on density altitude. But high humidity does raise the density altitude. A rule of thumb to use to calculate the impact of high humidity is to double the dew point temperature and add a zero to approximate the increase in density altitude in feet.

  • Density altitude - A rule of thumb is to add 120 feet per 1 °C over standard

  • Density altitude - Horsepower rule of thumb: A normally aspirated aircraft engine will lose approximately 3% of its horsepower for every 1,000-foot increase in density altitude. So at a density altitude of 7,000 feet, over 21% of engine power has vanished.

  • Aircraft Horsepower - Unless the pilot has a great deal of mountain flying experience, 160 HP should be considered the minimum power for mountain flying. Additionally, 60 HP per person should also be considered minimum. Note that these are minimums; in many cases greater horsepower is highly recommended, especially for those not significantly experienced in mountain flying.

  • Aircraft Weight - It is highly recommended that you limit your aircraft's weight to no more than 90% of it's maximum gross weight.  This reduction in weight will noticeably improve aircraft performance. Further weight reduction, when reasonably possible, will further improve aircraft performance. 

  • Reduced Fuel - One way to achieve a lower aircraft weight for your mountain flying (see above) is to limit your fuel to only the fuel needed, plus appropriate reserves. When able, plan on refueling at a lower altitude airport after leaving the mountain flying area rather than refueling in the mountains. If you need to add fuel while in the mountains, be judicious about the amount of fuel added.

  • The minimum required Rate of Climb (ROC) performance is a function of pilot skill level, the aircraft, and conditions. But a good guideline is to require at least 400 FPM expected performance at the airport's density altitude elevation.  A more conservative minimum of 500 FPM is recommended for pilots with minimal mountain flying experience (less than 6 flights in appropriately challenging mountainous environments). If the performance charts and calculations predict performance less than your minimum ROC then you should plan for another day, time, or location.

• • Use POH and actual/predicted conditions to calculate expected performance

    • Cessna C172SP Rate of Climb performance chart

    • Cessna C182T Rate of Climb performance chart

    • Cirrus SR20 Avidyne Rate of Climb performance chart

    • Cirrus SR22 Perspective Rate of Climb performance chart

  • From the above data, you should note that the C182 has approximately 150' better ROC performance at any given altitude than the C172. This performance improvement translates to about 3,000'-4,000' feet of additional usable altitude (to meet the same minimum required ROC performance).

  • Also note that the C172SP has better climb gradient performance than the Cirrus SR20. The SR20 is not a good match for the mountains.

  • Make sure to use recommended leaning - often lean above 3,000-5,000 feet (for the C182T use the fuel flow placard per the POH)

  • Abort takeoff if unable to reach 70% of Vr by midpoint of runway

  • W&B / DA / fuel / performance

  • Spiral up if/as needed to gain altitude (plan for extra flight time)

  • Leverage orographic lift

  • Larger turning radius due to higher ground speed - Higher true airspeeds result in larger radius turns (the increase in turing radius depends on if you are holding the rate of turn (directly proportional), or angle of bank (proportional to the square of the airspeed) constant for the comparison). Either way, it takes more distance to make a turn at a higher TAS than at a lower TAS, so be careful when turning at the the higher true airspeeds in the mountains.

  • Adjust mixture for maximum power during run-up/pre-takeoff power check

  • Consider runway slope

    • Given in at least 4 different forms: degrees, percentage, gradient, ratio (be careful not to confuse your units)

    • Note: For small angles (≤ 10°) each 1.0° = 1.75%

      • Simple percent to degree conversion: 1% = 0.6°, 2% = 1.1°, 3% = 1.7°, 4% = 2.3°, 5% = 2.9°, 6% = 3.4°, 7% = 4.0°

      • Simple degree to percent conversion: 1.0° = 1.75%, 2.0° = 3.5%, 3.0° = 5.25%, 4.0° = 7%

    • Even 1% (0.6°) is very noticeable, 4.1% (2.3°) is huge! (See O54 - Lonnie Pool Field at Weaverville, CA)

    • Consider both slope and winds for both takeoff and landing

    • Consider takeoff/departure before landing, especially at one-way in / one-way out airports

  • Flaps - alternate flap settings should be considered for both takeoff and landing:

    • From the PHAK, Chapter 11, Aircraft Performance:

Climb Performance Factors

Since weight, altitude and configuration changes affect excess thrust and power, they also affect climb performance. Climb performance is directly dependent upon the ability to produce either excess thrust or excess power. Earlier in the book it was shown that an increase in weight, an increase in altitude, lowering the landing gear, or lowering the flaps all decrease both excess thrust and excess power for all aircraft. Therefore, maximum AOC and maximum ROC performance decreases under any of these conditions.

• • • Takeoff

      • Takeoff flaps offer more lift, but they also present more drag

      • In a high density altitude environment this additional drag saps the already limited excess power available

      • Takeoff flaps can result in a shorter takeoff roll, but at the expense of wasted energy (KE + PE). Use minimum takeoff flaps, when able

      • Consider runway length available  vs expected climb performance

      • Consider a no flap takeoff if sufficient runway length is available

      • If you do use takeoff flaps retract them as soon as safe and practical to minimize drag and maximize performance

      • Make sure to use speeds appropriate for the chosen flap configuration

    • Landing

      • The use of full flaps can help reduce approach and landing speed and increase drag, thereby reducing landing runway requirements

      • But the use of full flaps reduces the excess power available (due to the significant drag) to overcome downdrafts or LLWS

      • Consider using full (or nearly full) flaps when landing on a short runway, as long as downdrafts and LLWS are not expected

      • Consider using only partial flaps to reduce drag and leave more excess power available to overcome downdrafts or LLWS, if sufficient runway is available

      • Consider an aiming point 1/3 the way down the runway if landing in the presence of downdrafts or LLWS, if sufficient runway is available

      • Make sure to use speeds appropriate for the chosen flap configuration (and appropriate corrections for gusting winds and LLWS)

Winds

• • Turbulence OK if < 20-30 kts, moderate if > 20-30 kts

  • Mountain wave if > 20-30 kts (can be indicated by a series of standing lenticular clouds) (rare photo of a mountain wave visible due to smoke)

  • Rotors / extreme turbulence

  • Up/down drafts (visualize and exploit updrafts, avoid downdrafts)

  • Venturi effect through passes and narrows

  •  Gusts & LLWS (Low Level Wind Shear) (TRK - Truckee, runway 20 in particular)

Dealing with downdrafts

Downdrafts are one of the more significant hazards in mountain flying. Here are some key thoughts about dealing with downdrafts and are in the context of "whenever reasonably possible:"

• Visualize airflow and avoid downdrafts

• One way to avoid a downdraft is to climb outside of the (main) downdraft. For example, circle above Truckee (*) to 10,500' or higher before proceeding over the highway 80 area to the West. (* Usually in the area of Prosser Creek Reservoir, leveraging the nearby lower hills to exploit updrafts.)

• If you can't avoid a downdraft, at least minimize your time in the downdraft. You can do this by controlling your route, or increasing your speed, or both

• Use minimal flaps - this maximizes the amount of engine power that can go into countering the downdraft (vs fighting the flaps)

• Avoid getting too slow - Vx and even Vy are often too slow when flying in the mountains. Speed is energy, and can be tapped if needed. A higher speed also provides a better view, better control authority, and better protection from a stall. A good speed is usually between Vy and Va, although the short approach and landing speed will often be closer to 1.3 Vs1 (depends on flap setting and other issues).

• If you expect that you might get into a downdraft situation, develop a plan before entering the downdraft area. Eg: "If we encounter a significant downdraft we will maneuver to this area and ..."

Weather

• • (See winds, above)

  • Can obscure mountains and obstacles

  • Can change rapidly

  • Thunderstorms are common in the afternoons

  • Maintain a minimum of 20 miles from thunderstorms (greater distance is better)

  • Poor visibility - smoke/fog can settle into a valley/canyon

Additional Hazards

• • Box/narrow canyons (L05 - Kern Valley)

  • Cables and towers ... cable depicted on sectional

  • non-standard airports, patterns, and approaches

    • One way in, one way out, commit to landing

    • Blind turns and approaches (O79 - Sierraville), Andy Mc Beth (S51)

    • Table-top runways and other illusions (E36 - Georgetown)

    • Irregular terrain and shifting winds (M45 - Alpine County)

  • Runway hazards

    • Animals on runway (moose, deer, elk, bear, etc.) (O86 - Trinity Center)

    • Vehicles, debris, etc. on runway (KBLU - Blue Canyon)

    • Snow on runway - may be closed in winter (KBLU - Blue Canyon)

Emergency / Rescue Issues

• • Basic Survival Training by the FAA Civil Aerospace Medical Institute (CAMI), Course Manual

  • 🎥 FAA Aircrew Survival Videos

  • Airports and fuel stops can be sparse, plan accordingly

  • Few good emergency landing options

  • Tell others of your plans

  • Flight plan / flight following

  • You may be injured or on your own for a long time

  • If remote, stay with or near aircraft if able

  • Survival Kit / Emergency Gear

    • 🎥 FAA Survival Kit Video

    • Emergency equipment location and operation safety card by AOPA

    • Communication/signalling is often your best bet for rescue, have multiple options available

      • 🎥 FAA Survival Signalling Video

      • Aviation handheld radio (121.5/guard for overflying aircraft even in canyons)

      • ELT (Emergency Locator Beacon)

      • Cell phone (TXT, messaging, email, voice mail - use them all)

      • Tablet with cell service (same options as cell phone)

      • PLB (Personal Locator Beacon)

      • SAT phone

      • Signaling mirror

      • Distress Flag

      • Strobe lights (aka "Electric flares")

      • Signal flares - pyrotechnic and/or smoke, may be difficult to find / purchase / maintain, See AC 91-58A for more details

      • Fire starter and kindling - to create smoke for signaling. See "emergency supplies", below

    • Bring emergency supplies

      • First aid kit

      • Food and water

      • Fire starter and kindling - How to build a campfire by NPR

      • Communications / signaling devices (see list above)

      • Extra power for electronic devices (cell phone, tablet)

      • Warm clothing and good shoes

      • Knife / rifle (Canada, Alaska)

      • Repair kit (duct tape, pliers, safety wire, etc.)

    • See special equipment requirements for Alaska - Official list from the Alaska DOT

Poor Communication Issues

• • Aviation COM and VOR NAV is based on VHF line-of-sight communications

  • COM radios may not work

  • NAV radios (including GPS!) may not work

  • Cell phones may not work

  • Close your flight plan / terminate flight following while still in COM range

  • Climb if/as needed for COM/NAV

  • Bring paper (or pre-downloaded) charts just in case

Altitude and Physiology

• • Oxygen - see my standalone oxygen lesson

  • AC 61-107B Change 1 - Aircraft Operations at Altitudes Above 25,000 Feet Mean Sea Level or Mach Numbers Greater Than .75  - Excellent comprehensive document, including: Time of Useful Consciousness table, medical physiology, types of Hypoxia, physics gas laws, high altitude flight, etc.

  • Altitude chamber training offered by the FAA Civil Aerospace Medical Institute (CAMI)

  • Introduction to Aviation Physiology by FAA Civil Aerospace Medical Institute (CAMI)

  • 🎥 FAA Physiology of Flight Videos

  • Stay Hydrated

    • Bring water and drink as appropriate to stay sufficiently hydrated

  • Visual illusions due to:

    • sloping or unusual terrain (PVF - Placerville)

    • narrow or ill-defined runways

    • tall trees

    • reflections

    • higher ground speeds

  • Beware of fatigue - mountain flying is very demanding

Pre-flight briefing for each airport of intended use

For each airport of intended use (including possible alternates) read all available information, including chart supplement entry, ForeFlight comments and remarks, airport-specific web pages (often related to the local municipality), etc. You goal is to learn of any hazards, limitations, conventions, recommendations, reporting points, contact information, etc. relevant to each specific airport. In particular, be alert for:

• • runway slope/gradient (uphill, downhill, humped, or dipped runways) (M45 - Alpine County)

  • one-way in, one-way out situations (TVL - South Lake Tahoe, 1O6 - Dunsmuir)

  • common wind patterns

  • local hazards

Recommendations

• • Defer to another day if winds are > 20-30 kts.

  • Remember to bring your mountain go bag (emergency kit)

  • Remember to bring emergency clothing, food, water, etc.

  • Give thunderstorms a wide berth - usually at least 20 miles.

  • Fly at least 2,000' above nearby peaks when flying over mountains.

  • Cross ridgelines at a 45° angle to improve escape options when flying near the peaks.

  • Lean the engine to maximize power at altitude (non-turbocharged engines).

  • Compute density altitude - DA adds approximately 120' for every 1 °C over standard.

  • Consult the performance section of your POH to verify performance under expected conditions. Determine climb performance and runway requirements for takeoff and landing.

  • Allow an additional margin of safety to account for sub-optimal performance of aircraft, pilot, winds, down-drafts, etc. (+20-50%?).

  • Be particularly careful of any airport where the runway length is less than the airport altitude (I treat this as a BRIGHT ORANGE FLAG)

  • Limit aircraft weight to 90% or less of MGW while operating in the mountains.

  • Do not "top off fuel" unless necessary. Refuel (as needed) when out of the mountains.

  • Abort takeoff if unable to reach 70% of Vr by midway point of runway.

  • Review your POH and determine/calculate Vx and Vy for your expected altitude and weight.

  • Adjust airport pattern to avoid/compensate for terrain, box canyons, downdrafts, etc.

  • Learn/use canyon turn to maneuver/escape in tight canyons, and remember that your turning radius increases as your airspeed increases

  • Always have a plan just in case you don't achieve the expected performance. (Eg, "On takeoff we're going to veer to the left around that hill if we don't achieve enough climb rate to climb over it.")

  • Learn/master short field landings and takeoffs - stay on glide, on spot (aim point), and on target for landing airspeed

  • Consider flap settings for takeoff and landings as appropriate for the situation, increase power available (for sink management / go-around) by using less than full flaps for landing (as long as the runway is long enough)

  • Make a reconnaissance pass of airport and runway before landing if/as appropriate

  • Departure often takes more runway than landing - check the numbers before landing.

  • Visualize the winds and airflow - when able, exploit updrafts and avoid downdrafts.