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 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 a complete review — and possible rework — of the flight plan in light of the current conditions and forecast. Don't forget to bring the various recommended items (below) with you on the day of your mountain checkout flight.

Reading and References (read before ground session)

Discussion Topics (for ground and flight sessions)

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 (rough 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 3.33 percent of its horsepower for every 1,000-foot increase in density altitude. So at a density altitude of 7,000 feet, 25 percent of engine power has vanished.

    • Minimum required Rate of Climb (ROC) performance is a function of pilot skill level, relevant experience, and conditions. But a good guideline is to require at least 400 FPM expected performance at the airport elevation. If the performance charts predict performance less than this number, in the expected conditions, then you should plan for another day, time, or location.

Cessna C172SP

Cessna C182T

Cirrus SR20

Cirrus SR22

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

    • 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 orthographic lift

    • Larger turning radius due to higher ground speed

    • 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 use the wrong units)

      • Even 1% is very noticeable, 4% 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:

      • 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 a lower climb gradient

        • 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

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

Emergency / Rescue Issues

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

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:

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 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%?).

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

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

    • Learn/use canyon turn to maneuver/escape in tight canyons.

    • 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.

    • Consider flap settings for takeoff and landings as appropriate for the situation

    • Make a reconnaissance pass of airport and runway before landing.

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

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