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)
- FAA Safety - Safety Enhancement Topic - Mountain Flying
- Tips on Mountain Flying FA-P-8740-60
- 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)
- Thunderstorms - AC 00-24C
- POH for your aircraft - Especially the chapters on performance (5) and Emergency Procedures (3)
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 3.5 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.
- Use POH and actual/predicted conditions to calculate expected performance
- Make sure to use recommended leaning - often lean above 3,000-5,000 feet
- 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 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
- 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)
- 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)
- (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
- Box/narrow canyons (L05 - Kern Valley)
- Cables and towers
- non-standard airports, patterns, and approaches
- Runway hazards
Emergency / Rescue Issues
- 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
- Communication/signalling is often your best bet for rescue, have multiple options available
- Bring emergency supplies
- First aid kit
- Food and water
- 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.)
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 (read Flying Magazine article on Hypoxia)
- Oxygen can be beneficial starting as low as 5-10 thousand feet
- Use may use a Pule Oximeter to monitor you blood oxygen saturation level
- FAR 91.211 Supplemental oxygen
- Required for flight crew over 12.500' if over 30 minutes
- Required for flight crew over 14,000'
- Must be provided to passengers above 15,000'
- Nasal cannula may be used up to 18.000'
- Regulations call for a mask over 18.000'
- 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
- 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:
- Defer to another day if winds are > 20-30 kts.
- 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.