Mountain Flying With A Flight Simulator 

While flying in mountainous terrain offers incredible views and amazing destinations, it also comes with many challenges for the pilot and the aircraft. We’re talking about one-way in  airports, high-density altitude, narrow-sloping runways, and fast-changing weather. Flying in mountainous terrain is one of those situations that many private pilots typically never fly in – The majority of pilots keep to flat terrain. Pilots are urged to have a minimum of 250 hours of flight time before even flying into the mountains. If you’re a person who lives near mountains or plans to make longer trips, it’s encouraged to enroll in mountain aviation courses to further that knowledge. 

A great way to increase your skill, be prepared and confident in safely flying in the mountains is with a home flight simulator.  In conjunction with real flying with your CFI, a simulator will help develop a pilot’s overall proficiency to master the art of mountain flying. Consider the following nine areas carefully before embarking on a flight in mountainous terrain.

1. Temperature Inversions
2. Effects of Density Altitude
3. Take Off & Climbing 
4. Ridge and Pass Crossing

Temperature Inversions

Typically, in the atmosphere, the temperature will decrease as you ascend in altitude. But in the case of a temperature inversion, the temperature will rise as you increase your altitude. This can occur when there is something causing the lower layer of air to become or stay cold (radiational cooling). For example, near an ocean or snow-covered ground. This also occurs in mountain valleys or large-scale valleys where there is not a lot of air mixing. For instance, in a valley, under the right circumstances, the colder, denser air will sink to the bottom of an air mass in the valley. Then the air above the ridge line will eventually be replaced with warmer air as the sun rises, thereby causing a temperature inversion due to the lack of air mixing at the bottom of the valley. 

In the event of any type of temperature inversion, there will be a reduction not only in visibility but also in the rate of climb, a lack of thrust, and a change in true airspeed due to the decrease in air density. Apart from some turbulence when passing through the different layers, it also creates a ‘dirty’ layer of air in your path, which is caused by pollutants being trapped in the cold air layer and unable to disperse higher up – Thus, impending your visibility while flying. 

Effects of High Density Altitude

Three variables determine air density – Pressure, Temperature, and Humidity. The definition of Density Altitude is simply pressure altitude corrected for nonstandard temperature. The International Standard Atmosphere (ISA) value is 15°C at sea level. With the standard adiabatic lapse rate being 2°C per 1,000ft of altitude change. So, what does all of that mean? A quick example, as we go up to 2,000ft MSL, the temperature on a standard day should be 11°C. If it is any higher than that, it is considered to be a higher Density Altitude. In other words, the airplane will “feel” as though it’s at a higher altitude than it is. High-density altitude will reduce your aircraft's power, thrust, and lift. Humidity will also alter an air mass’s density. As water vapor takes up the space that air would normally reside, resulting in less dense air, further decreasing an aircraft’s ability to create lift in that air mass. This results in a longer takeoff roll, a lower rate of climb, and a lowering of the aircraft's service ceiling. Because of the detrimental effects on aircraft performance, every pilot should exercise caution and adjust for the increased density altitude during takeoffs and landings. 

Since your takeoff and landing distances are increased, it’s helpfulx to practice these with a flight simulator. One way to know and practice your aircraft’s performance limits is to fly in the mountains on a flight simulator to see the effect. Make sure you’re proficient in maintaining your appropriate airspeeds, for example, Vx and Vy - Be familiar with your V speeds for when the situation arises. 

The key to understanding the differences in flying in high-density altitude is to practice in mountainous terrain, then quickly fly in flat land scenarios to see those differences – Something that is much easier (and cheaper) in a flight simulator than a real aircraft.

Take Off & Climbing 

As we’ve mentioned multiple times throughout this article, your take off will be affected the most when flying in the mountains due to high-density altitude. Expect a longer takeoff run and pay close attention to maintain the properly indicated airspeed. 

Taking off in Gusty wind conditions: Just as you were likely taught to increase your approach speed by one-half of the gust factor, the same is true for taking off. If you encounter gusting winds on your take off, take half of the gust factor and add it to Vr.

Taking off with a Tailwind: Backcountry airstrips in the mountains are commonly located near streams and rivers. You must bear in mind that while it is desirable to take off downstream and land upstream so that the terrain assists you in accelerating and decelerating, you must consider the wind. As discussed previously in the canyon tips, when the sun rises, it can cause the wind to move upstream (A Valley Breeze) and is generally clocked around 4-6 knots. So ask yourself this question, when landing upslope in the morning during a valley breeze, will you likely be experiencing a headwind or a tailwind? So do you want to land upslope or downslope?

This means when landing upslope as generally desired, the plane will be experiencing a tailwind, and in the evening (During a mountain breeze typically clocking around 10-12 knots), when landing downslope as typically desired, the airplane will also be experiencing a tailwind. So what do you do? The unfortunate not-so-easy answer is use your best judgment based on all of the factors, including wind speed, density altitude, the terrain in and around the airport, etc. However, there is a complicated answer to the complicated question: trying to determine the “Break-Even Wind Speed” explained in further detail in the Mountain Flying Bible: Revised by Sparky Imeson. If you’re serious about mountain flying, this book may very well save your life. The take-off chapter discusses how it calculates this break-even speed by taking into account the slope of the runway, wind speed, rotate speed, density altitude, and the aircraft's performance. So check it out if you’re interested in the math of it all.

Ridge and Pass Crossing 

You must cross at least one ridge or pass during most mountain flights. The cardinal rule is to cross a ridge or pass at least 1,000 feet above the ridge elevation and 2,000 feet if the winds indicate a downdraft or turbulence. It is recommended to do this at a 45° angle to the ridge, which allows you to turn away from the ridge quickly if there is any turbulence or downdraft. One of the best rules of thumb we’ve heard is if you have to cross some ridgelines, continue to climb until your altitude is above the ridge line, as opposed to climbing while en route to the ridge line. 

Here is a list of airports to practice on a home flight simulator that has high-density altitudes as well as major ridge crossings - 

• TEX - Telluride Regional
• Oliver Springs Inc Airport-TN08
• Monument Municipal Airport (FAA LID: 12S0
• Future Oak Ridge Airport
• Monument Municipal Airport-12S

Practicing Mountain Aviation With A Flight Sim

We’re all well aware that a flight simulator is extremely beneficial in staying proficient, establishing muscle memory, and giving you more confidence in flying. But one of the best reasons to use a flight simulator is to practice flying in conditions you are unfamiliar with and/or completely avoid. While many of us seldom fly in this kind of terrain, it’s imperative to practice because the effects on your aircraft are so different (and dangerous) compared to flat terrain. 

Here are three areas a pilot should practice to perfection on a flight simulator to operate in the mountains:

1. Knowledge of stalls and what causes the stall speed to increase
2. Engine out procedures 
3. Airspeed control