by Bob Worthington
Published in Midwest Flyer – February/March 2020 issue
This time of the year, my wife and I – relaxing in front of our cozy fireplace, a U.S. map on our coffee table – would plan fun places to visit in better weather beginning in a couple of months. Our map had concentric circles drawn with the center our airport, and each circle representing two hours flying time. We live at the southern end of the Rocky Mountains in Las Cruces, New Mexico.
I am inviting Midwest Flyer Magazine readers to consider flying into my mountains. Many of you already have mountain flying experience. On the other hand, others may not, but might hanker for an adventure flying into and landing at some high-altitude airport in the mountains just west of you.
The Midwest is mostly flat, without any real height. So, flying into the mountains can be exciting, challenging, and certainly adds to the skills of any pilot. Without the proper training, however, mountain flying can be risky.
Are you interested in learning mountain flying without being in the mountains? Is it possible to learn about mountain flying without leaving the Midwest? The answer is yes! Heres how.
When I was a new pilot, my Army assignment was San Antonio, Texas, elevation 800 feet (MSL), give or take a dozen feet; obviously, not in the mountains. Growing up in rural Connecticut, hunting, shooting, fishing and camping captured my full-time attention. My favorite fishing was for Brook Trout, but Texas is not a state with trout streams, so I had to go further west to go fishing.
New Mexico has both deserts and mountains. And the mountains are full of excellent trout streams. I became a pilot, so I would be able to travel efficiently, quickly, and without hassle. Therefore, the mountains of New Mexico contained the closest places for trout fishing. But flying into and landing in the mountains, even I realized, could be very dangerous without the appropriate training. So, I asked various flight schools where I could find a Certified Flight Instructor (CFI) with mountain flying experience. Very quickly, I located one, explained what I wanted to do, and the instructor said he could do that.
First, my instructor provided plenty of pamphlets and articles from both the Aircraft Owners and Pilots Association (AOPA) and the Federal Aviation Administration (FAA) on mountain flying. Today, one could simply use the Internet to get tons of information on the subject.
After I studied all the reading materials, my instructor and I met where he began to teach the basics of mountain flying. Next, we flew my plane, practicing mountain flying techniques. Now is the time to ask how does one practice landing and departing 7,000-ft. high runways when the highest ground is at 800 feet? The answer is simple.
Your experienced CFI has you landing and departing on a local dirt strip using reduced power to simulate performance at higher elevations. My CFI would set up situations, such that I would have to land because a go-around would smash me right into a mountain. We would practice departures where the reduced power would hamper climb, so I would have to calculate my departure flight path to ensure that a long and slow climb wouldn’t impact any terrain or trees. We did this for several days until I became very proficient handling my plane at reduced power settings.
Next, he had sectional charts with mountains where he would select an airport and provide the temperature at the airport. I would get its elevation and then use density altitude charts to calculate if I could land there and if the runway was long enough to take off.
Density altitude (DA) is a key term in safe mountain flying. Essentially, the higher the airport (elevation) and the higher the temperature, the less dense (thinner) the air is. DA is a calculated higher elevation (due to temperature and actual elevation) that an airplane will perform at.
Consider this. Today’s computerized cars have digital air pressure readouts for each tire. One cool evening you notice you have a low tire, so you fill it up to 33 psi. The next morning, you have a 10-mile drive to your job. As you pull into parking, you check the tire pressure and it is now 37 psi. What happened? You put in 33 psi, but now it is 4 lbs over. Why?
Hot air expands. Driving fast for 20 minutes or so heated the tire which heated the air in the tire, and it expanded. In the tire, the space for the air remained unchanged, so the air pressure just increased. In the sky, though, there is no contained space, so when warm air expands, it gets thinner.
So how does DA impact aircraft performance? With less dense air, the horsepower of a normally aspirated engine is reduced. With less power, the climb is slower and longer (simply meaning the flight path would be much longer and the takeoff roll would require longer runway distance). And the efficiency of the propeller is less effective. So, in mountain flying, both altitude (elevation) and heat can severely diminish the performance of an aircraft.
As an example, an airport at a 7,000-ft. elevation at 90 degrees has a DA of 10,500 feet. If a normally aspirated (i.e. non-turbo) aircraft has a service ceiling of 13,000 feet, the aircraft probably couldn’t climb over 200 feet and it would take a very long runway to even get airborne.
Here is a real example of how this works.
A few years ago, on a summer afternoon, two couples boarded their normally aspirated complex aircraft in east Texas, departing their 600-ft. elevation airport. Their destination was a mountain resort area in New Mexico, to escape the heat and humidity of east Texas. They arrived at the 6,814-ft. elevation airport just before dusk, in the cool of the evening, and requested the FBO to fill their tanks. For the next day and a half, they enjoyed golf and gambling, horseracing and shopping.
At noon on Sunday, they loaded their plane with their luggage, golf bags, and the goodies from shopping. The weather briefing promised clear skies and a 15-knot tailwind. A perfect flight to end a perfect weekend. Unfortunately, the pilot was not aware of density altitude and his aircraft was at gross weight with four adults, baggage, plus full fuel. The temperature at the airport was 85 degrees, placing the DA around 10,000 feet. Being in the mountains, the area surrounding the airport contained many tall trees.
The pilot rolled down the runway, barely attaining ground effect before the end of the runway. Out of ground effect, the climb gradient was virtually zero, so the plane hit some trees, crashed and caught fire. There were no survivors.
The above scenario is not described to scare anyone from flying in the mountains because it could have been easily avoided, if the pilot understood DA.
Prior to the flight, the pilot could have obtained temperature forecasts and calculated the DA and then computed takeoff performances at different aircraft weights. The golf bags could have been left at home (golf courses rent them) and they could have taken on only enough fuel to get out of the mountains, landing at a lower elevation for more fuel. Or the pilot could have departed early in the cool of the morning. Departing at night is not recommended for flying in the mountains. The point is, understand mountain flying BEFORE flying in the mountains!
Training with a mountain savvy CFI with actual experience, reading books and articles on mountain flying, and of course the Internet offers hours of courses, videos, and tutorials on mountain flying. Even without leaving the Midwest, a pilot can become educated and safe for mountain flying and avoid the accident of the east Texas pilot.
The New Mexico Pilots Association (nmpilots.org) hosts a weekend mountain flying clinic each fall with 8 hours of ground school and mountain flying.
Here are some simple tips for flying in the mountains and using high-altitude airports in the summer:
1. Fly only in the morning when the weather is cooler and more stable. Afternoons often see rain showers and more wind.
2. Do not fly in mountains, either on instruments (IFR) or at night. Excellent visibility greatly reduces risks.
3. Understand DA. Have access to DA charts so you can calculate your aircraft’s performance to ensure safe landings and departures before flying.
4. Carry supplemental oxygen to avoid becoming hypoxic.
5. Understand how winds act in the mountains and how they can affect flying, landing and departing.
6. Avoid flying if there are rain showers, fog, or low clouds around the mountains and valleys.
7. Understand terrain navigation. GPS is excellent, but good mountain pilots also depend on terrain-type charts or maps to know exactly where they are, especially relative to where they want to go.
8. Understand that in many mountain areas, there are natural saddles, passes, or valleys that afford easy means to cross mountains.
9. It is handy to talk to a pilot familiar with where you want to go to get his/her personal advice on things to do or avoid. Calling a local FBO or flight school where you want to go should put you in touch with a local expert.
10. Lastly, for your first trip into a high-altitude airport, select a location around 5,000 to 6,000 feet elevation with long, hard surface runways, and gentle, easy approaches. When there, take the time to hire a mountain CFI and spend a day flying into the mountains.
I have spent considerable time flying in the mountains and landing on out-of-the way/ rough dirt strips, high up in the mountains. While challenging a pilot’s skills, if properly trained, and obeying all the common-sense rules and laws of mountain flying and into high-altitude airports, it can be a safe and fun-filled endeavor.
I would use a small aircraft to get into short dirt strips at 6,000 to 7,000-ft. elevations. I would land with 1/3 to 1/2 fuel (because an airport at a much lower elevation would be 30-45 minutes away) late afternoon with lower temperatures, thus a lower DA. Also, later in the day, the winds would have lessened.
Usually, I would be flying over lower terrain and my trip into the mountains would only be the last 20 or so minutes of flight. After securing my aircraft, I would eat a cold meal and go to sleep. Arising the next morning, I would eat, slip on my backpack, grab my fishing gear, and head up the mountain to a clear stream, full of Brook Trout for excellent fishing (with no one else within 10 or more miles). The last day of fishing I would hike back down to the plane, eat, go to sleep and arise at dawn, then pack up and load the plane, preflight and depart when the air is cool and calm, then head for the nearest airport at a lower elevation to refuel and return home.
Get out a U.S. map and your airport directory. Look for exciting places on the eastern slopes of the Rockies at 5,000 to 6,000-ft. levels. Check out their airports (elevations, length of runways – multiple runways are best for winds – and services available). Use the Internet to learn about the type and availability of food, lodging, and all the fun things to do.
Suggestions for fun places to visit that have all the above services and tourist attractions are Santa Fe, New Mexico at 6,348 feet; Colorado Springs, Colorado at 6,187 feet; Casper, Wyoming at 5,350 feet; and Cheyenne, Wyoming at 6,159 feet. Now plan your summer trip.
EDITOR’S NOTE: Pilot, Viet Nam veteran and former university professor, Bob Worthington of Las Cruces, New Mexico, is the author of “Under Fire with ARVN Infantry” (https://mcfarlandbooks.com/product/Under-Fire-with-ARVN-Infantry/), and producer of the 2019 film “Combat Advisor in Vietnam” (www.borderlandsmedia.com). Facebook: Bob Worthington Writer (www.BobWorthingtonWriter.com).
DISCLAIMER: The information contained in this column is the expressed opinion of the author only, and readers are advised to seek the advice of their personal flight instructor and others, and refer to the Federal Aviation Regulations, FAA Aeronautical Information Manual and instructional materials before attempting any procedures discussed herein