At 9,000 feet, the 180-horsepower Lycoming engine in a Cessna 172 makes only about 130 horsepower. Thinner air at this altitude prolongs takeoff rolls, diminishes climb rates, and can add 10 to 15 knots or more to a trainer’s true airspeed on approach. Heat amplifies the effects of altitude, making Lake County Airport (LXV) in Leadville, Colorado, inaccessible to many aircraft by midday.
But in the mornings, Leadville is a popular training site to experience the dramatic effects of density altitude on aircraft performance. The airport sits at 9,934 feet in a high mountain valley between the fourteeners of the Mosquito and Sawatch ranges. A 6,400-foot runway welcomes high-altitude training programs and bucket-listers, and an FBO offers certificates to pilots for landing at North America’s highest public-use airport.
I claimed a certificate at Leadville during a mountain flying orientation flight that covered the effects of altitude and topography on aircraft performance, weather, and planning, factors Features Editor Alicia Herron describes this month in “Mountain Flying Basics,” (June 2025 Flight Training). Mountain flying instruction includes everything from what to wear and when to fly to leaning the mixture and avoiding downdrafts, and learning such lessons against the backdrop of the Rockies underscored the stakes. Towering peaks, inhospitable terrain, churning winds, and fickle weather in the West demand respect.A stable atmosphere and strong winds across terrain are the key ingredients for mountain waves.
Most of the time, however, I fly on the East Coast, where the mountains are less imposing and density altitude is less extreme. The tree-covered ridges of the Appalachians look like foothills compared to the Rockies, but mountain flying knowledge and skills are useful beyond the Mountain West.
On a trip from AOPA’s Maryland headquarters to the Sun ’n Fun Aerospace Expo in Florida, AOPA Editor at Large Dave Hirschman and I crossed a ridgeline in Virginia and the Cessna 152 struggled to hold altitude. I added power, then some more, then looked to my right to ask Hirschman: Is this what mountain waves feel like? With two adults and bags on board, the two-seater couldn’t hold altitude even with full power. We alerted air traffic control to the forthcoming altitude variations and rode the waves.
A stable atmosphere and strong winds across terrain are the key ingredients for mountain waves, which oscillate on the lee side of a ridge. Visualizing the airflow as water in a rocky stream helps explain why we bobbed like a leaf on the undulating wind—and why the up- and downdrafts subsided when we crossed to the windward side.
Mountain airports require extra planning because their runways may be short or obstructed, and pilots often can’t take sea-level performance for granted. I normally fly out of relatively unobstructed airports, but a planned flight to Cumberland Regional Airport (CBE) in Maryland this winter sent me to the chart supplement, instrument approach chart, and Google Maps looking up details of rapidly rising terrain 700 feet to the left of the approach to Runway 5. Even though 5,000 feet of pavement stretched out ahead of me, I made a steeper approach for terrain clearance and managed airspeeds throughout the pattern with short-field technique in mind to avoid overshooting the base-to-final turn.
Mountain flying in the East isn’t as dramatic as its Western counterpart, and I’m no hard-core mountain flier. But understanding density altitude, wind, and weather is important for any pilot, and America’s mountain range can still remind us of its power.
I recently took Herron, our West Coast staffer, on a flight to see Front Royal Airport (FRR), a picturesque field in Virginia’s Shenandoah Valley. I wondered if our ridges and valleys would seem blasé to a pilot like Herron, who earned her ratings among the mountains of the West. But as I lined up for takeoff on Runway 28 with Massanutten Mountain off the end, she assured me: “This counts!” FT
