Mountain Airport Density Altitude Planner
Plan hot-and-high operations: density altitude plus normally-aspirated power loss for mountain strips like Leadville, Telluride and Big Bear.
At Leadville on a 25 ยฐC afternoon, density altitude exceeds 13,000 ft and a normally-aspirated engine delivers barely two-thirds of its rated power โ before the propeller and wing penalties stack on top.
Formula
โ ๏ธ For flight planning and education only โ always verify against your aircraft's POH/AFM, official weather sources and certified instruments. Not for primary navigation or airworthiness decisions.
Plan hot-and-high operations: density altitude plus normally-aspirated power loss for mountain strips like Leadville, Telluride and Big Bear.
About Mountain Airport Density Altitude Planner
Mountain strips punish optimism. This planner is tuned for hot-and-high decision-making: it computes density altitude for a mountain airport and converts it into the number that actually matters โ the percentage of rated power your normally-aspirated engine can still produce. The default is Leadville, Colorado (9,934 ft), the highest public-use airport in the United States, on a deceptively pleasant 25 ยฐC afternoon.
How to use Mountain Airport Density Altitude Planner
- 1Enter โ sensible defaults are pre-filled so you see a worked result immediately.
- 2Read the live results: .
- 3Check the "With your numbers" line to see the formula DA = PA + 118.8 ร (OAT โ ISA); ฯ = (1 โ 6.876ร10โปโถ ยท DA)^4.256; Power โ ฯ ร 100 % substituted step by step.
- 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.
Why use Mountain Airport Density Altitude Planner?
- โInstant, free and private โ every calculation runs in your browser, nothing is uploaded
- โBuilt on the published formula DA = PA + 118.8 ร (OAT โ ISA); ฯ = (1 โ 6.876ร10โปโถ ยท DA)^4.256; Power โ ฯ ร 100 % with sources cited on the page
- โAt Leadville on a 25 ยฐC afternoon, density altitude exceeds 13,000 ft and a normally-aspirated engine delivers barely two-thirds of its rated power โ before the propeller and wing penalties stack on top.
- โSwitch units, tweak any input and watch every result update live
Frequently asked questions
Why show power loss instead of just density altitude?+
Because pilots feel power, not feet. A normally-aspirated engine's full-throttle power falls roughly in proportion to the density ratio ฯ, so a 13,000 ft density altitude means about 65% of sea-level power. Framing DA as lost horsepower makes the go/no-go conversation concrete.
What density altitude should stop me from departing?+
There's no single number โ it depends on aircraft, weight, runway and obstacles. A useful personal rule for normally-aspirated trainers: above 10,000 ft DA, treat any POH takeoff figure with deep suspicion, depart at reduced weight in the cool of the morning, and insist on a climb-gradient check against terrain, not just a takeoff-roll check.
Does leaning the mixture recover the lost power?+
Leaning recovers the power lost to an over-rich mixture, not the power lost to thin air. At high density altitude a full-rich mixture wastes some of the little oxygen available, so leaning for best power before takeoff (per POH) is essential โ but it only claws back a few percent, never the 30%+ the altitude took.
Are turbocharged engines immune at mountain airports?+
A turbocharger maintains sea-level manifold pressure up to its critical altitude, so engine power holds up well. But the propeller still bites thinner air and the wings still need higher true airspeed, so takeoff rolls remain longer and true-airspeed-based climb gradients shallower. The airframe never gets the altitude waiver the engine does.
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