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Calcimator

Mountain Flying Calculator

Density altitude, climb performance, and ridge clearance analysis for mountain flying operations.

Inputs

Results

Density altitude (ft)

11,100

Available climb (fpm)

87

Required climb (fpm)496
Can clear ridge (1=Yes)0
Min crossing alt (ft)12,500
Time to climb (min)57.5
Distance during climb (NM)85.6
Climb gradient (ft/NM)58
Pressure altitude (ft)7,500
Ridge Density Alt14,100
How to Use This Calculator
  1. Enter field elevation (ft), outside air temperature (°C), and altimeter setting (inHg).
  2. Set the ridge elevation (ft) to clear and distance to that ridge (NM).
  3. Enter your sea-level climb rate (fpm) from the POH at your gross weight.
  4. Review density altitude, available climb rate at altitude, required climb rate, and minimum crossing altitude.
  5. If your available climb does not exceed the required rate, depart earlier in the day or reduce weight.

How the result changes with Altimeter (inHg)

Altimeter (inHg)Density altitude (ft)Available climb (fpm)
2615,9610
2714,7210
3011,00193
319,761170

What each input means

Field elevation (ft)
Departure airport elevation.
Temperature (°C)
Outside air temperature at the departure airport.
Altimeter (inHg)
Current altimeter setting.
Ridge elevation (ft)
Elevation of the terrain/ridge to cross.
Distance to ridge (NM)
Horizontal distance from departure to the ridge.
Sea-level climb rate (fpm)
Rate of climb from POH at sea level, max gross.
Cruise TAS (kts)
Normal cruise true airspeed.
Headwind (kts, neg=tail)
Headwind component toward the ridge.
Ridge clearance (ft)
Desired clearance above the ridge (2,000 ft recommended).
Aircraft weight (lb)
Current takeoff weight.
Max gross weight (lb)
Maximum certificated gross weight.

What each result means

Density altitude (ft)
Effective altitude for engine/airfoil performance.
Available climb (fpm)
Estimated climb rate at current conditions.
Required climb (fpm)
Climb rate needed to clear the ridge from the current distance.
Can clear ridge (1=Yes)
1 if available climb exceeds required, 0 otherwise.
Min crossing alt (ft)
Ridge elevation + desired clearance.
Time to climb (min)
Minutes to reach crossing altitude.
Distance during climb (NM)
Horizontal distance covered while climbing.
Climb gradient (ft/NM)
Feet gained per nautical mile of travel.
Pressure altitude (ft)
Field elevation corrected for altimeter setting.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Field elevation (ft) = 7500, Temperature (°C) = 30, Altimeter (inHg) = 29.92, Ridge elevation (ft) = 10500 = 11 input(s) provided
  2. Calculate Density altitude
    Density altitude = pressureAltitude + 120 * tempDeviation
    11100 = 11100
  3. Calculate Available climb
    Available climb = seaLevelClimbFpm * daClimbFactor * min(1.2, weightFactor)
    87 = 87
  4. Calculate Required climb
    496 = 496
  5. Calculate Can clear ridge
    Can clear ridge
    0 = 0

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