Aircraft performance and weight & balance reference
Weight, CG, pressure altitude, temperature, wind, runway condition and configuration affect aircraft performance. Identify the required inputs, then use the applicable POH/AFM chart and its corrections. Keep generic calculations separate from aircraft-specific performance.
Start with the aircraft and loading condition
Confirm the aircraft identity, current empty-weight data, equipment configuration, occupant and baggage stations, and fuel units. Calculate loaded weight and center of gravity with the applicable approved records; verify both against the correct loading envelope. A mathematically correct moment calculation can still be wrong if it uses stale arms, an incorrect fuel weight, or a different aircraft's limits. See the weight-and-balance guide, loading-envelope guide, and weight-and-balance workspace.
Atmosphere changes the chart inputs
Pressure altitude and outside-air temperature help describe the atmosphere used in performance calculations. Density altitude expresses the density effect in altitude terms, but it does not replace chart-specific pressure, temperature, wind, or runway inputs. A high density altitude generally reduces engine, propeller, and wing performance. Review pressure altitude, ISA temperature, and density altitude, then use the airplane's current performance charts.
Climb: connect airspeed, time, and distance
Vx is best angle of climb: greatest altitude gain for horizontal distance. Vy is best rate: greatest altitude gain per unit time. A climb gradient expressed in feet per nautical mile is also different from vertical speed in feet per minute. For a check, ft/NM = FPM × 60 ÷ groundspeed in knots. At 500 fpm and 90 kt groundspeed, the result is about 333 ft/NM. The example checks units and arithmetic; obstacle performance must still come from the applicable approved data and procedure.
Continue with Vx versus Vy, climb rate versus gradient, and obstacle climb-gradient math.
Turns, loading, and stall margin
In an ideal coordinated, level turn, load factor rises as bank increases: n = 1 ÷ cos(bank angle). At 60° of bank, the idealized load factor is 2. Stall speed in the same configuration varies with the square root of load factor, so the idealized ratio is about √2, or 1.41 times the one-g stall speed. This explains why a steep level turn raises stall speed; it does not provide an aircraft's approved maneuvering speed or a safe maneuver limit. See load factor and accelerated stalls, turn radius and rate, and maneuvering speed at weight.
Glide and runway performance need their own assumptions
A glide ratio describes still-air distance relative to height under stated conditions; wind changes distance over the ground. Runway contamination can reduce braking and directional control, and the tire-pressure hydroplaning estimate is not a landing-distance calculation. Use current runway reports and approved landing-performance procedures. Review glide-range assumptions and hydroplaning types and limits.
Read the chart inputs and corrections
- Use current approved data for the actual aircraft and configuration.
- Identify chart units, weight, pressure altitude, temperature, wind, runway, and technique assumptions.
- Interpolate only when and how the chart or manual permits; do not extrapolate beyond its range.
- Apply required corrections and margins exactly as specified, then record the source and result.
- Recheck the selected weight and CG limits separately from takeoff or landing performance.
PilotDesk's POH Chart Studio can help organize a study calculation. It is not approved aircraft data.
The FAA Airplane Flying Handbook and the airplane's current AFM/POH provide primary references for performance concepts and aircraft-specific procedures.