BCS3 / A220-300

Idle Descent VPA Calculator

Table-based vertical path angle and top-of-descent estimate, with wind, ISA deviation and anticipated anti-ice corrections.

Simulation use only

Descent inputs

FT
Table range 10,000–41,000 ft
KG
Chart range 45,000–58,740 kg
KT
Positive = headwind · Negative = tailwind
°C
Positive = above ISA · Negative = below ISA
Anti-ice anticipatedApplies the chart correction of −0.20°

Approximate VPA at 55 t / 121,254 lb

M0.783.1°
M0.743.0°
290 KT3.5°
275 KT3.3°
250 KT3.0°
GREEN DOT2.5°
This lookup is for idle descent to sea level. The corrected distance is a geometric estimate using the corrected VPA; allow separately for route constraints, level-offs and deceleration. The chart's ±3%/4% distance rule is retained in the notes but is not automatically applied because its reference distance is not identified on the source image.
Set on FMS PERF – DES
3.05°
Exact chart valueFL320 · 52.0 t
Base table VPA3.05°
Table TOD to SL99.0 NM
Corrected TOD estimate99.0 NM
Total VPA correction+0.00°

Correction breakdown

Wind+0.00°
ISA deviation+0.00°
Anti-ice+0.00°
Calculation rules and interpolation
The base distance and VPA are bilinearly interpolated between the nearest cruise-altitude and landing-weight cells in the supplied chart. The source chart is indexed in kilograms; pound entries are converted internally.
  • Each 10 kt headwind adds 0.10°; each 10 kt tailwind subtracts 0.10°.
  • Each 10°C below ISA adds 0.10°; each 10°C above ISA subtracts 0.10°.
  • Anticipated anti-ice use subtracts 0.20°.
  • The corrected TOD preserves the chart's descent height and recalculates distance from the corrected VPA.
  • The chart states: each 0.1° below 3.0° = −3%, and each 0.1° above 3.0° = +4%; this remains reference-only because the image does not identify the percentage's distance baseline.