geoprimsField-grade geospatial math

Performance table lookup

Reads a POH performance table of one, two, or three variables, like takeoff distance by altitude, temperature, and weight, between its listed values, refuses to guess beyond them, and applies corrections as labeled steps.

Planning and education aid. Not for primary navigation. Full disclaimer

Experimental: not yet fully verified. How results are checked

1,336.5

The table gives 1,485; with the corrections, 1,336.5.

Cells used
First variableSecond variableValueWeight
20002013250.2500
40002015400.2500
20003014200.2500
40003016550.2500
Steps
StepValue
bilinear interpolation of the table1485
10 kt headwind (-10%)1336.5
From the table
Provenance
Computed by
aviation.loading.table-interpolate 1.0.0, core 0.1.0
Model
Linear interpolation along each variable between the listed values that bracket the query: 2 cells for one variable, 4 (bilinear) for two, 8 (trilinear) for three, each weighted by the product of its distances. No extrapolation. Corrections apply in order: percent (× (1 + p/100)), add, or multiply (PHAK, aircraft performance)
Accuracy
Exact interpolation of the table as entered; real performance between table rows is not linear, and the table is only as good as the book it came from
Notes
1 shown with the answer
Cites
Federal Aviation Administration, Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25C

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How we got thisFormula, worked example, sources, and proof

Model: Linear interpolation along each variable between the listed values that bracket the query: 2 cells for one variable, 4 (bilinear) for two, 8 (trilinear) for three, each weighted by the product of its distances. No extrapolation. Corrections apply in order: percent (× (1 + p/100)), add, or multiply (PHAK, aircraft performance)

Accuracy: Exact interpolation of the table as entered; real performance between table rows is not linear, and the table is only as good as the book it came from

Worked example: Takeoff distance at 3,000 ft and 25 °C, less 10% for a headwind. Source: add-aviation-suite bilinear scenario: the four cells around 3,000 ft and 25 °C.

You enter

Look up first variable at
3000
Second variable at
25
Corrections
10 kt headwind, percent, -10
Variable names
pressure altitude, temperature
Table
0, 0, 1000 0, 10, 1070 0, 20, 1145 0, 30, 1225 2000, 0, 1150 2000, 10, 1235 2000, 20, 1325 2000, 30, 1420 4000, 0, 1335 4000, 10, 1435 4000, 20, 1540 4000, 30, 1655

You get

Answer
1,336.5
From the table
1,485

Review: Not yet independently reviewed by a flight instructor (CFI).

Last verified: 2026-09-19, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.

Status: version 1.0.0, core 0.1.0. See this tool in the verification report.

Checked against: 13 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.

Sources

Experimental means this tool has not yet met the stable bar: at least 20 golden vectors, differential tests, and an independent worked example.