Glide Slope Angle Calculator

Work out glide slope angle instantly with clear inputs, formula shown and shareable results.

About Glide Slope Angle Calculator

Glide slope angle is the arctangent of height divided by horizontal distance in the same units. A standard 3 degree ILS path passes 1,000 ft above the threshold elevation at 3.2 nautical miles, or about 318 ft per nautical mile — the check most pilots use to confirm they are on profile.

Formula

Glide slope

angle = atan(height / (distance x 6076.12)); ROD = ft per nm x GS / 60

Worked example

With the default values below, Glide Slope Angle Calculator returns Glide slope angle of 3.02. Change any input above and every figure here is recalculated in your browser.

Inputs used

Distance from the threshold: 5 nm
Height above threshold elevation: 1,600 ft
Ground speed: 130 kt

Results

Glide slope angle: 3.02 °
Height per nautical mile: 320 ft/nm
Rate of descent to hold it: 693 ft/min
Deviation from a 3 degree path: 0.02 °

Step by step

1Values used
2Glide slope
3Glide slope angle= 3.02 °
4Height per nautical mile= 320 ft/nm
5Rate of descent to hold it= 693 ft/min
6Deviation from a 3 degree path= 0.02 °

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

Frequently Asked Questions

What does 3 degrees mean in feet per mile?

About 318 ft per nautical mile, so at 10 nm a 3 degree path is roughly 3,200 ft above threshold elevation.

When are steeper approaches used?

Terrain or noise constraints force 3.5-5.5 degree profiles at some airports, and those require specific aircraft and crew approval.