# ILS Glideslope Height RNAV

For ILSILS —Instrument Landing System glideslope height questions, there are three methods to solve the problem:

1. Use trigonometry. This gives the most accurate answer, but is time consuming and requires converting between nautical miles and feet.
2. Use $RA = 60D$; this is slightly quicker and slightly less accurate, but also requires converting units.
3. Know that for every 1 nm on a 3° glideslope, your height will be 300 ft. This is the fastest and most efficient way.

To use the fastest and most efficient method:

1. Multiply the number of nautical miles from touchdown you are by 100.

This will give you your height.

Expressed as a formula, this is $h = 100RG$ where $h$ is your height in feet, $R$ is the number of nautical miles from touchdown, $G$ is your glideslope.