Mode ILS

ILS: left / right of the runway centreline and above / below the glide path.

Group	Aviation
Default frequency	110.3 MHz
Default sample rate	2 Msps
In the mode list	Localizer and glide slope

Step-by-step: Tutorial-ILS

What ILS is

The Instrument Landing System guides aircraft down to the runway with a localizer, a glide slope and marker beacons.

Frequencies and settings

Approach guidance, 75 / 108 - 112 / 329 - 335 MHz.

Setting	Value
Start frequency	110.3 MHz
Tuning range of the mode table	74 to 336 MHz
Sample rate asked	2 Msps
Lowest working rate	100 ksps
Channel width	50 kHz

OnAir takes any frequency you type; the numbers above are the mode's starting point and the range its table describes. In the app the shortcut label is Localizer and glide slope.

What OnAir shows

Localizer and glide slope needles (DDM), marker beacons, identification.

The mode's own tab has these screens: Approach, Stations. The other tabs (Overview, Receiver, Scan, History) are described on the Main window page.

Tips and caveats

• Checked with generated signals and impairments; recordings of real signals welcome.
• Which radio: Usually yes for narrowband signals: an RTL-SDR tunes roughly 24 MHz to 1.7 GHz at up to about 2.4 Msps. Wide signals such as TV channels need a faster radio, and OnAir says next to the source what the selected radio can do.
• Try it without a radio: most modes include a built-in synthetic test signal, so you can open the screen and try the controls first.
• Receiving and the law: Receiving aircraft broadcasts is legal in many countries, but some restrict listening to or using what you hear. OnAir is a receiver. Check the rules where you live. See Legal.

Related pages

• All modes, Aviation
• Supported radios, Troubleshooting, FAQ
• More in Aviation: ADS-B, Mode S uplink, ACARS, VDL2, VDL4, HFDL, Airband, VOR, NDB, Drone Remote ID, UAT, FLARM, DJI drones