# Can the ILS be shut down? [closed]

Can the ILS be manually turned off? Not by the pilots inside the cockpit by simply shutting of the ILS button, but rather by a 3rd party personnel, such as an ATC or a ground crew member.

ATC shuts off ILS on RWY 05L for safety reasons.. or traffic separation reasons.

I am a second year electronics and communications student, so if you would like to use a couple of technical terms, i can understand them, to some extent

• An ILS is powered by electricity, so of course it is possible to shut it off. Your question is unclear. – GdD Nov 6 '15 at 10:47
• not asking why, i'm asking how could they be shut down. A matter of How rather than why. – Fady Abouelghit Nov 6 '15 at 13:34
• How? By turning off the power. The same way you could shut down a radio or TV transmitter. If there's no power, there's no transmission. – Zach Lipton Nov 6 '15 at 21:10
• I'm wondering how exactly you think shutting down ILS would solve traffic separation issues... – Sanchises Nov 7 '15 at 15:19

The ILS, or precisely the components localizer and glidepath antennas can be shut off, as they are electronic devices that emit radio signals. They can be turned off and on by ATC where required, e.g. having the same ILS frequency for two opposite runways and you only want one to be active at the same time or they can be shut down by maintenance directly at the emitters. ILS are usually not powered by UPS, so they will not be available during power outages.

If equipment is being shut down for maintenance or other reasons, you will see this mentioned in the NOTAM, such as here from Cologne/Bonn Airport, where the glidepath portion of the ILS runway 24 is out of service:

A4932/15 - ILS GP RWY 24 OUT OF SERVICE. 01 OCT 00:00 2015 UNTIL 30 DEC 00:00 2015 ESTIMATED.
CREATED: 27 AUG 13:34 2015


(Source: NOTAM EDDK)

Yes.

Usually, shutting down the ILS means shutting down the localizer and glideslope signals. There is more than one reason to 'shut down' the ILS.

The ILS is designed to shut down automatically on detection of fault. FOr example, if the primary transmitter (of glideslope) malfunctions, the system will automatically transfer to the standby transmitter. If that fails or if the standby transmitter also malfunctions, the system automatically will shut down, with ATC being automatically informed. Cat III ILS systems are required to shut down within 2 seconds of fault detection.

FAA carries out flight check operations on various navigational aids in airports and can require the ATC to shut down the ILS if error is more than limits.

ILS can be shut down because of equipment change, maintenance etc. Of course, if the power goes out, ILS goes out with it.

As per regulations, any shutdown of ILS (or any other navaid) is to be informed via NOTAM.

• "if the power goes out, ILS goes out with it": FAA requires a second power source to be used as a backup (I think ICAO as well). Order 8400.13D: "The LOC, glideslope, and inner marker (if operationally required) must have an approved backup power source which provides an uninterrupted power supply in the event of a primary power source outage.". – mins Nov 7 '15 at 0:17
• @mins True, but Murphy's law applies :) For example, see here – aeroalias Nov 7 '15 at 0:33
• Indeed :) Interesting page and stories, including this one. – mins Nov 7 '15 at 9:20