Why do ILS glide paths and localizers get turned off?

Question

Do they use a lot of electricity?

Do they require a lot of maintenance?

Thanks.

Answer 1

Maintenance is usually why a loc would be turned off if it's a single ILS airport.  

Generally, however, the ILS problems I run into are at controlled airports where the tower is closed for the night.  What usually happens is this ex.  runway 18 and 36... ILS to both runways.  Winds are 170 at 3 knots when the tower closes... I come in at 4:00a.m. and the winds are now 360 at 34g42.  Well, it's a stupid switch in the tower cab that controls it.  Only 1 localizer freq. can be active at a time, so all night only the ILS 18 is usable (what tower set it to when they closed) until tower opens when then they can hit the switch putting the ILS 36 in use.

The other problem is often these systems are now so old that they break... and at a lot of uncontrolled smaller airports with ILS's there usually aren't the resources to fix them immediately.  Also, they don't have controllers monitoring the systems throughout the day to insure they are working correctly.  

There usually isn't a whole lot of interference with localizer signals.   Radios are weird though... it seems like about anything can happen.

Answer 2

Government employees playing headgames with pilots?

Answer 3

they turn off the ILS when;

1. the runway is closed (so that aircraft don't accidentally line up on the wrong runway)

2. when it's under maintenance

Answer 4

They get turned off for maintenance and calibration or if the integrity of the system is suspect.  The turning off of the equipment will be accompanied by a NOTAM and the removal of the audio identifier.