Just curious about the NOTAM below:

!SMF 01/045 (KSMF A0080/19) SMF NAV ILS RWY 16L OUT OF SERVICE 1901180419-1901262359

Does that mean only the glideslope is broken so we can still do a LOC approach, or are both the localizer and glideslope broken?


It means exactly what it says. The ILS is out of service, so you can't use it.

An ILS can consist of several different elements, for example localizer, glidepath, DME, inner/middle/outer markers as well as a bunch of technical monitoring equipment, ATC control panels, warning systems and backup power supplies. Should any of these components fail, it may be required to take the entire system out of service. The NOTAM doesn't say exactly which part of the ILS is broken, but that doesn't matter, since the entire ILS is listed as unavailable. So no, you cannot expect to use the localizer.

  • $\begingroup$ Also, there's a difference between "not permitted to be used" and "not able to be used". The equipment might actually be powered up and transmitting usable signals when you arrive, but until it's "in service" you're not permitted to use it for navigation. $\endgroup$ – Steve V. Jan 22 '19 at 21:34
  • $\begingroup$ @SteveV. Very true. If, for instance, the monitoring equipment has failed, the LOC and GP may still be transmitting, but using them for navigation would not be allowed $\endgroup$ – J. Hougaard Jan 24 '19 at 7:14

GP OUT OF SERVICE is the verbiage used when only the Glide Slope is out of service, where GP is an acronym for Glide Path.


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