Nellis TACAN unmonitored

M0205/18 - NELLIS TACAN UNMONITORED. 06 MAR 21:30 2018 UNTIL 05 APR 23:59 2018. CREATED: 05 MAR 23:00 2018

I managed to find an explanation.

VOR Station Signals Unmonitored VOR • VORs, VORTACs, and TACANs have an automatic course alignment and signal monitor (ACM). The ACM is usually connected to a remote alarm. When the ACM detects a malfunction, the unit switches to a standby transmitter. If the standby transmitter does not work properly, the facility will shut down. • “Unmonitored" means that there is no ability to observe the VOR’s operational status due to a problem or because the VOR was not designed to be monitored – An unmonitored VOR / DME is likely functioning normally • To use, tune and identify the unmonitored VOR • If a reliable signal is not received, notify ATC so they may confirm if the VOR is out-of-service • A reliable signal can be used – BUT maintain a constant listening watch on the frequency and vigilantly watch for flags.

ATC Facilities normally have an RSI (Remote Status Indicator) for the main NAVAIDS at the airport we provide service to. It basically tells us whether the thing is operating normally or not. If the RSI is down for some reason, that could spur the NOTAM that you referenced above. It is quite normal to see this type of NOTAM published. a reply to: gariac

a reply to: AtcGod

I forgot to mention that although I never saw this notice before, a Google search turned up a number of them. So ditto that this isn't very unusual. Finding any explanation online for the NOTAM was substantially harder.

So does the ACM make sense as well?

That is more of a question for an Airfield Systems Technician, but it sounds like it would be accurate info. a reply to: gariac

according to an Airfield Systems Technician, they are acutally doing upgrades and maintenance on TACAN and other systems at nellis and surrounding airfields