RobertGary1 Posted September 21, 2020 Report Share Posted September 21, 2020 Why are almost all ILS's marked as not valid as an alternate airport when the tower is closed? I know the towers monitor the ILS but the ILS itself is still a legal approach, but you just can't use it as an alternate airport. -Robert Quote Link to comment Share on other sites More sharing options...
rbridges Posted September 21, 2020 Report Share Posted September 21, 2020 8 minutes ago, RobertGary1 said: Why are almost all ILS's marked as not valid as an alternate airport when the tower is closed? I know the towers monitor the ILS but the ILS itself is still a legal approach, but you just can't use it as an alternate airport. -Robert I didn't know that was a thing. I don't do much night flying, so maybe that's it, but I'd be interested in the answer, too. Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted September 21, 2020 Report Share Posted September 21, 2020 It seems that it has to do with protecting the ILS critical area. When the tower is closed, there is no guarantee that there is no airplane or vehicle in the critical area. 2 Quote Link to comment Share on other sites More sharing options...
Steve W Posted September 21, 2020 Report Share Posted September 21, 2020 33 minutes ago, N201MKTurbo said: It seems that it has to do with protecting the ILS critical area. When the tower is closed, there is no guarantee that there is no airplane or vehicle in the critical area. There are plenty of airports with no tower at all that are allowed as planned alternates, there's no protection there. Quote Link to comment Share on other sites More sharing options...
GeeBee Posted September 21, 2020 Report Share Posted September 21, 2020 It has to do with monitoring. A lot of towers used to be open 24/7 so no remote monitoring equipment was installed. Now that more towers are closed, the equipment is incapable of monitoring because remote monitoring was not installed. As to critical areas, the uncontrolled airport I fly out of has a critical area, but of course you are dependent upon others not intruding. Best way out is to have WAAS GPS, LPV capability. Also remember, when you go missed at your destination, you do not have to go to your filed alternate. In fact, ATC does not know what your is filed alternate. If you decide to divert, pick an airport and go for it. I regularly file KATL as an alternate even though I have absolutely no intention of using it. I am more likely to go to KPDK or other area airport, but KATL is an easy file because it is manned 24/7, has everything on 5 different slabs of concrete and has a 24h TAF. 2 Quote Link to comment Share on other sites More sharing options...
carusoam Posted September 21, 2020 Report Share Posted September 21, 2020 Listening for the code for the ILS... can be helpful as you get closer... This way, you know, they left it in running condition as they left for the day... There must be a half dozen things that could change while nobody monitors the ground based system... So... how reliable is an unmonitored ILS? Probably good for everything but... low IFR... As there would be no way to know if somebody has left a plane in the way of the antenna sensitive areas... PP thoughts only, not a CFII... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
RobertGary1 Posted September 21, 2020 Author Report Share Posted September 21, 2020 1 hour ago, carusoam said: So... how reliable is an unmonitored ILS? Probably good for everything but... low IFR... As there would be no way to know if somebody has left a plane in the way of the antenna sensitive areas... But the thing is its still perfectly legal to fly the ILS to mins when the tower is closed. You just can't use the ILS as a basis for filing that airport as an alternate. -Robert 2 1 Quote Link to comment Share on other sites More sharing options...
kpaul Posted September 23, 2020 Report Share Posted September 23, 2020 On 9/21/2020 at 5:11 PM, RobertGary1 said: But the thing is its still perfectly legal to fly the ILS to mins when the tower is closed. You just can't use the ILS as a basis for filing that airport as an alternate. -Robert It has to do with the ILS not being monitored. You would not want to go missed approach at your intended destination, then fly to your alternate only to find out the ILS is not operational, but since one one is in the tower there was not a NOTAM. Now you are short on fuel because you used your alternate gas getting to this approach. Quote Link to comment Share on other sites More sharing options...
RobertGary1 Posted September 23, 2020 Author Report Share Posted September 23, 2020 4 hours ago, kpaul said: It has to do with the ILS not being monitored. You would not want to go missed approach at your intended destination, then fly to your alternate only to find out the ILS is not operational, but since one one is in the tower there was not a NOTAM. Now you are short on fuel because you used your alternate gas getting to this approach. That probably makes the most sense. But how does that apply to non-towered ILS's. Are they just remotely monitored? -Robert Quote Link to comment Share on other sites More sharing options...
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