Commercial Fixed Wing
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
ATC Issue All Types; Inflight Event / Encounter Weather / Turbulence
Flight Crew Overcame Equipment Problem
Procedure
We were on the ILS approach to Runway 04 at LGA. I was Pilot Flying; the FO (First officer) was Pilot Monitoring. The weather was overcast at about 900 feet; with approximately eight miles visibility. The approach controller had informed us earlier that we would be the last aircraft to land on Runway 04; but had not stated which runway they were switching to. I was hand flying the approach as required per the approach chart. Navigation setup on my side was green needles on the localizer; with the LGA VOR in DME hold; and I was listening to the Morse identifier on NAV 1. The approach was normal; with all checklists complete and the aircraft fully configured and at approach speed by 1500 feet AGL. At about 1200 feet AGL I heard static in my headset; but did not immediately recognize what it was. At about 1100 feet the FO called the runway in sight. I looked up briefly; but did not see it right away and so returned my attention to the instruments; and noticed that the CDI needle on the PFD (Primary Flight Display) had disappeared; and both LOC and GS in the FMA had red lines through them. The tower called us to ask if we had the airport in sight. I looked again; and this time I saw the runway clearly. We informed the tower that we did have the airport in sight; and they cleared us for a visual approach; which we accepted. At this point I realized that the static I had heard was a result of the localizer going offline and the Morse code being removed. The subsequent landing was uneventful. During the taxi-in; I noticed that the FO's PFD was displaying the identifier for the localizer to Runway 22 (mine was still in DME hold; so no identifier would have been displayed). I suspect that someone in ATC; either in the tower or elsewhere; had turned the Runway 04 localizer off in order to turn the Runway 22 localizer on (the two share a common frequency); and had done so before we had completed our approach. It is also possible that the localizer failed; though the appearance of the 22 identifier so soon afterward leads me to believe that this is not the case. Had this happened about 15 seconds earlier; we would have been in IMC with no vertical or lateral guidance; which is not a desirable state. As it was; we had just broken out of the clouds when the failure occurred.It took me a few seconds to associate the static in the headset with a NAVAID going offline; and I will be more alert to this in the future and more promptly execute a go-around. However; assuming that the localizer was turned off by ATC; they should be more mindful of who is on approach; and should not turn off the electronic guidance until the last aircraft for that approach has landed; especially in IMC. The low ceiling would have made going around off of the visual approach difficult to do had it been necessary.
Captain reported losing localizer signal while on final ILS approach to LGA.