Sometimes the ILS just goes haywire, for many reasons as we all know. This happens to me, so when it does, I just take it as ILS malfunction, turn off AP and fly in manually. Not just MSFS, but I have to assume that in real life, at anytime, the ILS in the plane can just malfunction and the pilot has to take over 100% manual? I never flown, thus have no idea.
I’d guess it is more likely that a rw pilot tricks his/herself into believing the ILS is malfunctioning when it is in fact not.
I just want to make a distinction, here. An instrument landing system is two radio signals at the airport, a localizer and a glideslope. If that were to be out of service for some reason, you would know about it ahead of time via NOTAMs. Or if it were to become unavailable while in-flight, at a controlled airport, someone is probably going to tell you about it.
I assume that your question is really about the avionics in your aircraft. If they were to be inoperative in some way, you could potentially fly another type of approach if one were available and you had the equipment to do it. If you are in instrument meteorological conditions (IMC) with no way to land at that airport, you could divert to another airport. Barring all of those, you could declare an emergency with ATC and they would give you special attention and help.
In the real world, if you were to discover that one of your systems was inoperative before taking a flight, it would be incumbent upon you, as the pilot in command, to decide whether or not you should take that flight with that equipment.
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The other aspect is the type of equipment you’re flying and if you’re with a Co-Pilot. Usually you cross check instrument readouts during critical flight phases like Take Off, Approach and Landing. If your display and the COP isn’t agreeing, you need to reconcile why and if needed, stop the action until confidence is gained on what’s actually happening.
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Navaids have integrity monitoring systems embedded in them. If the systems monitoring the Localiser and Glideslope detect an anomaly that exceeds preset limits, they will warn the tower controller and can even stop transmitting the signals. Without getting bogged down in complex radio engineering detail, a VOR-DME for example will stop transmitting the VOR element if it self-diagnoses a fault, but the separate DME system may continue broadcasting.
Some aircraft also have integrity monitoring. Some Airbus aircraft for example will activate the red autoland warning light on the glareshield if on a CAT2/3 approach for example it detects either a loss of signal, or excessive LOC or GS deviation. (as a malfunctioning localiser or glideslope transmitter may mistakenly indicate…or be caused by the incursion of a vehicle or aircraft into the critical area -
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Unfortunately, the OP has not been trained in the actual use of an Autopilot to follow an ILS radio signal to land a plane, and, as you noticed, is using the wrong terminology.
OP, it is not the ILS going haywire in MSFS, it is the Autopilot controlling the plane that goes haywire. As @N316TS noted, an ILS is merely a radio beam emanating from an airport which either works or doesn’t, and, as he noted, the pilot will know if it’s working before he tries to align to it. It’s far more likely the receiver in the airplane that is out of commission, and that’s not likely either if the plane has been properly maintained.
I fly mostly planes from the 70’s and 80’s with no autopilot, so I have nothing further to add, other than that I’ve always flown my ILS approaches by hand and can’t really imagine leaving that task to an autopilot. I don’t even know how many planes outside of the airlines that have autopilots that are certified to fly an ILS to the ground. I wouldn’t expect it to be very many, but I could very well be wrong about that.
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There are a lot of real world ILS issues that are not simulated in MSFS.
For example attempting to capture the glide slope from too far above will often result in capturing a “false” or secondary glideslope.
The norm is to land manually, even in large airliners. Autolands can be done but are typically reserved for extremely low visibility ops.
Now, using the autopilot to fly a coupled ILS for some portion of the approach is more common. The pilot flying will usually disconnect the automation at some point and finish the approach and landing manually. That could happen at the marker, it could happen at minimums, or even before joining the localizer in order to fly the entire ILS manually. This is at the discretion of the crew, but manual approaches at the airlines aren’t in any way unusual.
As far as ILS malfunctions that drive this, I’m not sure I’ve ever seen this happen in my 23 years at the airlines. What is more common is for the tower to taxi an aircraft across the runway you’re on approach to, causing the glideslope to flicker erratically. If the autopilot is coupled at that point, it can pitch around aggressively to attempt to keep this flickering glideslope centered, and so the norm would be to disconnect and fly manually so you can smooth that out and wait for a good glideslope to return.
But you don’t need an excuse to fly. Go ahead and just disconnect and fly! That’s the whole point of being a pilot ;).
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Great answer from another Instrument Rated Multi-Engine Commercial pilot!
Yes to everything you have posted. Just adding…
Back to the idea of avionics vs AP fail, if certain systems fail, air data as an example while IFR, we have to report that to ATC. This is important for the controller to know because if my air data is wrong, how can i be expected to maintain altitude? The controller has to make sure to give me extra room to ensure separation from others, esp if im in RVSM or Terminal airspace.
If AP fails, im expected to hand fly. After all, no AP on instrument checkride to ensure you can control the plane. The AP is intended to make flying easier - we’re expected to control the AP, which in turn controls the airplane on our behalf.
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Never happened to me in 20 years of airliner flying.
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Whilst rare, ILS signal deviations and fluctuations do happen in real life. Often due to taxing aircraft momentarily passing in front of the LOC or GS transmitter.
It is a particularly frequent and problematic issue in Hong Kong, especially during single runway ops. There have been multiple incidents, over a number of years, ranging from relatively benign go-arounds to aircraft becoming significantly unstable and terrain clearances compromised.
Here is part of the warning published by the HK Civil Aviation Department.
During normal operations when ILS CAT I conditions are applicable, aircraft or vehicles entering the localiser and glidepath sensitive areas could cause interference to the ILS signals that may result in significant localiser and/or glide slope signal deviations. Therefore pilots should anticipate the possibility of this interference, closely monitor their ILS profile, particularly the rate of descent, and be prepared to take immediate appropriate actions if excessive disturbances are experienced.
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Yeah Hong Kong definitely needs to implement some kind of protection. You can be quite close to terrain when you’re further back on the approach. Certainly gets your attention when it happens!
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