I love this discussion
Just a few quick points before I hit the sack, somewhat tired on a fatal overrun investigation at the moment...
1. The beam needs to be good enough. There is no way that you have sufficient information in the cockpit to determine this. There is no legal requirement to publish the information about the "straightness" of the beams for a CAT I ILS.
2. Some very large airports to not protect the ILS GP anything like enough in visual conditions. If a 744 taxies in front of the GP, then in certain conditions, it can deflect the beam to 1 degree, which would make your approach fun. Hence some of the reasons for LVPs at airports.
3. The wrong holding points will be in use, hence potential interference.
4. Some idiot at the airport will have decided not to protect the instrument runway strip and have work going on there as the runway landings are visual. Australia especially bad at this. If you fall off, you could be in trouble.
5. Beam deflection from the aircraft ahead on approach (had a GP drop out with this, but very unusual) but LOC can go all over the place, as well as the deviation swing of LOC from the overflight.
6. The terrain may upset your radalt based calls. Hence, if you look in the UK Integrated AIP, you will find a special note about Manchester and CAT II operations onto Runway 06L, as an example. (too late for me to remember if it is an AIC or an AIS) but applies to C/D categories of approach speed but not A/B
7. The terrain may upset the automatics, it can be fun to watch them on autoland trials with downhill runways, having had an uphill approach, float, float, float ooops spool up go-around.
8. Do you have a safety management system agreement with the airport operator and air navigation service provider at this point for your own legal protection. (Not at the last 50 airports I check audited, you don't.) So, if you kill someone when you fall off, expect to go to jail for manslaughter.
9. how long to you need to be stable for, ATC vectoring may well be too tight for the system to cope with. You guys are always calling "established" when you aren't locked on, tracking and happy. Just because something changes colour in the cockpit, does not mean that you are, it might mean that the machine is now in the mode where it is trying to!
10. power supply requirements are quite different and can lead to transient changes in the signal generated, as well as the lights going out!
11. Some ILS LOC signals allow for roll out guidance, but can be very wonky in the 100 foot area, expect a disconnect at any point. When was the last time that you practiced an autopilot disconnect in autoland configuration below DA? Try it at 70 feet in an aircraft with underslung engines and all that nice trim in. Yep, the 737-200 would be fun. Can you get a landing out of it, or are you going to go around at this point? Answers to your Head of Flight Training on a postcard please (OK, some airlines do it, but a few that I know do not!)
So, if you want to do it and not end up in jail, or without a job, then make sure that your planning department has done their work on the Airport PATC (if they even publish it, which they do not for CAT I facilities...) in AIP GEN AD2, they have seen the flight check (which will not go down that far if they have only been paid for a CAT I flight check, in some countries) and it is acceptable, if your insurance company approves it (if your flight operations department even thinks of that one), that the airport has been audit by your men under JAR OPS 1.220 and that the full infrastructure is available (does any airline actually did the full audit anymore, other than counting the fire engines, although I have done a few for a couple of nameless airlines), that ATC and the airport operator have integrated their safety management systems (if they are different organisations) and that your SMS is integrated with theirs (plus operational procedures etc) and so on. Once you have done all of that, and got permission from the airport and ATC insurance companies blah blah, then please, go ahead.
Actually, lots of airports in the US have this ability, but they have the FAA to think about it and approve it. Same in UK. Netherlands publishes some non-standard information about their ILS beams so residents can do it.
If you have any doubts about any element of the list above, which is not complete, and you do not have a specific company instruction listing the runways you may use and any other operational considerations, then I would suggest that you might like to land manually, for your own legal protection.