fraroc Posted April 12, 2022 Share Posted April 12, 2022 I use a combination of GPS for the flight and then switch to heading mode so I can work on my approach with the autopilot dials to line me up with the airport. I did a long haul O'Hare to De Gaulle flight that went off with no problems whatsoever. So then I attempted a short flight from Toronto to O'Hare and I did the same exact thing, except when I intercepted the glideslope for runway 22R, the autopilot proceeded to do a 180 turn AWAY from the airport. I tried it again, did the same thing. What causes this to happen? What did I mess up? Link to comment Share on other sites More sharing options...
mrzippy Posted April 12, 2022 Share Posted April 12, 2022 NAV 1 freq set to 111.30? Wonder if you are picking up another runway ILS from a nearby airport? Still thinking about a new flightsim only computer! Link to comment Share on other sites More sharing options...
fraroc Posted April 12, 2022 Author Share Posted April 12, 2022 NAV 1 freq set to 111.30? Wonder if you are picking up another runway ILS from a nearby airport? Yes that what the frequency was set to....Do you think it's because I didn't use the ATC? Link to comment Share on other sites More sharing options...
fraroc Posted April 13, 2022 Author Share Posted April 13, 2022 its turning me around over the water though and when it completes the turn, I'm not under the glideslope anymore. Seriously, what is causing this to happen?! Link to comment Share on other sites More sharing options...
lnuss Posted April 13, 2022 Share Posted April 13, 2022 (edited) My first question is what was your heading when you "intercepted the glideslope for runway 22R" and also WHERE were you at that moment? And how far out? And which way did the localizer needle point? Another question is whether you also had another radio tuned to Northbrook (OBK) to mark the intersections, and what was its OBS set to? And finally, you're certain you were on NAV rather than GPS on the GPS/NAV switch? Some of the above is pretty basic, but I wasn't able to see what was going on at that time, and I can think of several possible causes, but which, if any, is dependent on the answers to the above. Addendum: its turning me around over the water though and when it completes the turn, I'm not under the glideslope anymore. Are you saying that it made you climb, or just that you wound up off to one side (if so, which?)? Edited April 13, 2022 by lnuss Larry N. As Skylab would say: Remember: Aviation is NOT an exact Science! Link to comment Share on other sites More sharing options...
lnuss Posted April 13, 2022 Share Posted April 13, 2022 Do you think it's because I didn't use the ATC? No, that wouldn't have anything to do with it. That's just verbal communication and doesn't affect the aircraft or the procedures except when the communication causes you to take some action. Larry N. As Skylab would say: Remember: Aviation is NOT an exact Science! Link to comment Share on other sites More sharing options...
fraroc Posted April 13, 2022 Author Share Posted April 13, 2022 My first question is what was your heading when you "intercepted the glideslope for runway 22R" and also WHERE were you at that moment? And how far out? And which way did the localizer needle point? Another question is whether you also had another radio tuned to Northbrook (OBK) to mark the intersections, and what was its OBS set to? And finally, you're certain you were on NAV rather than GPS on the GPS/NAV switch? Some of the above is pretty basic, but I wasn't able to see what was going on at that time, and I can think of several possible causes, but which, if any, is dependent on the answers to the above. Addendum: Are you saying that it made you climb, or just that you wound up off to one side (if so, which?)? I believe that my heading was around 230 or so, kinda around the heading of the runway itself and I was approximately 26 or so NM away from the runway at like 2500 or 3000ft. I really wanted to make sure I was underneath the glideslope so I didn't miss the approach. It should have just turned me twoard's the runway so I could set up a nice smooth landing. I mean, it could be possible that NAV2 was causing issues because the panel I was using (I was flying the default MD-80 with a custom MD-80 panel) had the two radios on at all time with no way to shut it off, but I recall something similar happening in the CLS 747 during a long haul flight, where I'd be ready to incercept the glideslope and then all the sudden, it turns in the complete opposite direction of the airport. It didn't make me climb, but it made me lose the diamonds and make the radio stop beeping, meaning I'm not underneath the glideslope anymore. It's like the airport is a damn magnet repelling my plane away. Link to comment Share on other sites More sharing options...
f16jockey_2 Posted April 13, 2022 Share Posted April 13, 2022 And finally, you're certain you were on NAV rather than GPS on the GPS/NAV switch? +1. You could be still in GPS mode, so the AP tries to fly to the active waypoint in your GPS. Wim Link to comment Share on other sites More sharing options...
lnuss Posted April 13, 2022 Share Posted April 13, 2022 I believe that my heading was around 230 or so, kinda around the heading of the runway itself and I was approximately 26 or so NM away from the runway at like 2500 or 3000ft. That's a long ways out to be engaging the ILS for navigation- signals are weak out there, and you likely lost the glide slope indication because the signal was too weak for the receiver to use, or just as likely because you were too far under the glides slope to receive it at all- it is angled upwards from the landing area and is not an infinite signal. The first thing to try would be to get under 20 miles before switching to ILS navigation, perhaps even a bit closer, to be sure you have a strong enough signal, and you won't actually capture the glide slope until you are near the FAF. Wikipedia has an article on the glide slope: https://en.wikipedia.org/wiki/Instrument_landing_system_glide_path Wiki also has an article on the ILS system itself: https://en.wikipedia.org/wiki/Instrument_landing_system You might also want to read the FAA's Instrument Flying Handbook where you can learn a lot: https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/FAA-H-8083-15B.pdf In Chapter 9 on page 9-40 starts the discussion on ILS itself, though there are other places where some info about it shows up. The table of contents will show where all the different types of information are. Larry N. As Skylab would say: Remember: Aviation is NOT an exact Science! Link to comment Share on other sites More sharing options...
mrzippy Posted April 13, 2022 Share Posted April 13, 2022 Larry is spot on (as always!). IIRC, I would normally start to hear the ILS MORSE code starting around 26 miles out. ATC would then give me the turn to about 30 degrees short of the runway heading. My altitude at that time would be around 2000 feet above the runway. By 20 miles out, or so, I would capture the localizer and begin the turn towards the runway and at 16 miles out capture the glideslope and begin descent towards the runway. Depending upon which airport you are flying into, some ILS landings can be pretty tricky due to the terrain. I found Palm Springs Airport to be like that! :eek: Still thinking about a new flightsim only computer! Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now