Description of the issue: ILS CApture and VOR/LOC Capture is not working well. The Autopilot wakes up at the last second and tries to do a sharp turn to capture any ILS or if a Course for a VOR Navigation is defined - same case. I would expect that once it senses that the radial approaches, it will start a gentle turn, but it waits until the last second and of course this leads to hunting the course. It is especially bad on ILS Capture as it destabilizes you totally. I think the autopilot logic for this needs to be improved. INS Navigation is working completely fine, the sequencing of waypoints and turning into the next course is very smooth, only the VOR/LOC navigation is lacking precision.
FREQUENCY OF ISSUE
How often does this occur for you - Every VOR/LOC capture.
REPRODUCTION STEPS
Please list clear steps you took in order to help our test team reproduce the same issue:
Tune VOR, Set course, Set heading to intercept <= 30 degrees of desired track, Set autopilot from HDG to VOR/LOC
Tune ILS, Set course, Establish heading for intercept <= 30 degrees of desired track, set Autopilot to VOR/LOC or GS AUTO.
YOUR SETTINGS
If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the User Support Hub.
What peripherals are you using, if relevant:
[PC Only] Are you using Developer Mode or have you made any changes to it?
[PC, MSFS 2020 Only] Are you using DX11 or DX12?
[PC Only] What GPU (Graphics Card) do you use?
[PC Only] What other relevant PC specs can you share?
MEDIA
Please add a screenshot or video of the issue occurring.
Don’t forget to turn on the radio master buses. Those are on the overhead panel where the CB’s are. I forgot those once and the ILS did not work. Also the Nav switch on the CP side at the bottom middle. Make sure that’s in LOC/VOR mode, and not NAV mode
All of these steps are done. The issue is not that the capture does not work, but that it springs to action at the last second and the plane starts to chase the needle left and right instead of smoothly turning into set course.
it’s up to the pilot to be properly established on ILS after reaching IAF (Initial Approach Fix)
According to international aviation standards (ICAO) and general pilot consensus, you are considered established when you are within half-scale deflection of the localizer course
I really struggle to understand why are you trying to teach me in forum how to fly and not hop in on the plane and try it out yourself in order to see what I am reporting? Test it, compare it with another plane, then come and give your feedback - is it bad or not. Thanks!
Sooo, this is a very vintage airliner and if modeled accurately, it would be up to the pilot to plan an ILS intercept in advance taking into consideration all the variables modern avionics do for today’s flight crews. Modern avionics compute flight paths for today’s pilots to follow, working out all the considerations that yesteryear’s 707 pilots would have to solve for themselves when approaching the localizer course. Of course, the model may be defective, however let us also consider the possibility that it may be accurately modeled and just very different than today’s Airbus and Boeing avionics where ILS intercept is concerned? Just a thought.
To @Nikita’s point, this is no 21st century airliner. The 707’s autopilot is incredibly rudimentary and its’ automation should not be relied on at all. There are some weird oddities with the FF 707’s autopilot that may be in need of some Working Title love, but I don’t think the late intercept of VOR radials/ILS localizers is one of them.
I am 100% with the author regarding this post. The argument that the 707’s avionics were rudimentary is not valid. This aircraft carried 100s of passengers each flight in all kinds of weather. If it weren’t capable of intercepting VORs and localizers accurately it would be having a horrific safety record. I Just flew a 4.5hr flight and was not able to easily intercept some of the inbound and/or outbound radials of VORs along the route and was forced to go with INS nav which works great by the way . Same story with ILS capture. came in on a 15 degree intercept angle and the needle would not center despite seeing that I was on course. Not to mention that annoying pitch oscillation at cruise and the constant trim wheel movemet and sound. If they could fix these 2 issues this aircraft would be heaven to fly.
Could it be airport specific? I tried an ILS approach at my hometown airport (SBVT) and couldn´t get LOC or GS to capture, and also, ADI, FD and HSI kind of seem to give incorrect markings (DME seemed ok). Then I tried an ILS approach at SBGL and it worked perfectly.
It would be interesting to know what the intercept angle was, as well as what the speed during intercept was and how far from the runway the intercept occurred.
The 707’s PB20 autopliot was state of the art when it was introduced, but rudimentary when compared to today’s modern autopilots.
When I flew 727s, we couldn’t intercept a localizer with 30 degrees and 200 kts. We would have flown right through it. We aimed to be roughly at 160 kts to intercept an ILS localizer.
I was watching a documentary about TWA 841(a B727) which almost fell out of the sky because the crew decided to pull the slats CB and allow flaps 2 to deploy and help speed up the airplane without using additional fuel. And of course the FE comes back from the lav and pushes the breaker back in and causes slats to depoly at high speed . Was this a common unspoken practice?
I don’t know whether this was a common practice since I flew the 727 many years later after that famous incident. During my 727 days it certainly was not.
However the re-rigging of the trailing edge flap system on the Super27 conversions had a similar effect as going to Flaps 2 with the leading edge devices retracted. This allowed the Super27 to reach FL 410.
I have done 4 flights since then and perhaps due to better piloting techniques I have not been able to reproduce the issue either that I had experienced earlier. But I have to tell you I would not want to be given a hold in IMC conditions . Been years since I had to calculate what type of an entry to use in a hold. And that is exactly why I love this airplane as it keeps you very busy . Have not been able to go back to fly the magenta aviation. Wouldn’t know what to do with myself 5 miutes into the flight
I have not been able to reproduce the issue either that I had experienced earlier. But I have to tell you I would not want to be given a hold in IMC conditions . Been years since I had to calculate what type of an entry to use in a hold. And that is exactly why I love this airplane as it keeps you very busy . Have not been able to go back to fly the magenta aviation. Wouldn’t know what to do with myself 5 miutes into the flight