Taking off without updating VLF and without updating position data doesn't really seem to matter?
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I've several times now tried departing without updating the VLF position, and without updating position data, leaving it saying position uncertain to experience what will happen with inaccurate data. I am not using the GNS at all. Weirdly, doing this seems to have no effect on navigation. Shouldn't I be off course when navigating with waypoints using the FMS? Even without setting VORs to autotune, there still seems to be basically no appreciable loss of navigational accuracy. This is in 2024 SU3.
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I was curious about this too and did a deep-dive into the code a while back. As far as I can tell, Starship does not actually track the VLF/Omega signal. In fact, it's sort of backwards, in that the sim always knows the position of the plane, and the VLF/Omega math simply (well, not so simply actually) back-calculates the VLF/Omega signal strengths and other values relative to that.
For more than you wanted to know about VLF/Omega, I started a thread here:
https://community.justflight.com/topic/9032/down-the-rabbit-hole-with-vlf-omegaYou can do actual Omega navigation with a free 3rd party emulator that runs outside the sim. It emulates the manual plotting form of early Omega navigation, with a receiver displaying station pairs and lane counters, and corresponding charts. Works for either 2020 or 2024.
https://flightsim.to/file/74110/omega-navigation-system -
This post is deleted!
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thanks for the links. I may try my next flight with the GPS breaker pulled so I'm not getting any data from the integrated GPS either and see if that makes any difference.
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I've several times now tried departing without updating the VLF position, and without updating position data, leaving it saying position uncertain to experience what will happen with inaccurate data. I am not using the GNS at all. Weirdly, doing this seems to have no effect on navigation. Shouldn't I be off course when navigating with waypoints using the FMS? Even without setting VORs to autotune, there still seems to be basically no appreciable loss of navigational accuracy. This is in 2024 SU3.
@rinkerbuck said in Taking off without updating VLF and without updating position data doesn't really seem to matter?:
... Even without setting VORs to autotune, there still seems to be basically no appreciable loss of navigational accuracy. This is in 2024 SU3.
There are more DME receivers than just the two that can be tuned manual or automatic. You check what the others are receiving on the MFD and if it is used to calculate your position.
I have been thinking about taking the Starship flying in some remote area without radio beacons in range to play with the navigation. Haven't gotten around to it yet.
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Today I took off with GPS disabled by the breaker, and never did update position or VLF. I do see a small discrepancy between FMS position and the position I am getting from VLF, but no issues with navigation. I am not even getting the "degraded" warning message, and the MSG notification to update VLF went away on its own. Something seems to be off here. Or... the DME and VLF/Omega updates are just "that good". Still I think it's weird I am not getting a warning and that the request to update just went away magically.
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Today I took off with GPS disabled by the breaker, and never did update position or VLF. I do see a small discrepancy between FMS position and the position I am getting from VLF, but no issues with navigation. I am not even getting the "degraded" warning message, and the MSG notification to update VLF went away on its own. Something seems to be off here. Or... the DME and VLF/Omega updates are just "that good". Still I think it's weird I am not getting a warning and that the request to update just went away magically.
@rinkerbuck said in Taking off without updating VLF and without updating position data doesn't really seem to matter?:
Or... the DME and VLF/Omega updates are just "that good". Still I think it's weird I am not getting a warning and that the request to update just went away magically.
That depends where, when, and what conditions you are flying in. If you choose a daytime, low altitude flight located far away from the VLF transmitters, and far away from DME transmitters, then you should get the warning messages you're looking for soon enough. The message went away after you took off as the aircraft automatically improved its positional estimate with all the available sources. You can also disable all the position sources in the CDU's menus, to test this for yourself.
EDIT: As for how good the DME/VOR/VLF position is... that's all there was in that airplane before the LRN was added
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Thanks for the reply. Will have to experiment more.
