I made a post recently about how the TCH in MSFS is consistently too high due to a problem with the G/S signal. I wondered what data Navigraph use for the G/S elevation? Is it the height of the antenna, or the field elevation at the location of the G/S antenna? If it’s the former, then this could explain why the G/S is consistently high in the final stages of approach; the G/S fly up/down signals aren’t centred at the very top of the antenna, more like 1/2 down.
Hi,
No, according to the internal valid ARINC424 specification, it´s the GS antenna elevation in feet. There are no information about the antenna height in the ARINC424 database.
Cheers,
Richard
That’s an issue the FenixSim A320 add-on owners are well aware of. That add-on uses navigraph G/S data and it always shows too high.
On short final, the G/S also usually “freezes” for a second or two, causing the aircraft to level off slightly, and as the G/S starts moving again, the aircraft has to “catch up”.
Regardless, using aircraft that use the data from the airport scenery devs, it works accurately. When flying aircraft that use the navigraph data, the g/s is always too high, leading to long landings if you follow the glide slope all the way down, or a “glideslope, glideslope!” aural warning should you ignore it and cross thresh at 50 feet.
Many of us set the “G/S MODE” to OFF on the overhead so that we dont get the glideslope aural warning.
In which case the G/S signal should terminate and intersect the ground at the location of the G/S antenna, but it doesn’t.
Please look at the post above … It seems to be a known Fenix issue. We only offer the data but have no influence on how the addons use the data.
As I have written, we offer the glideslope antenna elevation in feet on their position.
Cheers
Richard
I’m not sure I understand what you mean. Addons don’t make interpretations of the G/S data, it is imported into MSFS and presented via the G/S deviation pointer in the same way on all aircraft (instrumentation dependent). We are not referring to the FMC/FMGC data, but the G/S information that is imported directly into the simulator.
I found a previous post that referred to this at a particular airport and a screenshot was provided by Navigraph to demonstrate that everything was working as expected. While the screenshot does depict the aircraft sitting 50ft above the threshold, it can clearly be seen on the PFD that the glide slope pointer is showing a full ‘fly-up’ indication. This confirms that the glide slope signal within the simulator is not intersecting the antenna at either the correct location or correct elevation.
… and that is not correct. Fenix works independently of the sim, meaning it doesn´t use any data from the sim—it uses its internal database for navigation and flying. We have a good example for that in the past days here:
In this example, the airport ICAO code was wrong, and the sim had no ILS. However, you can fly this in the Fenix add-on, but not in the stock or any other add-on aircraft. Fenix uses its database for all the calculations, not only for the FMS/Navigation.
We must trust our data and data provider so the G/S elevation is correct, but we have no idea about the elevation in the sim. Are they correctly implemented?
Here is another good/confirmed example for a bad elevation:
In other words, even when the elevation data in the Fenix is correct (and again, they used the published AIP data), that doesn´t mean that the elevation in the sim is 100% accurate.
I hope it makes it all a little bit clearer
Richard
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