Navigational data - how accurate is X-Plane?

[pirx2015]

Hi,

 

I'm fairly new to XPlane - flying for about a month now. However I noticed some strange behavior in the area of navigation. At least I cannot understand what is going on. For some reason I'm having a real difficulty to track a VOR. When I intercept a radial and fly the corresponding HDG the CDI shifts nevertheless, to quite a considerable deviation. One way to mitigate is to fly a HDG which is a couple of degrees off. For example to track radial 286 I need to fly HDG 283. Does anyone know what could be the reason for that?

 

Another problem I saw - there is some radial mismatch between the X-Plane VOR radials and HDG info from sites like Skyvector. I know that X-Plane does not have the most up to date data. On the other hand neither does Skyvector, so how do you navigate?

 

I'm flying in CAVOK conditions, no wind, so weather is not an issue. I'm also using AP so nothing to do with my beginner flying skills

 

Really appreciate your help. Thanks!

[PinkJackal]

X-plane does have the most up to date data, it's using navigraph AIRAC!!! 

[eMko]

If you have the latest AIRAC from Navigraph, you can update the X-Plane's database. However it can mean that the ILS can get misaligned with the runway or if the runway number changes (which happens also in real world). But it should not happen with VORs.

 

However if you have never updated the X-Plane nav data and you are using skyvector with today's data, then it can be messy. Reason for this is that the magnetic compass drifts with time - in some parts of the world it's more noticeable than in others. And the VOR radials are based on magnetic headings, therefore you need fresh navigation data and maps at least once a year.

[pirx2015]

X-plane does have the most up to date data, it's using navigraph AIRAC!!! 

 

 

If you have the latest AIRAC from Navigraph, you can update the X-Plane's database. However it can mean that the ILS can get misaligned with the runway or if the runway number changes (which happens also in real world). But it should not happen with VORs.

 

However if you have never updated the X-Plane nav data and you are using skyvector with today's data, then it can be messy. Reason for this is that the magnetic compass drifts with time - in some parts of the world it's more noticeable than in others. And the VOR radials are based on magnetic headings, therefore you need fresh navigation data and maps at least once a year.

 

 

Thanks PinkJackal and eMko!

 

I guess if I wanted to use real data from sites like Skyvector/Fltplan I would need to have the most up to date cycle from navigraph. I might do so in the future, but in the meantime I don't mind flying HDG 181 instead of HDG 179. What I do care about is being able to do a reliable Flight Planning, which is quite difficult when XPlane and available tools look at different data sets!

 

So how do people do Flight Planning in XPlane? I deliberetaly avoid GPS navigation at this point as I want to master a more basic approach with VORs/NDBs/Visual. Needless to say that XPlane's own local map does not provide enough details for an accurate plan.

 

I did find Plan-G - which is AWESOME as it reads XPlane data. Brilliant! Are there other tools that do not require updating AIRACs?

 

Thanks again!

[eMko]

Basically I use the Plan-G for VFR flight planning and as a backup navigation device for every flight (it can display your actual position and heading/time for a certain waypoint (just click right mouse button anywhere on the map and select the option from context menu)) - the aircraft navigation system can fail (either due to a software bug or due to a pilot error - I encountered both) and this can buy time to fix it.

 

For simplistic planning of IFR flights when the navigation is based on VORs and ADFs it's also enough. You can even create a flight plan and export to X-Plane so you'll be able to load it to GPS or XCIVA. However if you want to have an IFR flight plan based on air routes, with SIDs, STARs and altitude constraints, it's lacking. I use the real world charts for planning an IFR flights - you can obtain both enroute and airport charts from Navigraph or use some real world charts if you have a "cheap source" because they cost more money than they're worth for flight simming (i.e. real world pilot who will hand it over to you when he will not need it anymore - after a month they are considered outdated and (at least here) it's illegal to use them for real world aviation). Skyvector.com is fine when you have the latest (or let's say "not older than 1/4 - 1/2 year") data in X-Plane. Other popular options for X-Plane are EFASS (http://froom.de/efass/) or PFPX (http://www.flightsimsoft.com/pfpx/).

 

As for basic principles of navigation (and yes, your attitude is 100% right: you definitely should know it if you want to use more sophisticated methods like GPS or FMCs), I learnt them from this: http://www.navfltsm.addr.com/index.htm. I know that the site looks very ugly. I was learning the basics of navigation during the golden era of Microsoft Flight Simulator 98 and the site basically didn't change since then :-D .

Edited February 11, 2015 by eMko

[pirx2015]

Basically I use the Plan-G for VFR flight planning and as a backup navigation device for every flight (it can display your actual position and heading/time for a certain waypoint (just click right mouse button anywhere on the map and select the option from context menu)) - the aircraft navigation system can fail (either due to a software bug or due to a pilot error - I encountered both) and this can buy time to fix it.

 

For simplistic planning of IFR flights when the navigation is based on VORs and ADFs it's also enough. You can even create a flight plan and export to X-Plane so you'll be able to load it to GPS or XCIVA. However if you want to have an IFR flight plan based on air routes, with SIDs, STARs and altitude constraints, it's lacking. I use the real world charts for planning an IFR flights - you can obtain both enroute and airport charts from Navigraph or use some real world charts if you have a "cheap source" because they cost more money than they're worth for flight simming (i.e. real world pilot who will hand it over to you when he will not need it anymore - after a month they are considered outdated and (at least here) it's illegal to use them for real world aviation). Skyvector.com is fine when you have the latest (or let's say "not older than 1/4 - 1/2 year") data in X-Plane. Other popular options for X-Plane are EFASS (http://froom.de/efass/) or PFPX (http://www.flightsimsoft.com/pfpx/).

 

As for basic principles of navigation (and yes, your attitude is 100% right: you definitely should know it if you want to use more sophisticated methods like GPS or FMCs), I learnt them from this: http://www.navfltsm.addr.com/index.htm. I know that the site looks very ugly. I was learning the basics of navigation during the golden era of Microsoft Flight Simulator 98 and the site basically didn't change since then :-D .

 

Thanks a lot for taking the time for such a detailed response and the references! My first round with flight simulation was in 1998/99 with Sierra Propilot. Back then they would ship it with a 200 page manual that covered all aspects of flight, incl. air navigation. So the website you referred me to feels like home - and the principles haven't changed much either .

 

My current focus is on VFR with Cessna 206, slowly adding night, basic IFR approaches, etc. So probably Plan-G is the best fit for now. EFASS/PFPX look impressive so I would keep them in mind once I'm advanced enough. At least I finally understand how the nav data is organized and why it is different.

 

By the way, did you try simbrief? It's for larger planes but looks great!

 

Thanks again.

[eMko]

You're welcome :-)

 

And yes, I know simbrief. I use it occasionally when I don't want to bother with fuel calculations and route planning - it's another tool which is good to have, but both EFASS or PFPX can create such briefing more accurately, because they have "more variables on the input". I'm thinking of buying one of the tools (for maybe more than a year :-) ).

[pirx2015]

I saw somewhere on the forums that EFASS had some limited support lately. Do you know if both are supported now?

[eMko]

The latest version of EFASS is from Dec 2014 and the support forum is more-or-less active. So I believe that it's supported.

 

(I actually want it to be supported, because I finally bought EFASS yesterday   )

[pirx2015]

The latest version of EFASS is from Dec 2014 and the support forum is more-or-less active. So I believe that it's supported.

 

(I actually want it to be supported, because I finally bought EFASS yesterday   )

 

Congrats! - I gotta say it does look awesome.

 

Regarding Plan-G - I give it a try yesterday and I gotta say that it is a WONDERFUL tool. I am amazed it is free - well donationware.

[Print744]

I use ForeFlight on my iPad coupled with X-Plane and it works great. The other real handy app I use is X-Mapper Pro on my iPhone. That one allows you to change frequencies, OBS and autopilot functions in a more user-friendly way, as easy as turning a real knob or pushing a real button in a real plane, vs. hunting for an elusive click zone with the mouse.

The reason I found this thread is that I'm finding a lot of the US-Pacific-Northwest VORs in X-Plane are misaligned. I'm currently (literally, in X-Plane, as we speak) right on the OTH/R-029º/D43.8, VOR locked on with the autopilot, and ForeFlight (current revision) is showing a 2.5nm right deviation.

This is just one example. I'm finding that a lot of the VORs in the area are similarly misaligned as well, some significantly more.

So, my question is: how often does Laminar update the Nav database? Is updating with AIRAC from Navigraph fairly straightforward, or is there an easier way I can do it?