RNP modelling

[Guest Jasonfly]

Just wondering if we can look forward to this being modelled in the upcoming update and any chance the engravity CDU will feature this?CheersJason.

[michal 44]

Engravity is just piece of hardware (per my understanding) so what really matters whether PMDG's software can handle it. I don't know the answer. I presume you could get a hold of some RNP approach chart (there is one just freshly approved for the Reagan National airport in DC) and see if PMDG's LNAV and VNAV functions can handle such approach. You could try it even today since in my opinion it has little to do with having or not having the Engravity CDU. If you think that RNP approaches will be built into the database so you could simply select one - I would not count on it.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[downscc 1,327]

I wrote the bgl code for the KDCA RNAV RNP RWY19 approach up to the point of being able to use the RF type leg (Radius to Fix) and this is the kicker... sure we can sim the approach even with generic FS9 but I would LOVE to see the FMS code structure updated to accept RNP approaches including radius to fix legs.There are also RNP approaches in use at KPSP, KSFO and KSUN; all of which are RNP 3.0 (normal)... note that the approach at KDCA is RNP 0.11 (max error in nm 99% of the time).My approaches for KDCA are in the library as KDCAIAP.ZIPDan DownsKCRP

[michal 44]

I think there are some very tight mountain RNP approaches used in New Zealand and Alaska.I might add I don't think there are any 747 in real world flying RNP approaches.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[downscc 1,327]

I had to check 'cause it didn't seem right.. the first 9 of 10 747-400 flights I checked at flightaware.com were /Q equipment types, which means RNP and RVSN(or whatever it is for reduced vert sep).RNP is the wave of the future, KDFW is using RNAV DPs exclusively and each chart has a note the RNP equiped acft use RNP 2.0The PMDG FMS would probably need a major revision to accomodate the switch to ARINC Leg programming, but maybe if the wizards could figure out how to implement the radius to fix legs it could work.Dan DownsKCRP

[Guest alexhn]

Lets not forget that the /Q designator does not only apply to the ability to conduct an RNP approach, but also enroute, the seperation standards would depend on the navigational performance of the aircraft.

[michal 44]

>equipment types, which means RNP and RVSN(or whatever it is>for reduced vert sep).They are no doubt "RNP" capable - I think all Boeing aircraft currently in production are RNP capable by default. I am saying however that I doubt 747s are actually flying such approaches. The type of airports where true (those of higher precision) RNP approaches are being used are not served by 747.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[downscc 1,327]

So? If all Boeings have RNP capability then why not the simulation? My preference is for the B737 because I get board cruising at altitude.The point I'm trying to make has something to do with RNP modelling: I've just spent all morning trying to get the KSMF FROGO6 DP to work for rwy34L/R takeoffs... "Maintain rwy hdg until 1500 then right turn heading 140 to intercept MYV R-154 to LIAMM." The ability to program ARINC legs for this is a tricky but possible, the SIDSTAR code as written can't without creating fixes for simulation, it changes heading instantly at 1500 and as a result doesn't intercept the radial until past LIAMM and ends up turning backtracking to the fix. All that yanking and banking is usually frowned upon.I'm new to the PMDG stuff, but so far I've noticed SIDSTAR procedural "bugs" that need tweaking for KLAS RNAV DPs, KLAS STARS (the two I've flown so far) and the KSMF DP, these are the three of the four total trips I've accumulated so far with this product. I am not putting down the SIDSTAR files (I really do appreciate they exist) but I am all for making some progress.This has nothing to do with B747s or any other aircraft type. I'd love to have RNP in the C-414 I fly but I can't afford it so I like to play with flight sim...Dan DownsKCRP

[michal 44]

I don't dispute that it would be extremely satisfying to see a simulated RNP approach executed flawlessly in this product - it would better even an autoland. ;)Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[michal 44]

I recalled this thread because just minutes ago I was reading a very interesting letter to the editor of Aviation Week & Space Technology whose author is a 767 pilot. This pilot describes how 12 years ago he and his copilot set up an approach to Washington National airport that in its layout very closely matches the existing new RNP approach at this airport. They flew this approach (in VFR conditions) only using the existing LNAV/VNAV functionality of that 767 and punching in all the required waypoints manually into the FMS. The airplane apparently flew this course very precisely both in ground track and altitude.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[downscc 1,327]

Innovation, great. The FAA has gone way overboard (my opinion) in their heavy restriction of aircrew and aircraft certification requirements for RNP. We'll never see it in general aviation except for Gulfstreams. Oops, off topic, sorry.My biggest gripe with the PMDG FMC is that it will not simulate RNP approaches because of one significant limitation: It cannot simulate radius-to-fix (RF) legs that are required for RNP equipment. This is not a requirement for current RNAV SIDs & STARs but the new IAS RNP procedures all seem to require the ability to follow a curved track from one point to the next with a defined radius (within 0.11nm at DCA). There's no practical way of programming that with the PMDG FMC since it is a basic track-to-fix (TF) box (with constraints that sometimes work). I suppose you could put unnamed fixes along the desired path and tweak it until you got the desired result; I've played with that, but the result isn't as hoped.I've looked at the LevelD stuff, which uses XML instead of text, but they don't seem to have a "better" solution.Microsoft's FS9 BGLCOMP compiler uses the ARINC legs required for SIDs and STARs but doesn't recognize the RF legs either.If PMDG were to update their FMC capability, they would be the leader in high fidelity flight managment simulation. In otherwords, a real innovator. That's be great!

[zubart 5]

Just a correction. Normal RNAV approach RNP is 0.3 not 3.0.Modeling RNP and ANP would be cool though.Floyd

[michal 44]

>require the ability to follow a curved track from one point to>the next with a defined radius (within 0.11nm at DCA). That may be a technicality required for real life equipment but we just want here to demo such RNP approach using whatever functionality already exists. Is PMDG's LNAV/VNAV good enough to excute such approach assuming we just want it to fly through all the waypoints and not worry about a radius for a moment?Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[Guest D17S]

Give it a try. Set up a STAR transiting into an IAP. That's all selectable from the APP/DEP pages. From TOD, just let it go. Within 25 miles, VNAV PATH will let you speed intervene (thrust>"SPD") while keeping you on path. So reduce speed and get the flaps and gear out on schedule. Now watch what happens. Once you are within range, the LOC and GS will annunciate, but don't select APP. Let Lnav and Vnav just keep on navin'. As Lnav turns the corner at the IP onto final, watch LOC. Lnav will keep you right on the localizer. Now watch the Vnav path scale in the ND. It will track glide slope exactly (don't forget to reset your altimeter to field elevation though). At 50 feet (or 20!), disco and land manually. At this point, all that is needed (in the model-or RL?) is for Lnav/Vnav approaches to allow a Land 3 mode and the corresponding Flare and Rollout functions. I imagine part of real world hold up is certifying GPS

[downscc 1,327]

>Is PMDG's LNAV/VNAV good enough to excute such approach assuming we just want it to fly through all the waypoints and not worry about a radius for a moment?I don't think so, at least for the DCA RNAV 19 RNP...; however, the good news is that I have already looked up all the fixes in the FAA 7350 LID reference, I've created the approach in xml for bglcomp and I've had some success modifying SIDSTAR txt files, so: I'll take the assignment this evening and keep notes for posting back here. My concern is that the arcs defined for the approach involve a change in heading of more than 90-deg, there will have to be some manipulation to come close to the desired tracks.I'll report back.