NG FMC: Examples of RF legs

[Hardy Heinlin]

Hi all,

here's a situ file of an RNAV approach into KGPI. Right-click on this link, then select "Save Link As...", and save it to your Aerowinx/Situations subfolder.

The situ file will appear on your list on Instructor > Situation > Load under the name:

03 Approach 100 - Glacier Park - RNAV20.situ

If you are copying the file while PSX is running, click the ESC key twice to refresh the file list.

RF legs are the legs to BUTSE, to KILLY, then from RAPOY to TAGUY, then to DOTRE and to DEBRE:






Regards,

|-|ardy

[MalcolmT]

Hi Hardy

Using Windows 10 here and the only option on right-clicking is "Save Target as ...".
Furthermore, using this, it saves the file as an HTML file type, and you cannot change it.  Obviously, this file type will not load in PSX.
Do you have a suggestion please?

Thanks
Malcolm

[martin]

That must be a browser thing; Firefox under Win10 does show "Save Link As...".
Make sure to right-click on the words "this link" (in blue) in Hardy's post. (Me, I tried the image first, to no avail  )

Hope this helps.

Cheers,
Martin

[MalcolmT]

Hi all

Solved, but something other Windows 10 users may need to be aware of.  It probably is a browser issue (Microsoft Edge here).

Anyway, I downloaded the file as a HTML again, and simply renamed the file extension to .situ and all is good!

Thanks for the input.

Malcolm

[Hardy Heinlin]

You may click the link with the left button. A text page will open (it's the situ file). Then, on the browser menu, click "Save Page As...".


|-|ardy

[Will]

https://www.dropbox.com/s/rue6hy5j0ybm0ec/WJC%20Custom%2008%20Kathmandu%20RNAV%2002.situ?dl=0

At the above link, you'll find a situ with the aircraft set up for the Kathmandu RNAV (RNP) RWY 02. The situ starts just outside of DANFE. The first RF leg is just after DANFE, from KT540 to KT538. Other RF legs are ahead of DOVAN (visible in the picture above) and then KT522 to KT520 (also in the picture, approaching the runway). There are some RF legs on the missed approach as well.

(If someone can verify that my link works, I'd appreciate it. Thanks!)

[andrej]

Will, the links works well here.

[Will]

Thank you!

[MalcolmT]

Ditto.

Thanks Will.

[Hardy Heinlin]

Note that Will's situ uses real-world weather. To be sure your flight deck has the latest QNH, press the N key after loading this situ. The correct QNH is essential on this approach :-)


|-|ardy

[Will]

https://www.dropbox.com/s/3kzhwyzt0mjla5m/WJC%20Custom%2010%20Quito%20RNAV%2018.situ?dl=0

Here is another good one.

Start by giving yourself a speed restriction, or else you'll crash. I'd recommend setting 250 kts in the FMC at QM040; don't speed intervene on the MCP, as that will just make more work for you. (I initially flew this without a speed restriction and it was Mr. Toad's Wild Ride, with the flaps coming in at the upper limit speed each step along the way. It was completely nuts.)

Remember to change from STD to the current altimeter setting when passing through the transition altitude of FL180. Also, make sure to dial in the missed approach altitude of FL190 after the FMC has switched to on-approach logic (and if you don't want to look at the FMC to see exactly when this happens, you could just wait until you set flaps 1, thanks to the NG FMC).

You'll note that Rwy 18 has an ILS that the FMC auto-tunes, so you can compare the VNAV descent with the glideslope on the ILS. They match up really quite well.

Also, my virtual FO chose AUTOBRAKES 2, probably because a 13,000 foot runway seemed like a generous amount of pavement, but maybe that wasn't really the best choice when the airport elevation is almost 8000 feet.

The situ begins just after crossing UTPEK northbound at FL190, initiating a descent to FL180. You are cleared for the Quito RNAV (RNP) Y Rwy 18 approach. Buckle your seatbelts; this one goes fast.

[Hardy Heinlin]

... my virtual FO chose AUTOBRAKES 2, probably because a 13,000 foot runway seemed like a generous amount of pavement, but maybe that wasn't really the best choice when the airport elevation is almost 8000 feet.

I just modified the PNF's brain in PSX 10.97 (item 97.03):

http://aerowinx.com/board/index.php?topic=4191.0


|-|

[Britjet]

Personally - I would think that Autobrakes 2 would be ideal (and don't override it) for a 13,000ft runway. Otherwise you would probably get a brake overheat on landing. But the overall concept for the PNF is a sound one..

Peter.

[Will]

https://www.dropbox.com/s/dlumcza7vpnyutb/WJC%20Custom%2011.3%20Madeira%20RNP%20Z%20Rwy%2005.situ?dl=0

Here is one final (from me, anyway) example of an approach with RF legs, the RNAV (RNP) Z Rwy 5 into Madiera. Like the approach into Kathmandu, this one has RF legs on both the approach and missed approach sections. The situ starts just prior to MA526.

This one is notable for the very late turn onto final. Have fun, and don't forget to set the MP altitude to 3000.

[Jeroen Hoppenbrouwers]

Is that peculiar Worldflight video available somewhere...?

[cagarini]

@Will 

A BIG THANK YOU for the LPMA 05 RNAV approach !

Great !!!!!!!!!!!!!

[cavaricooper]

Will-

I appreciate your efforts as well. 

I was however wondering if you had now noticed a tendency for LNAV to fly the RF curved segments slightly segmentedly?  For me, especially during the LPMA 05, there was a distinct and repeated behavior of correction, to over correction; then overshoot of flight path and re-correction from the other side.  As the radius of turn got tighter, the behavior was more pronounced.  When the NG FMC modification was brand new and rolling out to the fleet, I wonder if Boeing wrote more smoothing into their LNAV software to eliminate this tendency?  I wonder if some of our RW pilots remember this transition period with just this sort of AFDS behavior?

As far as your SITUs, they are quite wonderful for exploring the nuances of this addition to PSX.  I typically reset the MCP to the start/current ALT gate and usually SPD INTV so I can control the Flap Schedule.  This keeps me more in the loop as I step down and slow down in L/VNAV and allows me the security of interaction with the A/T AFDS.  I would love to know if IRL this is done, or it is SOP to just monitor the speeds and altitudes on the LEGS page and leave the ALT at MINS+?

For me the small amount of manual interaction gives me some amount of greater SA and delays the overwhelming sense of getting behind the aeroplane .

Again, thank-you!

C

[Alec246]

Happened to me as well. It seems the AP is not calculating a proper constant angle turn to maintain the flightpatch within the RF Leg limits. The airplane overshoots and then go chasing it the other way around. Since I have no real experience with any of this, I don't know how the real 747 should behave in this situation

[Jeroen Hoppenbrouwers]

Any input on what the winds were during your test flights?

[Hardy Heinlin]

It seems the AP is not calculating a proper constant angle turn to maintain the flightpatch ...

You mean the transition phase. Not the entire RF leg (I'd say the long part between the transitions is perfect, like on a DME arc).

This is not trivial, gentlemen. In the transition phase to the next leg the bank angle cannot change abruptly. Unlike a small fighter jet, the 747 has a great inertia. It smoothly changes its bank angle, and therefore the actual transition curve at the waypoint is not an arc but an exponential curve. Developing a perfect control system, including wind influence and performance variations, is ... almost "rocket science". The Boeing engineers are better than me.


|-|ardy