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ESzczesniak

Flying JNU5 SID in NGX?

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I've been putting together a circuit in Alaska mirroring some Alaskan Airlines routes (PAJN-PASI-PAKT-PAJN).  It looks like ASA flies a proprietary SID (RODMN1) out of PAJN, so the next best thing is the JNU5 SID I can find on airnav.com (http://155.178.201.160/d-tpp/1613/01191JUNEAU.PDF).

 

So, my question is how would the computers be setup to fly this SID?  Effectively, it's a quick turn after takeoff from either runway to intercept the backcourse localizer to RWY 8.  The backcourse is my dilemma.  The NG's don't seem to be particularly set up to fly a back course.  I can fly the back course manually (I usually fly a departure up to about 10k by hand anyway), but in the sim at least I don't get any localizer signals on the back course until about 3,000' AFE.  

 

How would the guys do it in real life?  Would they fly LNAV backed up by raw data on the PNF side?  Should the backcourse signal (I know it's not really a separate signal) show up earlier?  Is there a way to get the NG to understand backcourse?  

 

Thanks for any input!

 

Eric Szczesniak

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So, my question is how would the computers be setup to fly this SID?

 

Select it in the DEP page. Fly raw data to the LNAV track (likely at the NDB - I haven't looked at it though).

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Select it in the DEP page. Fly raw data to the LNAV track (likely at the NDB - I haven't looked at it though).

 

That's where I'm struggling a bit.  In the sim at least (I'm suspecting real life may be different), I don't get raw data until about 3,000' AFE.  It's a LOC backcourse and I get neither the diamond on the PFD or a LOC bar if I'm in APP in the EFIS.  I have selected the SID in the DEP page and can fly LNAV, but by the procedure should be raw data...but 3,000' AFE is pretty late to start flying the DP in the terrain of this area.  I'm suspecting in the sim at least, I'm going to need to do LNAV backed up by raw data (and maybe FIX pages for visual backup on ND). 

 

There is an option direct to an NDB, so I can certainly of course put ADF1 on the the ND and fly direct that as well.

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Why fly raw data? You're right, the NG doesn't like back course procedures... but if the procedure is coded and selectable in the box, just fly it in map mode and LNAV. There'd be no reason to fly it raw data unless your FMCs were MELd or something.

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RWY 08: HDG SEL for takeoff and fly the departure route visually until established on the 279* track and ENGAGE LNAV.

 

RWY 26: Take-off in HDG SEL. Engage LNAV at 400’

 

For most SIDs visual climb up to 1000' is required due to obstacles in the area. DER must be visible and ceiling 500’+.

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For RWY08 in VMC you can go to the NDB, in IMC you can go hdg 279.

 

This hdg will be part of the lnav routing when you select this SID in the FMC

 

It might give direct to the NDB, but that is in IMC not allowed.

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Vernon, this procedure requires VFR weather anyway, so splitting hairs about legality isn't necessary.

 

That's why we use the RODMN and the GLAZZ instead.

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Thank you all for the replies.  I guess I shouldn't have been trying to make things so complicated and just been using LNAV.  For some reason I've had an aversion to LNAV when the procedures have described VOR/NDB/etc.  I think I viewed it as less precise to use LNAV in those cases, but that probably doesn't make much since given RNP approaches, etc. 

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Eric, it was a great question. That's a kind of unique procedure (a lot of the SE Alaska procedures are, that's what makes them fun). The fact that someone can use the simulator to try out these procedures and identify the "gotchas" or points of confusion that would arise in real life as well really says something about just how good this simulation is. I mean all of it put together - FSX/P3D, the ORBX scenery, the NGX... it's a level of accuracy that the geek in me marvels at ;-).

 

You are right that you could also just fly a right turn direct to the CGL NDB, because the procedure says you have to maintain VMC to Coughlin island anyway.

 

As far as LNAV accuracy, the reality is that it flies more accurately and more smoothly than when coupled to ground-based navaids, because it knows the entire path to fly and can lead turns etc, vs just reacting to needle movement. Plus, a lot of navaids in various parts of the world can, well, be a little sketchy. At my previous job, we did lots of non-precision approaches into small Mexican airports. Legally, before we got RNAV approach authorization, we had to fly those procedures on conventional nav. Those were some sketchy navaids. The plane had all the current RNAV approaches in the box. Lots of pilots flew those approaches in LNAV, because legalities aside, the accuracy of the DME arc to the non-precision approach was far better than using VORs.

 

The RNP procedures lower the workload of all this in a big way. If you can successfully operate up there with the public procedures, the proprietary ones are easy.

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