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SEATAC

Transition help please

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I'm sure that one of you knowledgeable guys can help out with this.

I load a flight plan into my FMC and fly most of the way, on the descent ATC verifies the runway to use. In AivlaSoft EFB I select the approach, but I never quite know which transition to use because I don't really understand the differences between them.

 

As an example, on a flight from Naples (LIRN) to Frankfurt (EDDF) ATC tells me to use ILS RW 25L so I select the ILS 25L approach but then my transition choices are as follows:

CHA (SouthEast)

KE25S (NorhtEast)

MTR (North)

PS25S (SouthEast)

RO25S (NorthWest)

UN25S (West)

 

I am approaching the airport from the South East as my last 2 headings are 301 for 77.5 NM and then 288 for 31.8 NM.

What would be the determining factor in which one I select?

What do the directions indicate (SouthEast, North, etc.)?  Is it what direction I am approaching the airport from? 

I usually blindly choose one but sometimes it results in a long and convoluted transition. If anyone could explain this I would be very grateful.

 

Thanks in advance.

 

Edited by SEATAC

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Hey Richard,

 

forgive me me if this makes little sense, but I'm seriously tired after the week from hell. (And with two more weeks to come, yay!)

 

From my point of view, generally your transition point will follow your flight plan. So using this quick flight plan I've grabbed from the web.

 

TEA UL995 PEPAG UN851 ROLSA Z162 ZUE T163 PSA

 

 

 

From your selection above, the correct choice would be PS25S. That will use the PS25S STAR beginning at the PSA waypoint. 

 

hope this helps. 

 

Jess B

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Thanks Jess. My route also had PSA as the final waypoint before EDDF.  But what is the logic behind that selection other than both the waypoint and the transition beginning with 'PS'?

 

My entire routing is this:

TEA ERIKA KASTU ARBIP AMSED LOBSI VIC ALESE BZO OGEPI BRENO INN NORIN KOGOL KONIN MAH BESNI ERNAS TALAL ERMEL PSA

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I'm going to assume you are not using instructions from ATC. If you are, the vectors to the approach will be given to you as part of your approach clearance. This requires you to simply follow those instructions.

 

Otherwise: As described by @Jess-b, the transition is often the waypoint or fix shared by both the end of your ROUTE and the beginning of a STAR or the end of a STAR and the beginning of an APPROACH.

 

Unfortunately, this is not always the case.

 

Your best bet is to study the available plates (you do have a set for each airport??) and choose the STAR that makes the most sense based on your direction of approach to the airport area and the wind direction or landing runway described in the ATIS. This process is usually done in the last thirty to fifty miles of your descent dependent on radio reception range (you do have to hear the ATIS). Next, choose the transition (if there is one) that gives the most economical routing between your route and the STAR.

 

The histrionics and screw-ball routing that the FMC sometimes hands you can be checked using the FMC's "STEP MODE". Often the final waypoint in a route is a long way from the airport (or even a point on the airport itself) requiring you to add or subtract waypoints to/from your route to match up with a published STAR and its TRANSITION.

 

The STAR and TRANSITION are important in that there is likely to be altitude and speed restrictions contained that assist you in getting to the IAP for your landing runway.

 

If all else fails - hand the job over to the highly paid co-pilot sitting on your right :whis:

 

Seriously; If not using ATC, I use the 'Pause" feature in my sim to give me the time that would normally be covered by additional crew. 

 

Edited by Quickmarch
Correct syntax

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Here's another $0.02 worth on the list of Transitions in the OP...

 

CHA (SouthEast)

This refers to an entry point over the CHA (Charlie) VOR (115.50 MHz), which looks to be about 15 NM SE of EDDF

 

KE25S (NorhtEast)

I find this on a Jepp RNAV TRANSITION chart for EDDF (download from here... https://yinlei.org/x-plane10/jep/EDDF.pdf ), also listed as KERAX 25N, a reference to the KERAX intersection, which is 13.3 NM bearing 072 from the GED (Gedern) VOR.  The VOR is about 25 NM NE of EDDF.  Not sure where KE25S is exactly but it's listed (not shown) in text on that chart.

 

MTR (North)

This refers to an entry point over the MTR (METRO) VOR (110.00 MHz), which looks to be about 10 or 12 NM NNE of EDDF

 

PS25S (SouthEast)

I find this on a Jepp RNAV TRANSITION chart for EDDF (download from here... https://yinlei.org/x-plane10/jep/EDDF.pdf ), also listed as PSA 25S, a reference to the PSA (Spessart) NDB (370 KHz).  The NDB is about 20 NM ESE of EDDF.  Not sure where PS25S is exactly but it's listed (not shown) in text on that chart.

 

Ditto the above for the two waypoints below.  Both are included in another plate of the download source listed above.

RO25S (NorthWest)
UN25S (West)

 

John

 

EDIT:

RO is ROLIS, an Intersection NW of EDDF.

 

UN is UNOKO, also an Intersection NW of EDDF.

 

Another EDIT:

 

What would be the determining factor in which one I select?


What do the directions indicate (SouthEast, North, etc.)?  Is it what direction I am approaching the airport from?

 

 

Yes, it's exactly that.

 

I usually blindly choose one but sometimes it results in a long and convoluted transition. If anyone could explain this I would be very grateful.

 

Even it you choose the best one you may still have a long and convoluted approach.  

 

If there's a choice in the FMS for "Vectors" (the Garmin GPS does have that option; I've never used an FMS), you might get a little better approach.  That typically means you'll get ATC vectors to the FAF and is usually a pretty direct approach, not unlike what you get with raw MS ATC unless they decide to favor you with the dreaded sawtooth approach or bat you between two frequencies like a shuttlecock.

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Thank you very much everyone.  That really helps me out.  Using the very useful and informative information you have provided I went back to that flight plan and first inserted the arrival. I chose PSA1B and then I inserted the approach of CHA (SouthEast) and took a look at the routing overlaid on the plate and it made a lot of sense and looked pretty good.  When I chose the PS25S it looked more like a switchback for driving up a mountain.  :) Now I have a better understanding of what they all mean so I will do some more experimenting now that I'm getting the hang of it! Here's what she looks like with the PSA1B arrival and CHA transition.

eddfapproach.jpg

 

Edited by SEATAC

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4 hours ago, allardjd said:

That looks like a pretty straight forward way in.

 

John

 

Yeah, wouldn't want to upset the neighbors.^_^

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