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News: The latest PSX update (version 10.38 from 10 July 2018) is available at: http://aerowinx.com/board/index.php?topic=4191.0

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1
Hangar 7 / Re: FMC offset route
« Last post by Markus Vitzethum on Mon, 16 Jul 2018 12:04 »
> The direct-to obviously destroys the SID

Has anybody (ever) checked what's happening on the route page when choosing a direct-to on a SID? Does it keep the SID identifier or does it say DIRECT on 1L?

The question "what happens when you choose direct-to?" with two possibilities is probably the same, just in different words:
1) does it pull the direct-to-fix freshly out of the waypoint/VOR/NDB/... database inside the box?
2) does it just up-select the existing fix from the LEGS page?

(Keeping the route page should also answer when the offset prompt appears.)

There is one difference with offsets on STARs - it's well documented in CBTs that route offsets will end at the last route waypoint and the airplane will keep its present heading and say END OF OFFSET. I learn this from this random 767 CBT from youtube:
https://youtu.be/-5zYseI6ddk?t=588

Markus
2
Hangar 7 / Re: FMC offset route
« Last post by emerydc8 on Mon, 16 Jul 2018 10:22 »
I'll ask, but I doubt he will remember. What happens is you will eventually get vectored off the STAR for the approach and at that point you are just going to extend from the CF or FF and the STAR is flushed out.
3
Hangar 7 / Re: FMC VOR Auto/Route Tuning Behavior
« Last post by John H Watson on Mon, 16 Jul 2018 09:35 »
Quote
I just meant to say that if channels 1 and 4 are different, which is usually the case,

I keep forgetting that there is only one FMC doing the tuning, so you would think the FMC would pick different stations.

This closest station logic is a confusion factor, though...

Procedure and Autotuned Stations






 

4
Hangar 7 / Re: FMC VOR Auto/Route Tuning Behavior
« Last post by Hardy Heinlin on Mon, 16 Jul 2018 08:24 »
I just meant to say that if channels 1 and 4 are different, which is usually the case, and if 1 and 4 are displayed on the ND, then 1 and 4 cannot be co-located with the same VOR. No VOR station in the world has two co-located DMEs.

Quote
Does the statement "only one M, P, R" refer to the FMC's decision to use only one?

My interpretation: Of the two radios on the NAV RAD page, just one is M, P, or R tuned. M is the pilot's decision, P and R are the FMC's decision. I guess it doesn't matter whose decision it is.


|-|ardy
5
Hangar 7 / Re: FMC VOR Auto/Route Tuning Behavior
« Last post by John H Watson on Mon, 16 Jul 2018 07:52 »
Quote
Isn't this 34-61-00 flow diagram just about DME channels?

The text in the boxes does include a reference to (CDU) "displayed frequencies" (either DME channel 1 or 4). Since the Nav Rad page doesn't show actual (UHF) DME frequencies*, then what is shown is the co-located or paired (VHF) VOR frequencies. DME and VOR frequencies are paired (even if the station is a DME-only station). Manually tuning a VOR station will lock in a specific DME paired frequency (even if the VOR station is VOR-only and there is no usable DME information).

I think I misunderstood the expression "simultaneous displays". I earlier thought they meant identical displays.  I wonder, though, if there are some unusual situations (due to say a temporary power loss) where one DME interrogator might power up later than the other with the aircraft in a different position... and the tuning algorithm begin at a different time causing a different solution... which may lead to identical displayed VOR frequencies (from channels 1 and 4).

I'm having problems understanding the flow chart. Does the statement "only one M, P, R" refer to the FMC's decision to use only one? Or there is only one of these stations available?

Quote
When the left display uses channel 1, and the right display uses channel 4, as indicated in the text, can't we assume that channel 1 (odd number) is different to channel 4 (even number)?

Sounds logical.

This stuff gets complicated because I've read that the stations being used for navigation are not always the stations shown. e.g. A manually tuned VOR-DME station will not stop the FMC using two other separate DMEs.

*DME frequencies are in the  960Mhz - 1215 MHz band. VOR frequencies are in the 108~117.95MHz frequency band.

6
Hangar 7 / Re: FMC offset route
« Last post by Hardy Heinlin on Mon, 16 Jul 2018 07:49 »
And where does it end?
7
Hangar 7 / Re: FMC offset route
« Last post by emerydc8 on Mon, 16 Jul 2018 07:45 »
Just got an email from my friend who confirms that they get offsets on the STAR going into PVG all the time too.
8
Hangar 7 / Re: FMC offset route
« Last post by emerydc8 on Mon, 16 Jul 2018 01:24 »
I'll check that. I think it works on arrivals too, but we'll see.

Jon
9
Hangar 7 / Re: GPS Blocking
« Last post by emerydc8 on Mon, 16 Jul 2018 01:20 »
Thanks for the input. I finally found it buried deep in a table in our Ops Specs. We can do RNAV-1 with just DME/DME updates. Our 744s can too.

10
Hangar 7 / Re: GPS Blocking
« Last post by IefCooreman on Sun, 15 Jul 2018 23:19 »
The whole idea of PBN vs RNAV development is the inclusion of "onboard performance monitoring". In general words:

* P-RNAV was developped for a "monitored environment", like radar supported arrival and departure areas. It basically certifies: "accurate up to a 1 mile for 95% of the time, and for 5% inaccuracy ATC has a radar to cover/monitor you".

* PBN generates a lot more possibilities to cover for "unmonitored" navigation. RNP 1 is like P-RNAV, but for "unmonitored" terminal ares. It is developed for the transition from en-route airspace to terminal airspace with NO or limited radar coverage.

Quick stroll through our manuals on the topic of RNP1:
* RNP 1 does require GNSS coverage, and usually direct pilot-controller communication. Loss of FDE level is restricted to 5 minutes (if more, flightplan should be revised).
* Pilots must realize that RAIM or GPS navigation altogether may be lost while airborne which may require reversion to an alternate means of navigation. Therefore, pilots shall assess their capability to navigate (potentially to an alternate destination) in case of failure of GPS navigation.
* Pilots must notify ATC of any loss of the _RNP_ capability (integrity alerts or loss of navigation), together with the proposed course of action.

The way I understand the 7 pages in our manuals: inform ATC and find out if you can revert to other procedures (probably based on radar, radar headings, ground based navaids,... read back to P-RNAV or B-RNAV). If there is no radar coverage, and in certain situations it might lead to a diversion as the RNP1 is probably used to transition to an RNP approach (which wil need GPS...).

Good luck :-)
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