Vector SID- Direct to First Waypoint

[emerydc8]

Hi Hardy,

Just got back from the sim and uploaded this video. I think it may answer some of our questions on this. I'll let you evaluate what logic it is using to come up with what you will see in the video. Cheers.

https://youtu.be/j9G4RUo3ahA

Jon

[Hardy Heinlin]

Hi Jon,

fine, fine :-) Thank you!

OK, my conclusion now ...

• Before VECTORS is active, the line to VTU is fixed.

• When VECTORS is active, the line to VTU is adjusting itself so that it can anytime serve as a direct-to.

• When VECTORS is sequenced, the line to VTU stops moving and starts with a turn segment.


I think the same would happen with the line to CHATY on my photo: Before VECTORS is active, the line to CHATY is fixed behind the aircraft. When VECTORS is active, the line to CHATY jumps over to the aircraft's area and is adjusting itself so that it can anytime serve as a direct-to. -- Etc.


Regards,

|-|ardy

[emerydc8]

That sounds right. I guess when VECTORS is active, the magenta line constantly recalculates a direct-to and the starting point of the turn sits a mile in front of the nose, because at any given time it would take that distance to complete the turn direct to the fix (VTU)?

[Jeroen Hoppenbrouwers]

It's probably only a rough approximation of the course. The turn radius obviously depends on speed, and I bet nobody wanted to invest in a routine to also constantly calculate the turn required. Just a reasonable, and intuitively correct, throw at it. After all, it is not really a magenta line "aircraft is going to fly this". It is a predicted possibility only. It is not connected to the nose of the aircraft. It should not be a magenta line at all, but I don't know what else would be really better. Dashed magenta? No -- that would conflict with the preset HDG SEL dashed line. Same kind as in PLAN or pre-EXEC mode, dashed grey/white? No -- that would suggest a pending LEGS mod. Etc.

When LNAV finally latches on and computes the real turn, I bet it uses a brand-new direct-to calculation exactly like what it would have done when you transfer the fix to L1 and EXEC it.


Hoppie

[Hardy Heinlin]

The turn radius is just a function of groundspeed. Computed in one nanosecond. Easy. You also get this when a direct-to is in the MOD RTE before EXECution. The FMC is doing this all the time. In this case it's even doing this only at 1 Hz, as one can see on the ND in the video. Also the VECTORS line is not smoothly following the aircraft nose; it jumps every second. In PSX the VECTORS motion is smooth. I need to make it worse to get the real look-and-feel :-)


|-|ardy

[Jeroen Hoppenbrouwers]

Yes, easy for YOU, but that FMC originally had a 68000 CPU at 1 MHz I believe...   :-)

[Hardy Heinlin]

In PSX there is, for example, an open-end course to CI26R after VECTORS on the ILS26R approach with the BAN3W transition at LFPG.

This is because the nav database includes a defined course to intercept CI26R.

The reason why there is no such line in some other VECTORS scenarios, e.g. in vectors SIDs at YSSY and KLAX, is because the nav database contains no defined courses after those vectors.

I assume, if a course is not defined, the course will be dynamic as shown in Jon's video. This means, on that Paris ILS26R approach you won't see the line to CI26R moving; it will stay as defined.

Does anybody disagree with my theory?

So what I have to do is add dynamic lines to those post-vectors waypoints which don't have a database defined course, instead of showing no line at all.


Regards,

|-|ardy

[Hardy Heinlin]

I'm developing a new rule regarding ...

... the dashed ---° leg line title on the LEGS page after VECTORS; it can appear or not appear.
... the magenta line on the ND after VECTORS; it can be hidden, or visible and static, or visible and dynamic.

To get a rule that agrees with Peter's and Jon's videos in the big sim, I suggest this:

IF the fix after VECTORS is within 100 nm of the previous fix THEN

     ---° will not appear
     If a database CRS is set, then the ND line is visible and static;
     else the ND line is visible and dynamic.

ELSE

     If a database CRS is set, then the ND line is visible and static, and ---° will not appear;
     else the ND line is hidden, and ---° will appear.

END


Regards,

|-|ardy

[Hardy Heinlin]

Good evening,

I think if a VECTORS leg is not based on a heading but based on a radial from a fix, then the magenta line on the ND should not disconnect from the previous leg; i.e. it should not float with the aircraft position.

Example -- FAOR ILS Y 03L, missed approach ends with radial based VECTORS:

http://www.caa.co.za/Aeronautical%20Charts/O.R.%20Tambo%20INTL%20-%20FAOR/FAOR_ILS%20Y%20RWY%2003L_ILS-02.pdf

As usual, in this case, the line title on the LEGS page will not read 220°HDG.

But, in this case, the line title on the LEGS page should not read 220°TRK either; it should just read 220° without a suffix, because this is neither a floating heading nor a floating track, but a normal fixed radial.

Does anybody disagree?



Example -- ZMUB ILS 14, missed approach ends with heading based VECTORS:

http://uvairlines.com/admin/resources/charts/ZMUB.pdf

This will read 310°HDG and the line will float with the aircraft.



Regards,

|-|ardy

[Britjet]

I think that sounds right. I'm pretty sure you are right about the floating heading-based-vectors.
Peter.

[emerydc8]

Hi Hardy,

I probably won't have access to a 744 sim for a while, but I will have access to Boeing's 767 sim in MIA later this month. Presuming it uses the same logic, I'll need to see if I can find some airports (SIDs) within the sim database where I can try some of your theories. I am told that their sim has limited airports. It doesn't even have SFO, so we are using PDX and SEA for training.

Jon

[Hardy Heinlin]

All new vectors features are now implemented in PSX 10.1.1 beta 10:

http://aerowinx.com/board/index.php?topic=4020.0


Cheers,

|-|ardy

[emerydc8]

Thanks, Hardy.

Jon

[emerydc8]

I had to put down my 767 material for a few hours to try the latest PSX revision. Here's a demo I just did of the VECTOR SID feature. Thanks for making the corrections to this, Hardy.

Jon

https://youtu.be/KnmC65efxpI

[jtsjc1]

Jon thanks for the video its good to see how this feature works. This Hardy guy is pretty good!

[emerydc8]

FYI,

Just tried this on the B767-300ER with the Pegasus FMS out of KIAH on the BNDTO FIVE Departure (26L) and it behaved as expected. The vectors condition was removed and the first direct-to waypoint (SHAAK) moved into 1L upon selecting HDG SEL. It would not do this until reaching the conditional waypoint (600') when VECTORS became active.

Also, I can't remember if (how) this was ever resolved on the forum, but with regard to using HDG SEL on the ground, prior to takeoff, we were given a takeoff clearance to fly the runway heading (267), so we selected HDG SEL as we spooled the engines up. This resulted in TOGA being replaced by HDG SEL and LNAV still remaining armed until 50'. Then LNAV went active.

Jon

[EDIT]: Resolved exactly one year ago. Thanks. http://aerowinx.com/board/index.php?topic=3598.msg37024#msg37024

[Hardy Heinlin]

(Last post above is from 24 May 2017. -- Now it's 29 December 2018.)


Good evening,

could it be that this Vectors-HDG-SEL automation is a feature of the 744 NG FMC and maybe an option in the legacy 744 FMC?

As far as I recall, it worked at Atlas Air and British Airways.

I was just told that it doesn't work on 4X-ICC (a 744 combi) when going direct to BAYYS on the JFK SID.


Regards,

|-|ardy

[emerydc8]

If I recall correctly, both Peter and I discovered that if there was a discon after the DIRECT-TO waypoint (e.g., nothing after BAYYS), the VECTORS condition will not be deleted by pushing HDG SEL. Also, looking at the KENNEDY 5 departure,  BAYYS departures are to expect vectors to BDR VOR or BDR R054. If BDR was at line 2, below VECTORS, and BAYYS was at line 3, it would be be BDR that would appear at 1L when HDG SEL was pushed -- not BAYYS.

[Hardy Heinlin]

That makes sense ...