FMC Route Page During Preflight Prep

[Captain_al]

Here is what I was referring to Hardy:

On the Route Page during preflight of the CDU, if you enter a runway by either typing it out on the RTE page 1 or selecting the runway from DEP/ARR page (preferred method), and then going to RTE page 2 and selecting a WPT under the TO line, there will be a connection between the runway and the first waypoint and it will default to DIRECT under the VIA line.

If you go to RTE Page 2 first and put in a TO waypoint like ABC VOR, and then go to the DEP/ARR page (preferred) or go to Page 1 and type out the runway, the VIA line will show dashes (---) and there will be no connection between the runway and your first waypoint.

This is a cleaner method  if you are flying RH for radar vectors to ABC VOR/WPT and you don't want to see a direct line going from the runway to your first point. So you are vectored and then at some point ATC gives you Direct and you perform the modification.


In the PSX model, both ways give you Direct. I have seen the above scenario since 1988 in all FMC's and all models.

The reference is in the FCOM, Navigation, Preflight, Route Page and copied below for your reference.
Excerpt from 747-4 FCOM:

During preflight when entering a runway on RTE page 1 and entering a waypoint
in the TO column without first entering a VIA airway displays a DIRECT segment
on the first VIA line from the runway threshold. When a runway has not been
entered on RTE page 1, dashes display on the first VIA line.

What they don't say is that if you then go and enter a runway (No SID), it stays dashes...

[Hardy Heinlin]

Which PSX version are you using, Captain?

[Captain_al]

Version 10.105

[Hardy Heinlin]

OK, I see what you mean.

(And it should affect inactive, active, and modified routes.)

I need to know one more detail ...

Situation:
Route is empty
No runway is entered
Aircraft is at the gate

Action:
Enter runway XY
Enter waypoint ABC

Result:
The ND draws a line to ABC

Question:
On the real deck, where does this line start?
(A) At the gate where the aircraft is parked
(B) At the threshold of runway XY


Regards,

|-|ardy

[Captain_al]

B    At the threshold of Runway XY

[Hardy Heinlin]

Good. That keeps the logic consistent.

[Hardy Heinlin]

This trick has a side effect: It is impossible to program a direct-to when the aircraft is on the ground at an airport which is not in the database. Is this intentional?

Say, you are on a runway which is not in the database. You have waypoint ABC in the first leg. You can't get a direct line to ABC because on the ground the initial line can only start at an entered database runway.

[Hardy Heinlin]

In the real 744 FMC on the ground, when no runway is entered, and one waypoint ABC is entered, this ABC will be an anchor fix with "---" in the first LEGS course line.

What happens in the real 744 FMC on the ground, when you downselect and upselect ABC into LSK1? Will it remain an anchor fix, or will there be a direct-to line from the aircraft to ABC?


|-|

[Captain_al]

That is a good question, I do not know, I don't think I ever tried it so I don't want to guess, I can try it whenever I finally get to work again, whenever that will be with this pandemic.

[Captain_al]

Your comment on the runway not in the database sounds logical to me.

I don't think you would get a direct to line since there is no reference point. I have not dealt much with stuff not in the database, say coverage limitations to a region like in the 757 or airports not in the database...

[Hardy Heinlin]

Now I've modified my code according to the description in your first post of this thread. It works fine so far.

The modification will be in PSX version 10.106. I'll add some further new features to this version in the next days; I guess I can upload it next week.


Regards,

|-|ardy

[Captain_al]

Thank you Hardy, will be on the lookout for it...

[Hardy Heinlin]

The runway entry logic is now modified in PSX 10.106 (item 106.19):

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


|-|ardy

[Hardy Heinlin]

If you go to RTE Page 2 first and put in a TO waypoint like ABC VOR, and then go to the DEP/ARR page (preferred) or go to Page 1 and type out the runway, the VIA line will show dashes (---) and there will be no connection between the runway and your first waypoint.

Hi Al,

I just learned from an Atlas Air sim that getting those dashes actually requires two conditions. The absent runway entry is just one of the two conditions.

The second condition is this: The route has to be inactive when entering a first waypoint.

When you activate an inactive RTE that contains no runway but at least one waypoint, the dashes will remain. However, when you re-enter that waypoint in 1L on the LEGS (while still no runway exists), the dashes will disappear and a direct-to will occur.

In my current PSX version the direct-to will not occur in this case. I will modify it according to the Atlas sim behaviour.

In short words: During preflight when no runway is entered, the anchor waypoint can only be created in an inactive RTE, and after the RTE activation the anchor will remain as long as the pilot doesn't make an entry in 1L on the LEGS again. Any further 1L entry will create a direct-to, even if a runway is not entered yet.


Regards,

|-|ardy

[Will]

I'm not seeing this. Version 10.117.

Starting with a cold and dark cockpit, running the cockpit safety checklist, power provided by the APU, and IRSs aligned.

RTE1 is empty, no waypoints, nothing in either VIA or TO on RTE page 2. No runway on RTE page 1.

I enter a nearby VOR in LSK1R, and the VIA populates with DIRECT. 

What am I missing?

[Hardy Heinlin]

In 10.117 you first need to activate the RTE, then re-enter your first waypoint, then it will become an anchor.

Just ignore it; version 10.118 will be different anyway.


|-|ardy

[Will]

WILCO, thanks. :-)

[Hardy Heinlin]

The new on-ground direct-to logic is now available in PSX 10.118:

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


|-|ardy

[Captain_al]

When you activate an inactive RTE that contains no runway but at least one waypoint, the dashes will remain. However, when you re-enter that waypoint in 1L on the LEGS (while still no runway exists), the dashes will disappear and a direct-to will occur.

Thanks Hardy, that makes sense. I was most familiar with the first condition, which I saw frequently in training, which caused me to initiate the post and question...

[Will]

Can you get this state (the dashes in 1L, and no magenta line from the runway to the first waypoint) when you are using a company route that has been uplinked? Or only when you manually enter the route?