FMC - Track Waypoints

[ksp0011 1]

Hi all,

I'm really loving flying the new -400 on P3dv4 but I'm having a problem with one function of the FMC. Before I explain, I have done the tutorial, read the FCOM and searched the forums and known issues list but can't find the answer. If it is there and I have missed it, I apologise.

The problem I am having is with "Manually Entered Along-Track Waypoints" as described on page 11.31.17 of the FCOM. I am currently doing short flights out of Moses Lake, and if I enter one relative to a fix, such as UPBOB using the format UPBOB/-10 it works. If I do the same thing relative to a navaid such as GEG or MLP using the format shown in the FCOM as GEG/-10 or MLP/10 and line select above or below the respective LEGS entry, I get the FMC message "Invalid Entry" and it won't accept it.

Does anyone else have this problem or am I doing something wrong? I am running the latest -400 update and P3Dv4 is at version 4.1

Many thanks

 

[downscc 1,327]

You should be able to enter ABC/-10 at the line containing the waypoint ABC and ABC will be pushed down and ABC01 will take its place 10 nm before ABC.  You should be able to enter ABC/10 on the line below ABC and an ABC02 will be inserted 10 nm after ABC.  Is the latter the case that is giving you invalid entry message or both cases?

[thibodba57 462]

I’m sure it’s not the issue but just to be thorough.  There are no fixes that are within 10NM of GEG or MLP?  For instance if fix ABCDE is 8NM prior to GEG and you try to do GEG/-10 you will get an invalid entry.

[ksp0011 1]

Dan. I can confirm that is what I have been trying and it gives me an error when I use a waypoint that is a navaid (i.e. one with a three letter descriptor such as GEG or MLP). I line select either the line with the waypoint or the one after depending on whether I want it before or after and it always comes back with 'Invalid Entry'. Five letter waypoints are fine. And to answer's Brian's question, I made sure there was at least fifty miles around each waypoint as I can imagine that would throw an error.

Perhaps you could both give it a try and see if all have same issue or if it is a quirk of mine?

[downscc 1,327]

I just happen to be approach DNV departing KSDF so i just entered DNV/20 at the line that contained DNV and it entered a DNV01 on the next line 20 nm later.  I was wrong, DNV/20 is not entered on the line below, but at DNV line and the FMS makes the adjustment.

[ksp0011 1]

Just been doing circuits at KMWH again getting a feel for the aircraft and noticed your post.

Dan, you are correct it is line select the waypoint you are creating a track waypoint for - so in my case for GEG, you would always select GEG.

So whilst on the downwind, I created a RTE2 plan from KMWH to KPAE with direct waypoints of MWH, GEG, SEA and PAE. When I entered a SEA/-20 or SEA/20 it worked and I ended up with SEA51 and SEA52 (as they were RTE2 psuedo waypoints. Flushed with success, I tried to enter one as GEG/20 and it failed. Then no matter what I tried to add it came up as invalid entry. Even if i deleted SEA51 and SEA52 it still would then not allow me to enter a track waypoint relative to SEA.

Back on the ground, I have been playing around some more and have the following initial findings:

i) it will not accept a track waypoint relative to the first fix in your route. i.e. if i enter SEA as my first waypoint and PAE as the second, it will not allow a SEA/10.

ii) it does not seem to like MWH, GEG or MLP for any reason.

iii) once you get the 'invalid entry' message it will not work with any waypoints until you reset the route on the init ref page.

If anyone fancies seeing if they get similar results, please let me know. When I get a chance, i will try a different location in the world in case there is something wrong with the database although I am not quite sure how that could affect it (I am using the default).

[downscc 1,327]

I don't think SEA and PAE are more than 10 nm apart....remember, given a segment from AAA to BBB and you want to create a waypoint 10 nm beyond AAA it will be along the AAA to BBB track and that BBB needs to be further than 10 nm.  You are literally creating an along track waypoint. I'm not sure I am following you or what it is that you are trying to accomplish.

[ksp0011 1]

I've played around some more and found out the cause of my problems.

If I want to enter a track waypoint for a navaid (such as GEG), I have to line select the appropriate entry on the LEGS page to bring the three letter name down to the scratchpad and then type /-10 or /10 (or whatever distance I fancy) as appropriate before line selecting the entry again. For a fix, i.e. I can either line select it to bring it down to the scratchpad and do as above, or alternatively I can just completely type in the whole fix with the /-10 using the keypad before then selecting the relevant LSK.

Now I have no idea how the real FMC behaves. The FCOM doesn't seem to imply that you should line select the waypoint to bring it down to the scratchpad before appending the distance but that seems to be what you need to do.

Hopefully that makes sense.

Oh, and I checked, SEA and PAE are 29nm apart according to my low enroute chart and with the above method I can now enter track waypoints less than 1nm from the original (although even I'm not sure why I'd want to!) and if you type a distance which is further than next waypoint, it will rightly come up with 'Invalid Entry'.

[thibodba57 462]

You can type a fix or LSK when making a custom point.  It will not make a difference in the real aircraft.