ND issue: Direct to a waypoint

[Sylle]

...
Someone has posted a video (737?) some months ago, showing a direct-to arc. But I can't find it anymore.


Cheers,

|-|ardy

You've got mail

Sylvain

[Hardy Heinlin]

Thanks! :-)

Will have to modify my code a bit ...


|-|ardy

[IefCooreman]

If you would go this super-precise way, you'd had to be so consequent and take the wind into account as well, which often influences the radius even more (on depicted non-constant radius arcs).

You're probably right.

Not sure about the wind part. FMC only calculates tracks which are ground based. The autopilot has to adapt the wind influence by adapting the bank, which is not always possible. Undershoots never happen because reducing bank is easy. Overshoots happen frequently and we have the habit for every +45° turn to "re-direct-to" once we we are almost on-track to the waypoint (except for holdings and arc procedures of course). So it's a fairly rudimentary calculation.

[John H Watson]

If you programme a departure at the gate, then do a Direct To (removing the SID or portions of the SID), should the start of the magenta line move from the start of the runway to the aircraft? I recall something similar to this being talked about a while ago, but can't remember if this only applied to a basic company route (with no SID) or to departures, too.

I found this photo in the archives (it's perhaps what I was thinking of)...



If you enter the first waypoint a second time to a route, the magenta line is redrawn from the aircraft's nose.

E.g. First waypoint YSSY, then, I recall, first waypoint deleted, then re-added. I would classify this as a direct to (but because the aircraft speed is zero or because it's on the ground, or because the aircraft is too close to the first waypoint, no arc will be drawn)

In PSX, no matter what I do, I can't get the magenta line to be drawn from the nose of the aircraft on the ground.

Rgds
JHW

[Hardy Heinlin]

This trick now works in PSX as well :-)



Available in 10.0.6-beta5 (not uploaded yet).


Cheers,

|-|ardy


(SY is currently a DME-only station, hence the different FIX INFO symbol.)

[John H Watson]

 

Excellent

I didn't realise that SY had changed... or did you inhibit it via the CDU?

[Hardy Heinlin]

Not inhibited. In cycle 1503, SY is coded as a DME-only station.

[John H Watson]

Strange, even in Beta 5, I still can't get the line to draw like it has in the photo or in your screenshot.

What steps did you take to get the arc to appear? I used the Sydney situ, aligned the IRU's, entered a route (without a SID), deleted the first waypoint, then reentered it. The magenta line still begins at YSSY, not the aircraft.

(EDIT: Maybe I'm too close to the first waypoint and pointing in the wrong direction).

Even so, even if I put the second waypoint in the first line, I would expect the magenta line to go from the aircraft nose.

[Hardy Heinlin]

Delete the origin runway if there is one.

Re-enter the first waypoint while it's still the first one. Don't delete it. Any new entry into a deleted field will not work.