Autopilot, FMC, and DME Arcs

[HighFlier 17]

Hello,

I was just wondering if a fellow pilot could assist me with the autopilot of the 777 (in other words I'm not asking for PMDG staff to help me). Today, I'm flying from RJTT to RCSS. Usually, my flight planning involves a copy and paste of the flight plan of the real flight I see on flightaware. Sticking with this, the real flight is using the AA1B STAR into RCSS. Looking at the chart, I saw something I've never seen before. It says to join (and subsequently fly) a DME arc. Is it possible to program the FMC of the 777 to fly said arc? Or do I have to fly that manually? If it is possible to have the autopilot fly the arc, how would I program the FMC to have the autopilot do so?

Thank you in advance (and sorry for the inconvenience),

James

[Nighthwk 566]

You'll need to hand fly it, from what I've heard. Other than that, I can't really help you there.

[Chock 17,769]

 

It depends on whether the procedure is in the FMC's database, some are, some are not, but if not, you can program it in manually, with a bit of faffing about. Normally you would simply fly for a bit on a heading the correct distance from the DME arc's navaid, then turn ten degrees to maintain that same distance from the DME nav aid, then fly a bit more, then turn ten degrees again etc, or, you could turn smoothly and maintain the distance constantly if you liked, but to do it automatically if there is no DME arc in the FMC already, here's what you can do to program it in to an FMC (this is not the only way to do it incidentally, but it probably is the easiest way to understand)...

Let's say we want to fly a DME arc around the TNT VOR, and we want that arc to be ten miles out from the location of the VOR. We can add a bunch of manually placed radial waypoints around it in a circle, like the spokes of a wheel, with all of them 10 miles from the VOR, which is what I have done in the screenshot below. You can see some of them on the PFD.

To do that, I placed a waypoint 10 miles out from the TNT VOR directly east of it, by typing TNT090/10 into the scratchpad and then entering that as a waypoint on my flight plan, then I added one at TNT100/10, then one at TNT110/90 etc, etc. You can see in the screenshot that I was up to TNT180/10, which would have then meant I had one quarter of the arc around the TNT VOR programmed into my route. This gives us a magenta flight plan line which is on that arc 10 miles out from the TNT VOR. You could then fly it manually using the magenta line as a guide, or have the autopilot do it. Personally, I would never really be bothered to do this and its practicality is a bit questionable anyway unless you were certain you were gonna be flying it, but this shows you how it can be done completely automatically putting it in manually, if you really want to...

[jbcallender 53]

Can't you create fixes that are a fixed distance from a known point along different radials?  that would create a DME arc.

Jeff Callender

 

[spesimen 135]

the points along the DME arc load automatically if you enter the STAR in the FMS anyway. 

in the FMS select STAR->AA1B  , approach LDA28 (the IAF matches the end of AA1B), transition ->BESOM

cheers,-andy crosby

 

 

[downscc 1,327]

20 hours ago, jbcallender said:

Can't you create fixes that are a fixed distance from a known point along different radials?  that would create a DME arc.

Jeff Callender

 

You can but come on, flying a DME arc should be easier than spending time programming the computer while also on the arrival.  The ND becomes a moving map or sorts and you start flying the RMI..., if you don't have one I recommend them for DME arcs, you just keep the needled pointed off the wing at the station and keep the distance within +/-0.5 nm.  I recommend you slow down.

[CaptainLars 21]

On Tuesday, October 31, 2017 at 1:39 AM, jbcallender said:

Can't you create fixes that are a fixed distance from a known point along different radials?  that would create a DME arc.

Jeff Callender

 

That's exactly what Alan described.