DME Arc

Ventucky Red

Ventucky Red

Pattern Altitude
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Jon
As part of my IPC ride this coming weekend it is being asked that I do a DME arc.. of course there are no DME Arc approaches in my area so this will be a simulated situation...

I was never taught this nor have I ever flown one.. Any advice on how to master this? It look pretty straight forward once I set up the metal picture...

Thanks
 
Basically just fly it as a series of straight lines. When on the arc, turn a few (10?) degrees to the inside. Fly that heading until you are just about to touch the arc (DME range = arc radius) then turn again. And don't get outside the arc.
 
Of course, the procedure is conceptually easy and I assume you understand the step by step process. Usually the trick is how to adjust for wind as you fly the 10 degree segments around the arc. As long as you keep a mental picture of what's going on and how the wind will effect the segment headings AND keep track of the DME.

If the DME shows you getting closer then use less correction. If it shows you getting farther then use more correction.

Use 2 an 3 degree corrections off the reference heading. Small changes are the key.

tex
 
:yeahthat: Additional points.
 
Turn ten, twist ten, cha cha cha
Turn ten, twist ten, cha cha cha

Seriously, this is how I was coached by my instructor.... But this video does a good explanation

 
and @Ventucky Red, your aircraft does have something that permits DME?

If it's a function or page of your GPS, have that set up the way you want it before the flight.
 
First question... do you have a DME? They are outside the scope of tasks for an IPC. Inquire why your instructor thinks they are required or even a good idea.

But anyhow, an arc doesn't require an approach. All you need to be told is a heading or radial to intercept the arc, and which way and distance to fly it. If your DME (or whatever you are substituting) reads in tenths, sticking within the assigned space is pretty easy. At the arc distance take a heading roughly 90 degrees to the radial and hold that. If the numbers are getting smaller turn outwards a few degrees. If the numbers are getting larger, turn inwards. Lather, rinse, repeat. Frankly it's no different than bracketing any other course other than the fact that you will necessarily have to make corrections as you go along.
 
jsstevens said:
Basically just fly it as a series of straight lines. When on the arc, turn a few (10?) degrees to the inside. Fly that heading until you are just about to touch the arc (DME range = arc radius) then turn again. And don't get outside the arc.
Click to expand...

Protected airspace is just as wide as a plain-vanilla Victor airway. BTW, look at the arcs into SLC...you don't want to stray outside protected airspace inside OR outside.

Bob
 
You need to start your turn before you get to the arc. If you are following a radial from/to the VOR that defines the arc your turn will ALWAYS be 90 degrees.

Find out how far it takes you to turn 90 degrees at the speed you will fly the arc. For typical trainer its usually a little more than 1 mile.

Look at the DG 90 degrees from/to your current heading, remember it, and turn to that heading (if its windy, watch out!). Have the freqs all highlighted on the approach plate so you dont have to take your GPS off the distance to the VOR to find them, you might get off the arc if you do (if you are using a GPS for the distance to the VOR). Arcs are sometimes quite long. Dont overun the inbound course to the approach!

If the guy is going to make one up, ask him to draw it up so you know what to do. Home made approaches tend to get kinda funky because there is no approch plate :-(
DME.gif
 
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AggieMike88 said:
Turn ten, twist ten, cha cha cha
Turn ten, twist ten, cha cha cha
Click to expand...

Thanks for that video Mike... appreciate it.. and the "turn ten, twist ten cha cha cha" works for me.

flyingron said:
First question... do you have a DME? They are outside the scope of tasks for an IPC. Inquire why your instructor thinks they are required or even a good idea.
Click to expand...

Yes there is a DME in the plane that I rent and fly.... I was asked to about this approach....

http://155.178.201.160/d-tpp/1704/05222VDTZ15.PDF

Oh! forgot DME Arcs are in the IPC standards.. or am I misinterpreting this?

V. NAVIGATION SYSTEMS
A.Intercepting/Tracking Navigational Sys-
tems and DME Arcs
 
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That one looks like fun.... Arc to the runway, arc to your missed approach hold fix.
 
Ventucky Red said:
As part of my IPC ride this coming weekend it is being asked that I do a DME arc.. of course there are no DME Arc approaches in my area so this will be a simulated situation...

I was never taught this nor have I ever flown one.. Any advice on how to master this? It look pretty straight forward once I set up the metal picture...

Thanks
Click to expand...
It's just as straightforward and easy as what you visualize.
 
Ventucky Red said:
Thanks for that video Mike... appreciate it.. and the "turn ten, twist ten cha cha cha" works for me.
Click to expand...
One additional tip, set your heading bug for the point when you need to stop the arc. This will remind you to not continuing "cha cha cha-ing" beyond where you really want to be.
 
And for an uncharted DME arc, there is a way to set it up in FF.

Consider the VOR/DME RWY 17 for Decatur, TX (KLUD) http://155.178.201.160/d-tpp/1704/06190VD17.PDF

If I wanted to start at 25 DME on the 090 Radial of the BOWIE VOR, then turn Left at 15 DME and arc to ENTUR, I would enter the following into FF to get it to plot the waypoints to follow:

UKW/90R/25 UKW/90R/15 UKW/100R/15 UKW110R/15 UKW/120R/15 UKW/130R/15 ENTUR​

Each "VOR/RADIAL/DISTANCE" block allows FF to define that user waypoint. When chained together like I showed, it helps define a DMR arc.
 
AggieMike88 said:
And for an uncharted DME arc, there is a way to set it up in FF.

UKW/90R/25 UKW/90R/15 UKW/100R/15 UKW110R/15 UKW/120R/15 UKW/130R/15 ENTUR

Each "VOR/RADIAL/DISTANCE" block allows FF to define that user waypoint. When chained together like I showed, it helps define a DMR arc.
Click to expand...

Learned this little trick the other day... we have an aerobatic practice area (box) that i wanted to highlight and I loaded some similar route instructions into FF... pretty cool... and I like heading bug idea.. that will keep me turning in the right (or left) direction.
 
I find DME arcs to be dirt simple. Once established I set the DME to show speed to station. Hold that at 0 and you're set. Remember, the tolerance on distance is +/- 1 nm, and that's a lot of space. When flying a DME/VOR approach (like the one to rwy 35 at OLM) I just stay on the arc with the OBS set to the inbound course. When the needle gets close (like about 30 seconds from centering), start the turn. Of course, the countdown timer in the 430W makes figuring out when to start the turn even easier. But I still like using the actual DME to fly the arc.
 
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