Distance/position reporting

[mcganz121]

Hi- I fly in an a2a pa28 that does not have GPS. What is the best rule for determining distance from an airport (or vfr marker) when making initial contact? I know you can use a dme; however, this gets a bit tough when heading through, for example, the mini route which has multiple hand offs in short order.

Thanks!

[BFG]

If I'm navigating VFR without GPS, I'm navigating via my chart and pretty much constantly estimating my position against it. In terms of distance, a VOR rose on the chart is 10 miles across, and you can use that as a quick benchmark for estimating distances.

Also I would suspect this doesn't have to be exact for handoffs. I presume the distance / direction reporting is to make it easier for the controller to pick up your bogey on their screen. If they have any doubt they will ask you to IDENT.

[mcganz121]

Thanks... the VOR rose tip is helpful

[Kyle.Sanders]

Generally speaking:

VOR Ros = 10 miles accross

Inner airspace surface area of Class C airports are 10miles accross.

Shelves of class C and B (again- generally) are 5 miles wide.

You then have VFR reporting points on the VFR sectionals and TAC charts. Sometimes reporting "we are over signal peak" is the best report you can give.

[Justin Lerner]

I also sucked (past tense) at eyeballing distances in the sim and at least one aircraft I use is /U, so I use a combination of the tricks above. VFR reporting points are my favorite because I can be as general as I want, e.g. "Just north of the Rose Bowl" "Overhead Huntington Pier" "Abeam the Queen Mary" etc. You can bet if it's on a VFR chart, ATC is well aware of it and they'll know exactly where you are as soon as you say so.

One trick that has helped me get a sense of distance in the sim is a particularly handy feature in X-Plane where you can choose a starting position like a 3nm final to a runway. So I'll load up the sim (offline of course) at that starting point, pause, and take a good look at the sight picture so I know (roughly) what 3nm looks like for later. Of course, you can do this in any sim. Just set yourself up on an ILS and pause at various DMEs, or manually slew your airplane around in the world, or mess with the weather visibility until you're comfortable with identifying distances. It doesn't have to be exact when you're telling ATC where you are, close enough is good enough (but make sure that's where you really are!).

[Justin Lerner]

Oh yeah! And remember the higher you are, the more fudge factor there is in the DME range because it's not measuring your ground distance. It's measuring the distance between the DME source and your airplane. At lower altitudes like the ones you'll be flying in a PA28 this really isn't much of an issue, but for example if you're overhead a DME at 17,000' you're almost 3nm above that DME and that's what it'll read on the display.

17 ÷ 6 = 2.83 which you can just round up to 3.

(There's actually 6,080' in a nautical mile, but thanks to KISS we can just divide our altitude by 6,000).

[Matthias Geiss]

There are differences between charts regarding the diameter of VOR roses. But of course the chart's legend usually provides a scale so it's easy to check wich diameter is used on the one you are looking at.

Looking at the LA TAC chart, the VOR roses are 10nm in diameter:




While on the normal sectional the diameter is 20nm:




On the Heli chart, it's 5nm:

[Peter Grey]

There are differences between charts regarding the diameter of VOR roses. But of course the chart's legend usually provides a scale so it's easy to check wich diameter is used on the one you are looking at.

Yup, however they are all standard on a given chart.

So here is the handy conversion text to go with the images you posted:

Heli Chart: 2.5 mile radius (1:125,000 scale)
TAC: 5 miles (1:250,000 scale)
SAC: 10 miles (1:500,000 scale)
WAC: 20 miles (1,1,000,000 scale)

There is a pattern

Don't worry about being 100% exact with positions, if you say you are 5 miles out instead of 7 it doesn't really hurt anything from an ATC point of view.

[rtataryn]

I'm not as good at judging distances in the sim as in the real world, but either way I don't like guessing or staring down at maps on my lap when flying. For distance reporting I use the "NEAREST" function on my GPS. A quick press of a single button and you have exact distances to all nearby airports. A click of a dial and you have exact distances to the nearest VORs. No guessing. I know you said you don't have GPS, but for this purpose it really is nice.

[rtataryn]

I had a chance recently to fly a PA-28. It was a 1962 Cherokee 140 with all original avionics, interior and paint - It was a museum piece with only 600 hours on it, so it was quite a joy and privilege. Anyway, I was having to make a couple of distance estimates and calls without the benefit of GPS and realized how dependent on it I'd become. Back in 2003 when I owned a Cessna Cardinal RG I purchased a handheld GPS, a Garmin 190. I loved it and never flew without it once I had it. Later I upgraded it to a Garmin 490. It also had a nearest function, so it was perfect for situational awareness and distance measurements, even when I was flying older aircraft without built in GPS. Which brings me to my thought here . . . If I were flying in the "real world" an old PA-28, Cardinal, Luscombe, Champ or whatever, I would be carrying my 496. Are there Simulation handhelds available to have in the sim cockpit? This would be a great solution and very realistic IMO.