Who's wrong? ERSA or Google Maps?

[Bosi72]

The simpler way would be using EFB instead of Google.

 

The example screenshot is below showing Bearing from Gilgandra to Tooraweenah  30deg Magnetic with distance of 20.9nm.

 

To calculate aircraft Headings, you would need to know the wind direction/speed.

 

 

 

[Garfly]

49 minutes ago, old man emu said:

NEXT QUESTION:

If  I have a Google Map and measure the bearing of Point B from Point A, is it Degrees True, or Degrees Magnetic?

 

If that bearing is from the 10 NM boundary, should I report the Heading from that point to Overhead Runway as X degrees (T), or X degrees (M).?

I'm not sure how Google Maps handles that but the app is not really designed for that sort of thing, is it?  Even if you never want to take one of those new fangled EFB gizmos aloft, I'd strongly recommend using one of them for the job at hand.   It'd make it so much simpler and better in so many ways.  By sticking to  "the narrow path of virtue" (to borrow Nev's phrase) even for the planning phase, I reckon it's going to be harder and less accurate. Unless you reckon virtue is its own reward.   ; - )

Edited January 1, 2023 by Garfly

[facthunter]

CDMVT.  Can dead men vote twice..  Compass Deviation Magnetic Variation True.  Variation Varies depending where you are and since you can't PROJECT something from a sphere to a flat surface accurately and without distortion you must choose what projection you will use and now how to derive tracks and distances from it. The Usual one is Lamberts Conformal orthomorphic based on 2 selected Parallels of latitude and unless you fly true north south or on the equator you need to calculate the  ever changing track to fly a great circle to do the shortest distance.  Nev

[Garfly]

13 minutes ago, facthunter said:

CDMVT.  Can dead men vote twice..  Compass Deviation Magnetic Variation True.  Variation Varies depending where you are and since you can't PROJECT something from a sphere to a flat surface accurately and without distortion you must choose what projection you will use and now how to derive tracks and distances from it. The Usual one is Lamberts Conformal orthomorphic based on 2 selected Parallels of latitude and unless you fly true north south or on the equator you need to calculate the  ever changing track to fly a great circle to do the shortest distance.  Nev

But since we're talking Toora we can bank on variation (in our lifetime, at least) to remain at 11 - legs eleven - degrees, East.   ;- )

 

 

 

Edited January 1, 2023 by Garfly

[Bosi72]

Biddon Township - Tooraweenah

024M 9nm

 

 

 

 

[turboplanner]

3 minutes ago, Bosi72 said:

Biddon Township - Tooraweenah

024M 9nm

 

 

 

 

I see this map has a handy magenta line to help people sort it out.

[facthunter]

Yes t doesn't change much but you notice it sometimes with Runway designations that are to the nearest 5 degrees of the  designator. 226 becomes 23 not 22 In Canada the north magnetic pole is nowhere near the  true north pole.  Nev

[Bosi72]

Hickeys Falls 075M 9nm

 

[facthunter]

What about the Compass deviation card.? For  320 fly 322 (example)  AFTER you account for wind drift. How long since you  swung your compass and is it for the southern hemisphere?

[Bosi72]

Tonderburrine Rd   296M 11nm

[Garfly]

35 minutes ago, turboplanner said:

I see this map has a handy magenta line to help people sort it out.

Actually the new WAC itself doesn't offer much guidance on the Romeo areas contained in those magenta boxes.

However, a single long press on your EFB screen will reveal that R559D and R559E are active only between FL100 and FL260.

So no sweat.

 

CLICK FOR FULL REZ:

 

 

Edited January 1, 2023 by Garfly

[Garfly]

6 minutes ago, facthunter said:

What about the Compass deviation card.? For  320 fly 322 (example)  AFTER you account for wind drift. How long since you  swung your compass and is it for the southern hemisphere?

That old path is sounding less and less virtuous by the minute.  

[facthunter]

WE are only  considering very small distances. Do you notice how your WAC charts do not match at the top and bottom borders?  Nev

[Bosi72]

14 minutes ago, facthunter said:

WE are only  considering very small distances. Do you notice how your WAC charts do not match at the top and bottom borders?  Nev

I was taught when flying Navs using "Watch-Map-Ground" technique to orientate charts in the direction of the flight.

So, for example in screenshot below, if I'm coming from the North, I would rotate paper charts upside down, like in the screenshot below.

Good thing in EFB, there is a button which enables "Free rotation" mode (red arrow pointed). 

In any case, the bearings, distances will remain unchanged.

 

[Yenn]

The non matching is because  a minute of longitude is only a nautical mile at the equator, it gets less as you go South in Aus.

[facthunter]

Some people do have difficulty with it the other way, but a few prefer it. Whichever way you orientate best.  I agree Yenn  and for the same reason where you derive/ measure your chosen track from will affect the accuracy of it . Lamberts is CONICAL orthomorphic and the best for area and proportion.  Mercator is so distorted near the Poles it's useless. WAC charts are Lamberts and most  things are close to being right. If you cross a lot of longitude you might measure the !/2 way mark tor track required.   Nev

Edited January 1, 2023 by facthunter

[old man emu]

Will you people stop demanding that I go out and buy some software?

 

I'm sitting in the heat trying to produce something to assist safe arrival at Toora before the contest starts. I'm not trying to provide IFR tracks, simply trying to produce a mud map with local knowledge. Once again, I ask a simple question and get the ins and outs of a duck's arse. 

 

This is useless:

 

For a start the measurement is not even on the 10 Nm circle.  I've actually been out there by car to see for myself what landmarks there are. I guess the best thing I can do is to ignore bearings from the locations to Toora and let electronic gizmos be the guide.

 

Thanks Garfly for posting that bit of the WAC chart and further info. Now I don't have to worry about those Rs & Ds.

 

 

[turboplanner]

37 minutes ago, facthunter said:

WAC charts are Lamberts and most  things are close to being right. If you cross a lot of longitude you might measure the !/2 way mark tor track required.   Nev

For people like me that fly within 0.5 deg of track Lambert's is important, however, for the competition what about using WAC Track figures and let the PIC convert to magnetic, compas deviation. That shoud spread the field out nicely.

 

[Bosi72]

8 minutes ago, old man emu said:

Once again, I ask a simple question and get the ins and outs of a duck's arse

woww.. 

 

A friendly suggestion, contact your flying instructor and revisit navigation topics.

 

Good luck with organising the competition..

 

[old man emu]

6 minutes ago, Bosi72 said:

A friendly suggestion, contact your flying instructor and revisit navigation topics.

I get quicker, more reliable answers here from people I have learned to trust over many, many years. And until CASA pulls out its finger and returns my Part 61 licence, I can't even go do a medical, let alone go fly. So I haven't engaged an instructor.

 

Some think that all that's involved in organising a flying event that has CASA approval is to ring them up and tell them what YOU are going to do. Unfortunately, that's not the case. Do you know what the acceptable separation distance is between aircraft taking off? Have you ever done a Risk Survey/Risk Assessment and then developed procedures to deal with risk?

 

 

[old man emu]

16 minutes ago, turboplanner said:

for the competition what about using WAC Track figures and let the PIC convert to magnetic, compas deviation.

I'm having nothing to do with how a PIC prepares a plan for the contest. At the moment I'm just trying to get a heap of planes of varying performance, coming from multiple directions at the same time onto the ground at an aerodrome that the majority will never have been to, or even heard of. Just take a look at the WAC, or whatever you use and figure out how to avoid the big lumps in the surrounding countryside.

[Thruster88]

I personally think you should just use the standard CTAF procedure. Having aircraft converge at some other point away from the runway will not make it safer. There is no liability on you if standard CTAF procedures are used.

[facthunter]

With google earth etc and normal  adequate  planning it's no worse and a lot better than other such destinations people fly to. It's not your  responsibility to do much more than supply a windsock and the more you do the more liability you assume. They brought ATC into Airshows doownunder and I got stuck there an extra DAY because of their trying to big deal charter light twins in and out. As it got to the afternoon of the 2nd day I started my engine and told the tower where to  look for me and that I wanted out of there and that I would be ready for immediate departure approaching the threshold. At 500' I requested a right turn to exit their temp control area and cleared their frequency not long after tracking for Lethbridge. Could have just as easily been done the day before. Out of their way in minutes..

  We can't perform any control function. You could have a trike or Quad bike with a follow ME sign. I suppose.

  Airccraft following others at take off should wait till the preceding aircraft is airborne and clear of the runway. but YOU (or your helpers) can't give clearances..Nev

[old man emu]

50 minutes ago, Thruster88 said:

Having aircraft converge at some other point away from the runway will not make it safer.

Better to ask politely for people to  approach in an orderly manner than have them come from every which-way. At least if people approach along the same path, it makes it easier to "See & Be Seen" Or am I a fool who thinks that normal people are happy to cooperate?

 

54 minutes ago, Thruster88 said:

I personally think you should just use the standard CTAF procedure

That's the idea. It will remain an uncontrolled aerodrome at all times. 

 

32 minutes ago, facthunter said:

We can't perform any control function.

No, and we don't want to. The only controlling we want to do is when we are marshaling contestants and getting them ready to take off. Simply as part of the operation of the contest, contestants will line up, and the Starter will say Go!, after the Starter has been advised that the separation to the preceding aircraft is sufficient for the following aircraft to begin a take-off run.

 

And for the doom-sayers, there will be a special word broadcast if there is an incident that puts the runway out of service. When that word is broadcast, all engines stop, and aircraft in the air will have to head off to the nearby alternates and land there to wait until the runway is serviceable again. 

[Blueadventures]

22 hours ago, RFguy said:

Where things become tricky and errorsom  is conversion of spheroids...

 

This usually occurs between sperical (lat long) and easting/northing etc cordinates, as , as nev says, the Earth is an oblate spheroid.

and also converting from good ol' AMG66 to WGS84 or even MGA84, or even LOCAL datums.

 

Large geo projects like the Snowy scheme have their own local datum, to better approximate the bulging earth in the region.

I got to learn all this when writing radio propagation prediction programs in the 90s, having to work with all matter of map data , fortunately I had a good mate Joe Monardo who was a surveyor.  We had spot height data in AMG66 or a local datum (councils had their own datums)  , and I fed this into a terrain forming program called ANUS-DEM from the ANU which was originally used for catchment predictions.

 

 

We move North about 70mm each year; no wonder its getting hotter were moving towards the equator 🙂