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Canadian IFR Charts

Some of the charts show the GPS approach uses True Course. They do not show the equivalent Mag course. The US method shows both Mag and Grid. In the US the Garmin uses Mag and is seamless, but what happens when flying the approach in high latitudes in Canada? Do I see any difference? Will the Garmin switch to true course? How will I know?

How do I find the areas of Canadian MNPS?

What approach are you looking at? All approaches in Canadian Southern Domestic Airspace, including GPS approaches, show directions relative to Magnetic North regardless of lattitude. In Northern Domestic Airspace, which has no major airports, all directions are in True regardless of type of approach GPS or otherwise. No references to magnetic North and you would need to set your DG to true heading and your Garmin to true. I don't know of any navigation system that automatically switches from Mag to True without pilot input. The Garmin has three user selectable modes: True, Magnetic Auto, and Magnetic User.

High lattitudes is not a problem for magnetic compass systems, being close to the magnetic North pole is. This is why high lattitude plates outside of the area of compass unreliability (in otherwords not close to the Magnetic North Pole) still use Magnetic North. High lattitudes are a problem with both magnetic and true headings rapidly changing as you follow a straight line, which is why they use grid reference.

Isn't there a limitation on how far north (or south) you can use some GPS units?

boofhead:

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Those procedures are stored in the nav database in true course.

Is the magnetic unreliability charted? Where could I find that?

At Deadhorse we used grid north..

found more recent mapping
http://i59.tinypic.com/2igkrra.jpg

From our experience in Antarctica, AHRS have limitations on Latitudes but GPS or GNSS units don't.

Which Garmin units are people referring to? GNS 430/530 or G1000?

SB

Where to find the reference? The Canadian AIM publication, IFR charts and FAA Advisory Circular 120-42B, and FAA Advisory Circular 91.70A.

The FAA designates Canada's NCA and Arctic Control Area (ACA) as AMUs. Although Canadian publications sometimes refer to it as the area of compass unreliability, they are the same. The magnetic North Pole is at approximately 75°N 100°W and is slowly moving as it circles the true pole every 960 years. This is why we see current navigation charts occasionally changing an instrument landing system (ILS) course by 1°.

When operating in the AMU, move the HDG REF switch to TRUE when the Canada HI 4 chart defines the course with a °T. Add two additional items to the master flight plan checklist: TRUE HDG adjacent to the first true heading leg and MAG HDG at the end of the AMU. This will serve as a reminder to return to a normal heading reference. The primary reason for selecting TRUE HDG in the NCA and ACA is to provide a more realistic navigation display (ND) heading presentation, thus avoiding rapidly changing heading indications. This will help with radar vectors in TRUE and comply with Canadian Air Regulations.

http://i1047.photobucket.com/albums/...figure_2.3.png

Note the comments in parenthesis on the chart below:
http://i1047.photobucket.com/albums/...eppesen_ap.png

The worst magnetic compass performance is probably in the center of the Northern Control Area, home to the magnetic North Pole. This position creates a notch in the circle of magnetic unreliability, often called a "key hole." Charts should be checked for the presence of a "T" denoting the use of True Heading instead of Magnetic. Some aircraft automatically switch to True based on airway designation or latitude. The G450, for example, automatically switches above N73° or S60° latitude. More about this: G450 Procedures & Techniques / FMS: True/Magnetic Selection.

Ultimately, if you are planning on flying in Canada's Arctic Airspace, contact NavCanda.ca

Additional map and PDF link you may find helpful:
http://i1047.photobucket.com/albums/...M%20Canada.gif

http://www.icao.int/SAM/Documents/20...xp%20Plans.pdf

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Originally Posted by ahramin (Post 9090279)

I don't know of any navigation system that automatically switches from Mag to True without pilot input.

The 747-400 and 777 both switch over to true automatically at the appropriate North or south latitude.

From the 744 FCOM:

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High Latitude Operations
The heading reference for PFDs, NDs, and RMI (if installed) changes to true north at 82°N (or north of 70°N between 80°W and 130°W) or at 82°S (or south of 60°S between 120°E and 160°E).
At latitudes between 82°N (or south of 70°N between 80°W and 130°W) and 82°S (or north of 60°S between 120°E and 160°E), the FMC and IRU reference is determined by Heading Reference switch position. Outside this region, the FMC and IRUs reference true north regardless of Heading Reference switch position.
Automatic switching to a true north reference annunciates by a white box around the word TRU on the ND. A TRUE heading reference can be selected with the Heading Reference switch inside or outside high latitudes. The ND displays a green box around the word MAG to annunciate the change back to magnetic reference. If the heading reference is TRU in the descent phase, the ND displays a flashing amber box around the word TRU.

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Originally Posted by underfire (Post 9090378)

At Deadhorse we used grid north..

WHy? Flown in and out of Deadhorse a bunch, including crewing an airplane based there, and never felt much of a need to use grid azimuths. WHiskey compasses and slaved DG's all seemed to work just fine and match the published mag courses.

That was a lot of help, thanks all.

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Is the magnetic unreliability charted? Where could I find that?

The Jeppesen Atlantic Polar High Altitude en route Chart AT(HI)5 defines the
airspace.

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Isn't there a limitation on how far north (or south) you can use some GPS units?

From our FOM: GPS updating may be available up to a latitude of 88º N. SATCOM may be available up to a latitude of 84º N.

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Originally Posted by 27/09 (Post 9090286)

Isn't there a limitation on how far north (or south) you can use some GPS units?

Could be, I seem to remember reading that when at the far north latitudes, you might be able to catch a signal from orbiting satellites on the other side of the pole. I don't remember seeing any restrictions based on latitude in general GPS info.

I have used a GPS, aftermarket installation at the exact north pole and there was no difficulty. I have not heard anybody mention difficulties at the south pole which is a much busier location with a frequently used airstrip during the summer.