Chapter 7. Navigation

General

Navigation in the North Atlantic, or in any oceanic area for that matter, is considerably more difficult than over land. There are no landmarks, and short range navigational aids (VOR/NDB) are few and far between. Your aircraft should be equipped with some type of Long Range Navigation (LRNS) equipment for your flight. Loran C, a popular type of area navigation in many parts of the world, is NOT reliable in all areas of the North Atlantic because of poor ground wave signal coverage in some areas. This statement contradicts some maps depicting Loran C ground wave coverage, but experience demonstrates that you should NOT use Loran C as your sole means of area navigation in the North Atlantic, except in certain areas. For these reasons and due to the decommissioning of Loran C stations in the region, we cannot publish Loran C coverage charts for the NAT. The United States and Canada have approved GPS for use in the Ocean under certain conditions (see Chapter 3, Navigation Equipment).

The use of a self-contained navigation system INS/IRS is recommended.

On the Northern routes it is important to note the pronounced magnetic variation--up to approximately 40 to 45 degrees - and the "pull" this variation has on your compass. When performing turns or accelerations, this "pull', termed the "dip effect", causes your compass to turn slower than you are used to in the lower latitudes.

Even with a sophisticated navigation system such as GPS, it is still essential to maintain good navigation practices. Do not just blindly follow the numbers; awareness of the azimuth of the sun, cross-checking with other NAVAIDs and disposition of contrails from high level traffic are all obvious but many errors have occurred which could have been prevented had the pilot shown more awareness.

Route Concerns

There are a few VOR/NDB routes in the North Atlantic. These routes are sometimes known as "Blue Spruce" routes and are depicted on navigation charts from Jeppesen and other sources (see Chart # 1). Other than the Blue Spruce routes, there is little NAVAID coverage at the low altitudes in the NAT. The chart in this manual depicting radio coverage is calculated based on theoretical coverage; actual coverage may be considerably less than that shown, and these charts should by no means be used for navigational purposes.

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