Why not Mercator projection?

Question

Aviators prefer the Lambert projection and seafarers, the Mercator one. It makes sense: aviators navigate often by radio signals that follow the great circle or gnomonic path, closer to Lambert, while seafarers follow a rhumb course as a straight line on the Mercator.

But when I use my GPS moving map in my little aircraft, if e.g. I head west from my location in Norway, and zoom out to show north Europe, my heading point towards south England and not Scotland, as it should if I was flying on a compass course of 270. This is because the great circle from my latitude 60 north, bends southward on an initial heading of 270.

I know, gnomonic navigation is the path of the shortest distance and what we would prefer as pilots. But I have never been flying more than 20 minutes without a waypoint on a flight plan, hence flying from point to point in such short distance that the gnomonic vs. rhumb line doesn't make a difference.

So, why not using Mercator in the air? Pilots did it in the past, when they navigated with a bubble sextant, needing spherical trigonometry.

? · Accepted Answer

The use of a Mercator projection in maps is not a real problem for use for short distance (flight) planning - But it becomes a problem when your legs are in excess of 200/300 NM -

In the days of navigators (then flying the 707 of Jurassic era) l discussed a lot with the navigators as far as map projections - choice of Mercator and Lambert - Of course the best practical maps were Lambert projections, such as on the GNC, and the GNCC world maps used by navigators -

I could ask similar question then - not about using Mercator or Lambert, but instead using Magnetic, true or GRID degrees for routes and headings - I have used "Grid North" for navigating in the Arctic areas on flights such as Fairbanks (Alaska) to Thule or Sondrestrom (Greenland) - and Grid Nav sure made things simple as well -

Since airplane autopilots use Inertial Nav with GPS update... I do not give myself a headache with Mercator (a good Belgian astronomer/scientist) or Lambert...! -

Salut Michel...!
Faut pas pousser Bobonne tout de même avec tes cartes Mercator...
C'est juste bon pour emballer tes sandwiches, ou faire des cornets de frites -
.

Tracy L · Answer

A lot of GPS units allow chart selection so the operator picks the "projection" wanted based on the chart displayed. The fact is that as long as you know where the aircraft is located and where it is headed and the heading needed to get there the map shown really makes very little difference. The airspace is more important than the ground while enroute. Just my opinion.

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Why not Mercator projection?

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