iFly GPS Forum

Ok, *maybe* I have some answers on the airspace rings. Until "yet another" translation from the FAA arrives.

The 5, 10, 30 and etc. mile rings are in NAUTICAL miles.

Except (and isn't there always an except?) around Class D's. They are in STATUTE miles.

Clear as mud? It is for me, too.

On sectionals, how does the FAA draw each? Are they all the Same? Are D's different?

How does iFly draw them? They always seem to overlap the FAA sectional in the places I've been.

But truthfully, I've never used a caliper and measured the size of sectional airspace rings. Maybe I should. There is a D in Tuscaloosa, and the B around Memphis, and the C right here in Huntspatch.

Does the iFly portray the rings in nautical or statute if you have your speed/distance settings in mph versus knots?

Isn't a nautical mile longer than a statute mile? There are more yards in their defiinitions in the nautical.

The iFly airspaces are defined by a collection of lat/lon waypoints which describe the shape. This data is provided directly from the FAA, and it's what we use for Vector mode, and for our alerting. I consider those definitions more accurate than the Sectionals & Tacs; those charts were originally designed for visual, non precise navigation - so the chart designers would commonly move things around to make room for labels and icons. But they seem to be getting better with each cycle.