US Sectional Charts

On Saturday, 23 March 2019 04:35:06 UTC+13, wrote:
Is there a (free online) source for sectional charts, downloadable as an image file, that cover your choice of area boundaries, and are "seamless" across a boundary between the official FAA chart sections? My purpose is to view such an image in standard image-viewing software, on a PC (for planning) and on a smartphone (for reference during a flight).

Yes there is. The FAA are here to help you.

https://www.faa.gov/air_traffic/flig..._products/vfr/

These charts are GEOTIFF format and can be used with almost any GIS software.

E.g., our soaring area is near the border between the "New York" and "Montreal" sectionals. In the past I've downloaded both of those sectionals from the FAA web site, cropped to a smallish portion of each, and "glued" together manually in image editing software, trying to line up the longitude lines. That's tedious to do precisely. Also some map features (e.g., some roads or rivers) then still have a discontinuity where they cross the boundary, even as other nearby features cross smoothly. (I have no explanation for that.)

I use QGIS (a free package) to do this. You can load multiple charts and as they are georeferenced they fit seamlessly together.

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Philip Plane