The Great Circle Mapper, including all software, data, and the compilation and presentation of the data is Copyright © 1996-2019 Karl L. Swartz. All rights reserved.
The Great Circle Mapper name and logo are trademarks of the Great Circle Mapper.
Additional credits, copyrights, and licenses apply as detailed below.
Great Circle Mapper software incorporates several third-party software libraries:
Geodesic calculations use custom software based on formulae developed by Thaddeus Vincenty, with modifications by Charles Karney based on work by Friedrich Bessel to improve performance and accuracy. (See How does the Great Circle Mapper calculate distances and paths? in the FAQ for additional information and references.)
Mac and the Mac logo are trademarks of Apple Computer, Inc., registered in the U.S. and other countries. The Made on a Mac Badge is a trademark of Apple Computer, Inc., used with permission.
The Great Circle Mapper uses pre-rendered maps, stored in a custom, high-performance image format. These maps are built offline from multiple sources:
The Great Circle Mapper's location database includes information about landing facilities (including airports) and other types of locations compiled from many sources including those listed below. Specific source credits are noted on the information page for the airport or location.
Magnetic variation information is derived from the World Magnetic Model (WMM), a product of the U.S. National Geospatial-Intelligence Agency (NGA) and the U.K. Defence Geographic Centre (DGC) which was developed jointly by the U.S. National Geophysical Data Center (NGDC) and the British Geological Survey (BGS). This data is in the public-domain and is not subject to copyright protection.
Time zone definitions including daylight saving time (DST) transitions use the public-domain Timz Zone Database (aka tz or zoneinfo). The time zone for a given location is derived from official airport data or other sources and may not be correct.
Weather data (METAR and TAF) is from the NOAA Internet Weather Source.
Flags used on the airport information pages are from one or more of the following vexillological sources:
Information on this site may not be accurate or current and is not valid for flight planning or navigation. No warranty of fitness for any purpose is made or implied. Flight planning and navigation should only be done using official charts.
Copyright © 1996-2019
Karl L. Swartz.
All rights reserved.