A free, browser-based aviation mapping tool built for pilots, dispatchers, students, and anyone who wants to understand how aircraft get from A to B — and exactly how far they can go under real-world wind conditions.
Accurate wind modelling is the technical heart of Great Circle Pro. All range circles and flight time calculations use real 250 hPa jet-stream winds — the pressure level corresponding to roughly 34,000 ft where most long-haul jets cruise. Three percentile models are available, each serving a different planning purpose:
NOAA's Global Forecast System provides a fresh 250 hPa wind profile every 6 hours. Great Circle Pro samples 18 latitude bands from equator to pole, computes the mean zonal component for each, and applies it across 720 radial bearings. This is the default and most accurate mode — the range circle you see reflects today's actual jet stream position.
The wind speed exceeded only 15% of the time at each latitude. This is the model commonly referenced by aircraft manufacturers for ETOPS diversion planning and widely adopted in airline dispatch. An aircraft that can reach a diversion airport under 85th-percentile winds can do so on the great majority of real-world flights. Great Circle Pro uses this as its benchmark for ETOPS sensitivity analysis.
The wind speed exceeded only 5% of the time — essentially the worst conditions a route will realistically encounter. Useful for conservative range planning, understanding absolute minimum fuel reserves, or stress-testing whether a thin ETOPS margin holds up under adversarial conditions.
The median wind speed at each latitude — what you'd expect on an average day. Useful as a baseline for comparison against the 85th and 95th models, and for understanding typical block times rather than conservative planning figures.
Jeff S. is the creator and aviation enthusiast whose career spans hands-on flight operations, airline network planning strategy, and technology. He is an ex. corporate pilot on business aircraft, including variants of the Cessna Citation Jet and Beechcraft King Air. He later transitioned into corporate airline roles in International Network Planning & Strategy as well as Revenue Management. With multiple degrees and certifications in Business Administration & Business Technology, Jeff has also built numerous enterprise-level websites for large organizations. Today, he works as a management consultant for a global firm that began in the early 1800s. This tool was built as a hobby in his spare time to combine his operational flying background, airline network expertise, and technical skillset into a precise, practical mapping tool designed for aviation professionals and enthusiasts who demand greater insight into route planning and global connectivity.
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Great Circle Pro is for educational, planning, and analytical use only. Wind and fuel figures are estimates. Not certified for operational flight planning or dispatch use.
See the full feature list, learn how the great circle calculations work, explore the aircraft database, or read our guide to aircraft range circles. For common questions about great circle mapping, check the FAQ & glossary.