Hello

Great job you did, it works nearly perfect for my. The failure the formula calculate is about 1000 m each 1000 km, so pretty accurate.

I am in the process to build three circle around certain airfields. I.E. St. Johns Airport. 1 circle represent 60 min. with a given speed, 1 circle represent 120 ,in. with a given speed and 1 circle represent 180 min. with a given speed. So at the end it will have hundreds of circle around the earth.

Some missing improvements:
Possibility to colorize the full circle (not only the boundary)
Possibility to import places in to the calculator to get Lat and Long in one step.
Possibility to store content. i.E.. Different distances
Possibility to calculate circles for more than one place and more than one distance.

Again it works pretty good and I am happy to found a solution

many Thanks

Thomas