A PHP range calculator for aircraft

We require a tool that provides visitors to our website with a range guide for two corporate jets. Its intent is to show users what journeys can be accomplished with and without a fuel stop and with how many passengers.

It would use London Biggin Hill Airport as the default departure point but use a database of other optional UK airports. The tool will draw a circle on a Google Map marking the range of the selected aircraft with the chosen number of passengers and fuel stops. Adding fuel stops would update the range to encompass a larger area. Removing passengers would increase the distance between fuel stops etc. These variables will be provided as written statements for you to interpret into code.

The tool will fit into an existing page of our site as shown in the image.