## Coordinate CalculatorTM Java Applet

This Java applet is a very powerful tool for calculating location, bearing, distance, time enroute, winds aloft, headings and more. The Coordinate Calculator(tm) is very easy to use. Simply enter the information you know in the appropriate input fields, and press [Enter] to perform the calculation, and the answers appear in red.

The Coordinate Calculator has many built in formulas it goes through to determine unknown values. Also, the given values are cross checked to make sure all the information is consistent: for example, distance must equal the time enroute times the ground speed. If values do not make sense, a 'consistency error' is shown.

Much effort was expended to assure the accuracy of the calculations. The great circle math routines (used for distance and bearing) are implemented from Sodano's method, as also used by the FAA for determining routes. However, when the distance being measured is less than 1.25 nautical miles, a standard X,Y grid is used after properly scaling both the X and Y axis to the ellipsoid. The X,Y technique is used because the great circle routines lose their accuracy for these very short distances. The WGS 84 ellipsoid is also used for calculations. The winds triangle calculations use simple trigonometry and do not account for curviture of the earth. This should not be a problem with distances shorter than 200 miles.

Input Fields

 Latitude: Holds the latitude of the Start or Dest. (destination) coordinate. Unless specified, the latitude is assumed to be North. The value can be entered in many different formats. All the following are valid and represent the same longitude: N38 22.50 or N3822.50 or N38 22 30 or 382230 Longitude: Holds the longitude of the Start or Dest. coordinat. Unless specified, the longitude is assumed to be West. The following examples represent the same longitude: W122 38.25 or W12238.25 or or W122 38 15 or 1223815 Mag.Var.: This is the magnetic variation. Unfortunately, this applet does not calculate the variation for you. It will automatically assume 0 if you don't specify it. Distance: Distance between the Start and Dest. coordinates displayed in the selected units. This value can also be calculated based on the ETE time and Ground speed. True Course: True course between the Start and Dest. coordinates. Mag.Course: Magnetic course. Adds the true course to the magnetic variation. Airspeed: Airspeed, in the selected units. Calculations for this value are based on the wind triangle. If no wind triagle is specified, then Airspeed may be set to the ground speed. ETE time: Estimated Time Enroute. Calculations to obtain this value are based on Distance/GroundSpeed. Values are to be entered with hours:minutes and optional :seconds; e.g.; 1:45 or 1:45:00. Wind from: Angle the wind is coming from, in magnetic degrees. All calculations are based on the wind triangle. Warning: this value must be entered as magnetic degrees. Weather stations usually report winds near the surface (below 3000 feet AGL) in magnetic degrees, but winds aloft (at 3000 feet AGL & up) are usually reported in true degrees and must be manually converted. Windspeed: Wind speed in the selected units. All calculations are based on the wind triangle. Cor.Angle Wind Correction Angle in degrees. Calculations for this value are based on the winds triangle or the difference between Mag.Course and Mag.Heading. Mag.Heading: Magnetic Heading (in degrees). This is the Magnetic Course with a correction for winds. Mag.Heading = Mag.Course + W.Correction. Groundspeed: Ground speed in the selected units. Calculations for this value is based on the wind triangle.

Buttons

 Calculate Select this button to perform a calculation based on the 'given' (black) values. All currently calculated (red) values are cleared for the new set of calculated values. If any 'given' values are not formed correctly, an appropriate error message is shown and input focus is given to the erred value. You can also call 'Calculate' by pressing [Enter] when input focus is on any input field. Coord Fmt. Coordinate Format. Select this button to change the displayed format of the latitude or longitude coordinate fields. This button does not affect the format of how the coordinate is read in. One handy way to use the coordinate format feature is for converting between different formats. For example; you can enter a coordinate value in say Degree minutes and seconds form (e.g., N38 25 30) and press Enter to convert it to Degrees and decimal degree format (e.g., +38.42500 ). Units Changes the Distance and Speed units. Cylces between Nautical, Statute and Metric units. This button also causes a calculation to be performed.

Coordinate Calculator(tm)