The Coast Guard Research and Development Center has developed "Coast Guard POSAID2 ver 2.1a", a DOS-based program for converting LORAN-C TD's to latitude and longitude. The conversion is based on the Sodano (1965) method taken from McCullough, J, et al, "LORAN-C Latitude-Longitude Conversion At Sea Programming Considerations". The original reference for the conversion is: Sodano, E.M., 1965, General non-iterative solution of the inverse and direct geodetic problems: Bulletin Geodesique, annee, Nouvelle Serie, no. 75.