The Longley-Rice and Johnson-Gierhart tropospheric propagation programs are particularly useful in predicting propagation losses for paths over irregular terrain commonly encountered in ground-to-ground, air-to-ground, and air-to-air military tactical scenarios. These programs use an empirical database to statistically weigh knife-edge diffraction losses with losses from multipath interference, smooth-spherical Earth diffraction, and troposcatter modes of propagation. The purpose of this paper is to provide perspective concerning the use of the two programs. Emphasis is placed upon the regions of applicability for the programs and on factors that must be considered in selecting and specifying the input parameters. Numerical results are given for various scenarios and ranges of input parameters.