To gain better insight into the practical limits of applicability for TLEs, SGP4 and the underlying GP theory, the
native SGP4 accuracy is parametrically examined for the statistically-significant range of RSO orbit inclinations
experienced as a function of all orbit altitudes from LEO through GEO disposal altitude. For each orbit altitude,
reference or “truth” orbits were generated using full force modeling, time-varying space weather, and AGI’s HPOP
numerical integration orbit propagator. Then, TLEs were optimally fit to these truth orbits. The resulting TLEs
were then propagated and positionally differenced with the truth orbits to determine how well the GP theory was
able to fit the truth orbits. Resultant statistics characterizing these empirically-derived accuracies are provided.