a test systemwas assembled to explore the concept of aircraft positioning by combining inertial navigation system data with DME range measurements acquired sequentially from multiple stations. Post–flight processing software was developed using computer simulated data, with many of the predicted performance parameters later confirmed by flight tests. The results indicate that horizontal positioning accuracies of ten to fifteen meters (CEP) and rms velocity errors better than 0.1 meter per second are achievable with the syste