This paper examines the feasibility of cooperative navigation using relative range measurements and information sharing as a means to limit inertial navigation system error growth in the absence of absolute measurements. This work proposes a suitable decentralized estimator architecture for a community of cooperating vehicles. The performance of the estimator is evaluated using a simulated case study of aircraft using ADS-B/TCAS to cooperatively aid their on board INS during a 60 min GPS outage in the national airpsace. The proposed estimator combines the Supplemented Partitioning Approach with Covariance Intersection. It is shown that this estimator yields conservative results. It is also shown to be flexible in that it places no restrictions on the size of the community or the source selection protocol used by the community. An availability study of cooperative navigation as proposed in the paper around representative US airports was performed. Availabilities between 70-100% were common at major airports like LGA and MSP in a 30 nm,i radius around the airport during morning to evening hours.