An enhanced LOng RAnge Navigation (eLORAN) system may include a plurality of eLORAN transmitter stations, and at least one eLORAN receiver device. The eLORAN receiver device may include an eLORAN receive antenna, an eLORAN receiver coupled to the eLORAN receive antenna, and a controller coupled to the eLORAN receiver. The controller may be configured to cooperate with the eLORAN transmitter stations to determine an eLORAN receiver position and receiver clock error corrected from additional secondary factor (ASF) data, the ASF data based upon different geographical positions and different times for each different geographical position.