A method, comprising: receiving, from one or more space-based receivers on one or more satellites, both a first message and a second message, the first and second messages (M1; M2) having been received by the one or more space-based receivers from, and both comprising encoded position information for, a transmitter on an aircraft (608, 610) of the first and second messages (M1; M2) that sent the first and second messages (M1; M2) at different times, the first and second messages (M1; M2) being first and second automatic dependent surveillance-broadcast, ADS-B, messages including compact position reporting, CPR, encoded airborne position information for the aircraft (608, 610); determining that both the first message and the second message were received by the one or more space-based receivers within a first predetermined period of time of a previous message that was used to determine a previous location of the transmitter; determining that the second message was received by the one or more space-based receivers within a second predetermined period of time from the time that the first message was received by the one or more space-based receivers; determining a first location of the transmitter identified by the encoded position included in the first message based on the previously determined location of the transmitter; determining a second location of the transmitter identified by the encoded position included in the second message based on the previously determined location of the transmitter; determining that the first location and the second location are within a first threshold distance of each other; determining an updated second location of the transmitter identified by the encoded position information included in the second message based on the first location of the transmitter; determining that the second location of the transmitter and the updated second location of the transmitter are within a second threshold distance of each other; and transmitting the updated second location of the transmitter to a subscriber system that subscribes to position reports for the transmitter. receiving, from one or more space-based receivers on one or more satellites, both a first message and a second message, the first and second messages (M1; M2) having been received by the one or more space-based receivers from, and both comprising encoded position information for, a transmitter on an aircraft (608, 610) of the first and second messages (M1; M2) that sent the first and second messages (M1; M2) at different times, the first and second messages (M1; M2) being first and second automatic dependent surveillance-broadcast, ADS-B, messages including compact position reporting, CPR, encoded airborne position information for the aircraft (608, 610); determining that both the first message and the second message were received by the one or more space-based receivers within a first predetermined period of time of a previous message that was used to determine a previous location of the transmitter; determining that the second message was received by the one or more space-based receivers within a second predetermined period of time from the time that the first message was received by the one or more space-based receivers; determining a first location of the transmitter identified by the encoded position included in the first message based on the previously determined location of the transmitter; determining a second location of the transmitter identified by the encoded position included in the second message based on the previously determined location of the transmitter; determining that the first location and the second location are within a first threshold distance of each other; determining an updated second location of the transmitter identified by the encoded position information included in the second message based on the first location of the transmitter; determining that the second location of the transmitter and the updated second location of the transmitter are within a second threshold distance of each other; and transmitting the updated second location of the transmitter to a subscriber system that subscribes to position reports for the transmitter.