For users that do not have ADS-B Out installed.
If your aircraft is not equipped with an ADS-B Out system, ADS-B Ground Stations may broadcast your Mode-C target to other nearby ADS-B Out equipped aircraft as a TIS-B target.
If you receive that transmission it may cause your own aircraft to be displayed as a nearby TIS-B target, usually slightly behind your actual position and +/- 100-200' in altitude. After a short period of time, ForeFlight will recognize the TISB target is your aircraft and will identify it as own ship. Once identified as own ship, the TISB target will be suppressed. There is no way to remove that "ghost" target other than by turning off the Traffic layer in the drop-down menu in the upper-left corner of the Maps view.
NOTE: The TIS-B traffic broadcast from the ground stations may or may not include your N number.
For users that have ADS-B Out installed.
If you do have ADS-B Out installed, please open ForeFlight Mobile while flying and go to MORE > DEVICES > STRATUS and check the OWNSHIP ADS-B OUT. If your N-number isn't shown, or if any of the readings inside the OWNSHIP ADS-B OUT menu are red, please take a screenshot and contact firstname.lastname@example.org for suggestions on troubleshooting your ADS-B Out installation.
Note: If your ADS-B Out is based on a transponder (1090ES), you will need to have a Stratus 2 or 2S to be able to detect your own ship data.
If you have ADS-B Out and see a ghost target, it is most likely coming from the ground station that is unable to correlate your transponder position with your ADS-B Out position. This is more likely to occur during rapid maneuvering where your radar track/position doesn't keep up with your ADS-B track/position.