Once uninstalled, look at your C:\ Drive do you see any folders marked Airnav or Airnav systems, if so manuallly delete the folder/s
Find program files, click on it look for any folders Airnav/Airnav systems
Find program files (x86) click on it and again look for any folders Airnav/Airnav systems and again delete manually
Let me know when you have done that and if you found Airnav folders
Alan