Gyro Error determination using a Range Lights🤗 It is not always by Celestial sights that we can determine the errors of our compass, especially the Gyro Compass. During Channeling or Harbour navigation we can utilize this method by finding the “True Bearing” of a pair of lights we call as Range Lights, go to the ECDIS object and interrogate by “pick report” function and presto you have known the TRUE BEARING of a range lights ahead of your ship. Next thing you have to do is to proceed on course