The code changes remove the unused fields in the `aviation.go` file, specifically the `CallSign`, `FlightPlanID`, `Route`, `Altitude`, `Speed`, `Position`, `EmergencyIndicator`, `ReportType`, `SupplementaryInfo`, `FilingTime`, `OriginatorIndicator`, `ServiceInformation`, and `NavigationAidInfo` fields. These fields were no longer needed and were causing unnecessary clutter in the codebase. This refactor improves code cleanliness and maintainability.