Occurrence reporting is the legal duty under Reg (EU) 376/2014 to report safety events to the aviation authority: a serious injury, a near-miss with a manned aircraft, a collision, or a critical-infrastructure strike.
In Latvia a mandatory report is submitted via e.caa.gov.lv within 72 hours. For other safety events that are not mandatory to report, voluntary reporting is encouraged — every such report helps the system spot problems before they lead to an accident.