National Aviation Investigation Agency and Railway Accidents and Transportation Safety (HARSIA Greek:Εθνικός Οργανισμός Διερεύνησης Αεροπορικών και Σιδηροδρομικών Ατυχημάτων και Ασφάλειας Μεταφορών - EΟΔΑΣΑΑΜ) is the competent body for the investigation of air and rail accidents in Greece.

It is an autonomous public service of the Ministry of Infrastructure and Transport, supervised by the Minister himself.

The Board was supervised by the Ministry of Infrastructure and Transport, but its members enjoyed administrative and financial autonomy.

From 2001 to 2011, the chairman of the commission was Akrivos Tsolakis (Ακριβός Τσολάκης), the founder of the aviation safety sector in Greece.

The most famous of these were According to the European Union's Directive 2016/798 on railway safety, each member state must establish a permanent committee to investigate rail accidents and incidents.