This article is the fourth part of a series on air accident investigations. It concentrates on the protection of records gathered in aircraft accident and incident investigations. Outlined are the ways in which such materials may be used in civil, administrative and criminal proceedings. The article further presents the axiological premises and legal instruments for the protection of such records, as well as the possible grounds for their authorised disclosure and use in other proceedings. The article also points to differences as to the status of records gathered in civil aviation and state aviation investigations. Lastly, it includes remarks concerning proper implementation in Poland of international and EU rules on record protection.