The article discusses the Cape Town Convention and its Aircraft Protocol, which establish the institution of international interest in mobile equipment (airframes, aircraft engines and helicopters). The study explains the principles of these instruments, their peculiarities, scope of application and role in the unification of international interests and in ensuring legal certainty. The consequences of the potential adoption of the Convention and the Protocol in Poland are also analysed, including the necessary amendments to civil law. Lastly, the article gives recommendations as to the accession of Poland to the Convention and the Protocol, and as to making optional declarations thereto.