The Official Commentary on the Convention on International Interests in Mobile Equipment and Aircraft Protocol, produced by Professor Sir Roy Goode pursuant to a Resolution of the Cape Town Diplomatic Conference, was published in 2002, and quickly became the definitive guide to the Convention and the Aircraft Protocol. It was last revised in 2019. Much has changed in the intervening three years. The Convention has now been ratified by 83 States and the Protocol by 80 States, together in each case with the European Community (now the European Union). The experience of the aviation industry based on large numbers of transactions registered under the Convention and Protocol, which reached one million registrations in January 2019, has revealed a host of new issues which needed to be addressed. In addition the International Registry for aircraft objects has been progressively updated, and is the subject of new regulations which entered into force in February 2022. In this fifth edition Sir Roy has extensively revised and expanded the Official Commentary to take account of these and other important developments and to expand the analysis of a range of issues. The Official Commentary: Fifth Edition is an essential guide for all those interested or involved in aviation finance and leasing.