The paper commences with a résumé, with statistics, of the development and extent of aviation in its various branches up to the present time. It goes on to analyse the risk incurred in each, and to discuss principles of assessment of the risk and methods of calculating extra premiums. The duties involved in the various classes of employment connected with aviation are considered, and statistics submitted dealing with accidents and casualties attending commercial aviation in Britain and in the United States. Government supervision and the regulations in force regarding the issuing of certificates of airworthiness and licences to pilots, navigators, and ground engineers are outlined. Royal Air Force flying in its different branches is dealt with and statistics of casualties are given. The answers given to a questionnaire addressed to 60 offices transacting business in Great Britain together with the extras charged for different types of risk are analysed. The question of ordinary life assurance offices reassuring aviation risks with a company specialising in such insurance is discussed. The lack of statistics is commented upon, and stress is laid on the desirability of obtaining as soon as possible reliable statistical bases for the calculation of premiums to meet the demand for cover against aviation risks, a demand which in the nature of things will increase rapidly and must be met. In an Appendix are given the recommendations of the Actuaries' Club of Toronto and a supplementary proposal form in use by a Canadian office for cases where an aviation risk is involved.