In the early days aircraft accidents were only sometimes investigated by the CAB due to a shortage of resources and a limited understanding of the value of air safety investigation. However, pilots were required to notify the Department of accidents and forced landings using C.A. Form 42, below. Form 42 went through several iterations, this being possibly the earliest. Note that the space for the aircraft registration marks helpfully includes a 'G' nationality prefix, indicating this version of the form is pre-1929.

Form 42 was later replaced by a new form, the Air Safety Incident Report, Form 225.