Letters to Owners and Operators (LTOs) were issued by the CAA to owners and operators of aircraft on the UK register.
They generally contain information relating to a variety of technical issues, for example, reminders of forthcoming requirements or clarification of the interpretation of Airworthiness Directives.
LTOs are not mandatory in themselves; however, they may contain significant airworthiness information received from a foreign Aviation Authority or refer to a rule or regulation that is mandatory. The following are still current, however we no longer issue LTOs, we now issue Safety Notices.