A Supplemental Type Certificate (STC) is a means by which Aviation Authorities, including the CAA, indicate that a modification is approved.
Prior to 28 September 2003, the CAA issued most STCs in its capacity as a member of the Joint Aviation Authorities (JAA). The CAA also issued Airworthiness Approval Notes for the approval of modifications.
Since 28 September 2003, most STCs investigated by the CAA have been approved and issued by the European Aviation Safety Agency (EASA).
Information concerning STCs approved through all JAA Member States can be obtained from the JAA web site.
EASA STCs are available on the EASA web site.