ED-202A / DO-326A and ED-203A / DO-356A provide guidance in addressing airworthiness security during the aircraft product life cycle from project initiation until the aircraft Type Certificate (Amended Type Certificate, Supplemental Type Certificate and Amended Supplemental Type Certificate) is issued for the aircraft type design. In addition, it includes the handover of information about the Type Design that is necessary to ensure continuing airworthiness with respect to possible information security threats.

ED-204A / DO-355A (this document) provides guidance for the following stages of the product life cycle: operation, support, maintenance, administration, and decommissioning.

Where an organization subcontracts any activities in these stages, the organization retains the responsibility for aircraft information security (for contracted maintenance providers, refer to section 1.6.3).

A forthcoming document titled “Guidance on Information Security Event Management” (ISEM) will be jointly published by EUROCAE and RTCA. This document will provide guidance for managing security incidents and events that affect aircraft safety and it will support the existing safety event management guidance. It will provide guidance for processes, assessment and disposition, data exchanges, reporting, and other concerns that need to be performed in response to information security events.

Topics in the scope of Type Certification activities that are related to operation and maintenance of the aircraft such as Instructions for Continued Airworthiness (ICA) and security guidance documents are introduced in ED-202A / DO-326A and detailed in ED- 204A / DO-355A. In such cases ED-202A / DO-326A provides references to ED- 204A / DO-355A.

This document addresses information security risks only. The security measures to mitigate these risks are not limited to technical security measures; they may also be operational or management security measures.

Apart from the classical Instructions for Continued Airworthiness that are directly related to aircraft parts and systems, this document also provides guidance on Ground Support Equipment and Ground Support Information Systems that are related to the security of aircraft information systems and data networks as illustrated in FIGURE 1. Only Airborne software that can have effect on aircraft safety are in the scope of this document

PURPOSE

This document is a resource for civil aviation authorities and the aviation industry when the operation and maintenance of aircraft and the effects of information security threats can affect aircraft safety. It deals with the activities that need to be performed in operation and maintenance of the aircraft related to information security threats.

This document gives also guidance that is related to operational and commercial effects (i.e. guidance that exceeds the safety-only effects).

ED-204A / DO-355A is a companion document to ED-202A / DO-326A “Airworthiness Security Process Specification” and ED-203A / DO-356A "Airworthiness Security Methods and Considerations" that support security in the development and modification part of the airworthiness process.

NOTE: This document was developed in the European context of the European Aviation Safety Agency (EASA) Certification Specification CS-25 "Large Aeroplanes" and the United States context of Title 14 Code of Federal Regulations (14CFR) Part 25 "Transport Category Aircraft". Tailoring of this guidance may be used in other regulatory contexts including but not limited to CS-23, CS-27, CS-29, CS-E, CS-P, Part 23, Part 27, Part 29, Part 33, and Part 35.

The most comprehensive possible area of the application of this guidance is deemed to be Large Transport Aircraft programs. However, this document does not make any assumptions about and is without prejudice to its applicability.

NOTE: The measures proposed in this document may be subject to commercial terms between DAHs and operators. It is recommended that DAHs incorporate these elements into their commercial offers, especially for service and support related topics.