EASA (European Union Aviation Safety Agency)

A systematic approach to managing safety, including the necessary organizational structures, accountabilities, policies, and procedures, as required by ICAO Annex 19. An SMS is required for service providers including airlines, approved maintenance organizations, certified aerodromes, and air navigation service providers. It consists of four pillars: safety policy and objectives, safety risk management, safety assurance, and safety promotion.

The FAA regulation that prescribes procedural requirements for the issuance of type certificates, production approvals, airworthiness certificates, and related approvals for aircraft, aircraft engines, propellers, and articles. Part 21 defines who may apply for certification, what must be shown, and how approvals are issued, amended, and maintained. It is the procedural backbone of the FAA certification system.

The FAA airworthiness standard for normal category airplanes, which encompasses what were previously classified as normal, utility, acrobatic, and commuter category airplanes. Part 23 was comprehensively restructured under Amendment 23-64 (effective August 2017) to adopt a performance-based regulatory approach with four certification levels based on passenger seating and speed. The restructured Part 23 relies on consensus standards (primarily from ASTM International) as means of compliance.

The FAA airworthiness standard containing the detailed type design requirements for transport category airplanes — typically jet-powered commercial aircraft with more than 19 passenger seats or a maximum certificated takeoff weight above 19,000 pounds. Part 25 prescribes structural, performance, flight characteristics, design and construction, powerplant, equipment, and electrical systems requirements. It is one of the most comprehensive airworthiness codes in the world.

The FAA airworthiness standard for normal category rotorcraft, covering helicopters with a maximum weight of 7,000 pounds or fewer and nine or fewer passenger seats. Part 27 prescribes the minimum design, construction, performance, and safety standards for type certification of these rotorcraft.

The FAA airworthiness standard for transport category rotorcraft, covering helicopters that exceed the Part 27 weight or passenger limits. Part 29 prescribes more stringent design and performance requirements appropriate for larger, multi-engine rotorcraft used in commercial operations, including enhanced crashworthiness, performance in engine-inoperative conditions, and more rigorous systems safety requirements.

The FAA airworthiness standard for aircraft engines, covering both reciprocating and turbine engines. Part 33 prescribes requirements for design, construction, testing, and performance including endurance testing, bird ingestion, blade containment, fire protection, and the engine's response to adverse conditions. Engine Type Certificates are issued under Part 33 independently from the airframe's TC.

The FAA airworthiness standard for propellers, establishing minimum requirements for the design, testing, and certification of aircraft propellers. Part 35 addresses structural loads, fatigue evaluation, bird impact, lightning strikes, and functional testing. Like engines, propellers receive their own Type Certificates separate from the airframe.

The FAA regulation prescribing the requirements for the issuance of repair station certificates, including the personnel, facilities, equipment, and quality system requirements necessary for certificated repair stations to perform maintenance, preventive maintenance, and alterations on aircraft, airframes, engines, propellers, appliances, and components. A Part 145 certificate is required for maintenance organizations performing work for air carriers and commercial operators.

Non-regulatory guidance documents issued by the FAA that describe acceptable means of compliance with 14 CFR requirements. Advisory Circulars are not legally binding, but they carry significant practical weight because they represent methods the FAA has pre-accepted. An applicant may propose an alternative means of compliance to an AC, but must then demonstrate that the alternative provides an equivalent level of safety and obtain FAA agreement.

The aviation safety agency of the European Union, headquartered in Cologne, Germany. EASA is responsible for the airworthiness certification of aeronautical products (type certification), the approval of design and production organisations, the development of pan-European aviation safety regulations (Implementing Rules, Certification Specifications, AMC, and GM), and the oversight of EU-wide aviation safety. EASA was established in 2002 and has progressively assumed regulatory responsibilities from national aviation authorities of EU Member States.

Regulation (EU) 2018/1139 of the European Parliament and of the Council, which is the foundational EU legislation establishing the common rules for civil aviation safety in Europe and creating EASA. It defines the essential requirements for airworthiness, environmental compatibility, pilot licensing, air operations, aerodromes, ATM/ANS, and the organizational framework for EASA and national aviation authorities. All EASA Implementing Rules and Certification Specifications derive their legal authority from this regulation.

The EASA Implementing Rule (Commission Regulation (EU) No 748/2012, Annex I) that establishes the certification procedures for aircraft, engines, propellers, parts, and appliances, as well as the requirements for design and production organisations. EASA Part 21 is functionally analogous to FAA 14 CFR Part 21 but differs in structure and process, particularly in its reliance on Design Organisation Approval (DOA) and Production Organisation Approval (POA) as the primary approval mechanisms.

The EASA Implementing Rule (Commission Regulation (EU) No 1321/2014, Annex I) establishing the requirements for the continuing airworthiness of aircraft, including the approval of continuing airworthiness management organisations (CAMO). Part-M covers airworthiness reviews, maintenance programme approval, defect reporting, and the overall framework for keeping aircraft airworthy throughout their operational life.

The EASA Implementing Rule (Commission Regulation (EU) No 1321/2014, Annex Vb) providing simplified continuing airworthiness requirements for light aircraft classified as ELA1 (European Light Aircraft with a maximum takeoff mass of 1,200 kg or less) and ELA2 (up to 2,000 kg). Part-ML offers a proportionate regulatory framework with reduced administrative burden compared to Part-M, while maintaining an adequate level of safety.

The EASA Implementing Rule (Commission Regulation (EU) No 1321/2014, Annex II) establishing the requirements for the approval of organisations engaged in the maintenance of aircraft and aircraft components. Part-145 covers personnel requirements, facilities, tooling, maintenance data, quality systems, and the privileges to issue Certificates of Release to Service (CRS). A Part-145 approval is the European equivalent of an FAA Part 145 repair station certificate.

The EASA Implementing Rule (Commission Regulation (EU) No 1321/2014, Annex Vc) establishing the requirements for organisations managing the continuing airworthiness of aircraft. A CAMO is responsible for ensuring that aircraft remain airworthy, managing maintenance programmes, arranging for maintenance to be carried out by approved organisations, and performing airworthiness reviews. Part-CAMO replaced the CAMO requirements previously contained in Part-M Subpart G.

The collective term for the EASA Implementing Rules governing air operations, contained in Commission Regulation (EU) No 965/2012. This includes Part-ORO (Organisation Requirements for air Operations), Part-ARO (Authority Requirements for air Operations), Part-CAT (Commercial Air Transport), Part-NCC (Non-Commercial operations with Complex motor-powered aircraft), Part-NCO (Non-Commercial operations with Other-than-complex aircraft), and Part-SPO (Specialised Operations).

The EASA Certification Specifications for normal-category aeroplanes, harmonized with FAA 14 CFR Part 23. CS-23 Amendment 5 adopted the restructured performance-based approach matching the FAA's Part 23 Amendment 64, using high-level safety objectives with detailed compliance methods provided through referenced consensus standards. CS-23 covers aeroplanes with a maximum seating configuration of 19 passengers and a maximum certificated takeoff mass of 8,618 kg (19,000 lb).

The EASA Certification Specifications for large aeroplanes (transport category), the European equivalent of FAA 14 CFR Part 25. CS-25 prescribes detailed airworthiness requirements for the design, construction, and performance of large aeroplanes used in commercial air transport. It is extensively harmonized with Part 25, though differences exist in specific requirements, particularly in areas such as ditching, lightning protection, and cabin safety.

The EASA Certification Specifications for small rotorcraft, the European equivalent of FAA 14 CFR Part 27. CS-27 prescribes airworthiness standards for rotorcraft with a maximum weight of 3,175 kg (7,000 lb) or less and nine or fewer passenger seats.

The EASA Certification Specifications for large rotorcraft, the European equivalent of FAA 14 CFR Part 29. CS-29 prescribes airworthiness standards for rotorcraft exceeding the CS-27 weight or passenger limitations, including multi-engine transport rotorcraft used in commercial air transport and offshore operations.

The EASA Certification Specifications for aircraft engines, the European equivalent of FAA 14 CFR Part 33. CS-E prescribes airworthiness standards for the type certification of turbine and reciprocating engines, covering design and construction, endurance testing, ingestion tests, and operational characteristics.

The EASA Certification Specifications for propellers, the European equivalent of FAA 14 CFR Part 35. CS-P prescribes airworthiness standards for the type certification of propellers, covering structural design, fatigue evaluation, functional tests, and environmental considerations.

The EASA Certification Specifications containing the European Technical Standard Orders (ETSOs), which define minimum performance standards for specified articles (components, equipment, parts). An ETSO authorization issued under Part 21 Subpart O certifies that an article meets the applicable ETSO standard. CS-ETSO indexes are largely harmonized with FAA TSOs, with the ETSO number typically corresponding to the equivalent TSO number (e.g., ETSO-C151 corresponds to TSO-C151).

Non-binding standards adopted by EASA to facilitate compliance with the Implementing Rules and Certification Specifications. Acceptable Means of Compliance (AMC) describe methods that EASA has pre-accepted for demonstrating compliance; an applicant following an AMC is presumed to meet the underlying requirement. Guidance Material (GM) provides explanatory and interpretive information to help stakeholders understand the intent of regulations. Neither AMC nor GM are legally binding.

An approval issued by EASA under Part 21 Subpart J to an organisation that has demonstrated its capability to design or make changes to type design for aircraft products. A DOA holder is granted privileges to approve minor changes and minor repairs without prior EASA involvement, and to submit major changes and major repairs for EASA approval with reduced EASA direct involvement. The DOA is central to the EASA certification system as it enables approved design organisations to self-manage significant portions of the compliance demonstration process.

An approval issued by EASA under Part 21 Subpart G to an organisation that has demonstrated its capability to manufacture products, parts, and appliances in conformity with the approved type design data. A POA holder is granted the privilege to issue EASA Form 1 authorised release certificates for new parts and to make statements of conformity for complete aircraft. The POA is the European equivalent of the FAA Production Certificate.

A formal document used by EASA during a certification project to define, discuss, and resolve specific certification issues. CRIs serve multiple purposes: they may propose special conditions, establish interpretive material, document means of compliance agreements, or address specific technical issues that arise during the certification process. CRIs are the EASA counterpart to FAA Issue Papers and are a primary mechanism for communication between EASA and the applicant on certification matters.

A legally binding rule issued by a governmental authority under legislative power that prescribes mandatory requirements. In aviation, regulations are codified law that certificate holders and applicants must comply with. Violation of a regulation can result in enforcement action, including certificate suspension or revocation, civil penalties, or criminal prosecution. Regulations define the 'what' — the mandatory requirements — while standards and guidance material describe the 'how.'

Non-binding documents issued by aviation authorities or standards bodies that provide explanatory, interpretive, or advisory information to assist in understanding and complying with regulations. Guidance material does not create legal obligations; rather, it describes methods, processes, or interpretations that the issuing authority considers acceptable or helpful. Examples include FAA Advisory Circulars, EASA Acceptable Means of Compliance (AMC), EASA Guidance Material (GM), and TCCA Advisory Circulars.

The formal process by which an aviation authority develops, proposes, consults on, and adopts new or amended regulations. In the United States, FAA rulemaking follows the Administrative Procedure Act (APA) notice-and-comment process. EASA rulemaking follows a structured process involving Notices of Proposed Amendment (NPA), public comment, and adoption of Implementing Rules or Certification Specifications. Rulemaking is the mechanism through which regulatory requirements evolve in response to safety data, technological developments, and harmonization needs.

A formal public notice published by the FAA in the Federal Register that proposes a new regulation or an amendment to an existing regulation. An NPRM describes the proposed rule, its legal basis, the problem it addresses, and its expected impact. The NPRM opens a public comment period (typically 60-90 days) during which any person may submit comments, data, or arguments. The FAA must consider all comments before issuing a final rule. EASA's equivalent is the Notice of Proposed Amendment (NPA).

A method, process, or technical approach that the certifying authority has determined to be adequate for demonstrating compliance with a specific airworthiness requirement. Each regulation in the certification basis requires one or more means of compliance (MOC). Acceptable means may be codified in guidance material (FAA ACs, EASA AMC) or may be proposed by the applicant and agreed by the authority during the certification project. The selection and agreement of means of compliance is a foundational step in the certification process.

The process by which a civil aviation authority evaluates and formally approves that a product, part, appliance, organisation, or person meets applicable regulatory requirements. In the context of type certification, it is the comprehensive evaluation of a type design against the applicable airworthiness standards by the authority having jurisdiction over the applicant (the State of Design authority). Certification results in the issuance of a formal approval document such as a Type Certificate, STC, or organisation approval.

The process by which a civil aviation authority evaluates a product that has already been certified by a foreign authority and determines whether it meets the importing authority's own regulatory requirements. Validation does not repeat the full certification process; instead, it leverages the certification work performed by the exporting authority while the validating authority evaluates areas of concern, differences in requirements, and issues specific to its jurisdiction. The scope and process of validation are typically governed by bilateral agreements (BASAs).

An approval issued by the aviation authority that authorizes a specific operator or certificate holder to conduct certain types of operations or use specific equipment capabilities. Operational approvals address the 'who may operate' and 'under what conditions' questions, as opposed to airworthiness approvals which address the 'is the product safe by design' question. Examples include ETOPS authorization, RVSM approval, Cat II/III approach authorization, and LVO (Low Visibility Operations) approval.

The complete technical definition of a product, including all drawings, specifications, and data that define the configuration and design features of the product, its components, and the information necessary to define the airworthiness, noise, fuel venting, and exhaust emission characteristics of the product. The type design is the 'master definition' against which all produced articles must conform. It includes the drawings and specifications necessary to define the structural strength, performance, operating limitations, and all other design attributes of the product.

The set of processes, activities, and arrangements that ensure an aircraft continues to meet its approved type design requirements and remains in a condition for safe operation throughout its operational life. Continued airworthiness encompasses the TC holder's obligation to provide maintenance and operational instructions (Instructions for Continued Airworthiness — ICA), the operator's responsibility to maintain the aircraft per the approved maintenance program, the authority's mandatory corrective actions (Airworthiness Directives), and the systematic monitoring of the in-service fleet.

A formal approval issued by the certifying authority that confirms a product's type design complies with the applicable airworthiness requirements. A TC is issued for aircraft, aircraft engines, and propellers upon successful completion of the type certification process, which involves demonstrating compliance with every applicable regulation in the certification basis through analysis, test, and inspection. The TC defines the approved type design, operating limitations, applicable regulations, and conditions and limitations.

A modification to an existing Type Certificate that reflects a major change in the type design. An Amended TC is sought when the TC holder (or a person with proper licensing agreements) proposes changes that are significant enough to be classified as a major change but do not warrant a new, separate TC. The certification basis for an ATC typically includes the original TC certification basis plus any additional requirements triggered by the nature and extent of the change, as determined by the authority.

A design approval issued to an applicant who is not the TC holder, authorizing a major modification to an existing type-certificated product. An STC grants the holder the right to modify the product as described in the STC design data and to produce the modification components (or have them produced). The STC holder becomes responsible for the continued airworthiness of the modification, including providing ICAs, addressing unsafe conditions related to the modification, and ensuring compatibility with the underlying TC.

The classification of a change to a type design as either major or minor, which determines the approval process and regulatory path. A major change is one that has an appreciable effect on the weight and balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting the airworthiness of the product, or that is not done according to accepted practices or cannot be done by elementary operations. A minor change is one that does not meet the criteria for major. Major changes require more extensive compliance demonstration and authority involvement.

A minimum performance standard for specified articles (materials, parts, processes, appliances, or components) issued by the FAA under 14 CFR Part 21, Subpart O. A TSO defines the minimum performance criteria that an article must meet, typically by referencing industry standards (such as RTCA DO- documents or SAE standards). A TSO Authorization (TSOA) is issued to a manufacturer who demonstrates that their article meets the applicable TSO standard, authorizing them to produce and mark the article as TSO-approved.

A combined design and production approval issued by the FAA under 14 CFR Part 21, Subpart K, that authorizes a manufacturer to produce and sell replacement or modification parts for installation on type-certificated products. A PMA holder must demonstrate that the part meets the applicable airworthiness requirements (design approval) and that the manufacturing quality system can consistently produce conforming parts (production approval). PMA parts are approved for installation as alternatives to original equipment manufacturer (OEM) parts.

The formal authorization to perform a specific repair on a type-certificated product. Repairs are classified as major or minor, with major repairs requiring approved data from an authorized source before the work can be performed. Sources of approved repair data include the TC/STC holder's repair documentation, DER-approved repair designs, FAA-approved repair data, and repair data in the manufacturer's structural repair manual (SRM). The repair must restore the product to at least its original or properly altered condition.

An FAA approval issued under 14 CFR Part 21, Subpart F, that authorizes a manufacturer to produce duplicate products (aircraft, engines, propellers) under an approved type design without the FAA performing individual article conformity inspections. A PC holder must maintain a quality system that ensures each product conforms to the approved type design and is in a condition for safe operation. The PC is the FAA's primary production approval for complete products.

The standard FAA form used to certify that a new or repaired/overhauled article (part, component, appliance) has been manufactured, inspected, tested, or maintained in accordance with approved data and is approved for return to service. An 8130-3 is issued by entities authorized by the FAA, including Production Certificate holders, PMA holders, TSO Authorization holders, repair stations, and FAA designees. It serves as both an airworthiness approval tag and an export airworthiness approval when used for international trade.

The standard EASA form used to certify that a new, repaired, or overhauled article has been manufactured or maintained in accordance with approved data and is released for service. EASA Form 1 is issued by organisations approved under EASA Part 21 (POA holders for new production) or EASA Part 145 (maintenance organisations for maintained articles). It serves as the primary airworthiness release document in the European system and is recognized internationally under bilateral agreements.

The person or organization that applies to the certifying authority for a design approval (Type Certificate, STC, TSOA, or other approval). The applicant bears the responsibility for demonstrating compliance with all applicable airworthiness requirements and for providing the authority with the data, test results, and analyses necessary to support findings of compliance. The applicant must have the technical capability and resources to complete the certification program.

The government agency or body responsible for evaluating and approving (or rejecting) an applicant's compliance showing and issuing the certification approval. The certifying authority is typically the civil aviation authority of the State of Design. The authority establishes the certification basis, agrees on means of compliance, evaluates compliance data, conducts audits and inspections, makes findings of compliance, and ultimately issues or denies the requested approval.

The group of authority personnel (and designees, where applicable) assigned to manage and execute a specific certification project. The certification team typically includes a project manager (or project officer), technical specialists in relevant disciplines (structures, systems, flight test, propulsion, electrical, software, human factors), and manufacturing inspectors. The team evaluates the applicant's compliance showing, conducts audits and conformity inspections, and makes the findings that support certificate issuance.

The complete set of airworthiness requirements (regulations at specific amendment levels), special conditions, exemptions, and equivalent safety findings that an applicant must comply with to obtain a design approval. The certification basis is established by the certifying authority early in the certification project and is documented formally. For a new TC, the certification basis is determined by the applicable regulations in effect on the date of the TC application, plus any later amendments elected by the applicant or required by the authority.

Additional airworthiness requirements prescribed by the certifying authority when the existing regulations do not contain adequate or appropriate safety standards for a particular design feature, technology, or operational use that is novel or unusual. Special conditions have the same legal force as the regulations themselves and become part of the certification basis for the specific project. They are used when the existing code was not written to address the specific design characteristic or technology being proposed.

A formal authorization granted by the certifying authority that allows an applicant to deviate from a specific regulatory requirement. An exemption relieves the applicant from the obligation to comply with a specific regulation, subject to conditions and limitations that ensure an adequate level of safety is maintained. Exemptions are typically time-limited and must be justified by demonstrating that compliance is impractical or that the exemption does not compromise safety.

A formal determination by the certifying authority that an alternative means of compliance, while not literally meeting the text of a specific airworthiness requirement, provides a level of safety equivalent to that intended by the requirement. An ELOS finding allows the applicant to use compensating factors, design features, or operational limitations that achieve the same safety objective through different means. ELOS findings become part of the certification basis for the specific project.

The process of identifying and agreeing with the certifying authority on the specific methods (analysis, test, inspection, demonstration, simulation, or a combination) that will be used to show compliance with each applicable airworthiness requirement in the certification basis. Means of compliance selection is a collaborative process between the applicant and the authority, typically conducted early in the certification project and documented in the certification plan and compliance checklists.

A program-level document prepared by the applicant and agreed with the certifying authority that describes the overall strategy, schedule, and approach for completing the certification project. The certification plan typically includes a description of the product and proposed changes, the certification basis, the means of compliance for each requirement area, the organizational structure and responsibilities, the schedule and milestones, the data submittal plan, and any known certification risks or issues. It serves as the project roadmap.

The practice of leveraging existing compliance data, test results, analyses, and approval findings from a prior certification project to support a new or amended certification project, thereby reducing the scope of new compliance work required. Certification credit may be granted when a new design is sufficiently similar to an already-certified design that the existing compliance evidence remains valid and applicable. The applicant must demonstrate the basis for claiming credit, including the similarity of the designs, the applicability of the prior compliance data, and any differences that require additional substantiation.

An individual appointed by the FAA Administrator under 14 CFR 183.29 to act as a representative of the Administrator in examining, testing, and inspecting aircraft, aircraft engines, propellers, appliances, and accessories, and to issue approvals on behalf of the FAA for engineering data, including type design data, approved data packages, and related technical reports. DERs supplement the FAA's certification workforce by providing engineering findings of compliance.

An individual designated by the FAA under 14 CFR 183.33 to perform examination, inspection, and testing services necessary to the issuance of airworthiness certificates. DARs may be authorized for manufacturing (DAR-F) or maintenance (DAR-T) functions. A manufacturing DAR inspects new or modified aircraft and issues original or amended airworthiness certificates, export airworthiness approvals, and related documentation. A maintenance DAR performs inspections and may return aircraft to service after major repairs or alterations.

An FAA authorization granted under 14 CFR Part 183, Subpart D, that allows an organization to perform specified certification functions on behalf of the FAA. Unlike individual designees (DERs and DARs), an ODA is an organizational authorization: the company itself receives the authority, and it manages internal unit members who perform the delegated functions. The ODA is managed through an ODA Unit that includes an ODA Administrator, ODA Unit Members (engineers, pilots, inspectors), and supporting procedures documented in the ODA Procedures Manual.

An EASA approval granted under Part 21, Subpart J, to an organisation that has demonstrated its capability to design or modify aeronautical products in compliance with applicable airworthiness requirements. The DOA holder is granted privileges to approve certain design data without direct EASA involvement, including approval of minor changes (under Part 21.A.95) and minor repairs (under Part 21.A.431B). For major changes and major type certificate activities, the DOA prepares compliance data and its CVEs verify compliance, but EASA retains final type certificate approval authority.

An EASA approval granted under Part 21, Subpart G, to an organisation that has demonstrated its capability to manufacture aeronautical products, parts, and appliances in conformity with applicable design data. The POA holder operates a production quality system, performs conformity inspections, and is authorized to issue EASA Form 1 authorized release certificates for parts and appliances produced under the approval. The POA must maintain coordination with the Design Approval Holder (DAH) to ensure manufacturing conforms to the current approved design.

An engineer within an EASA Design Organisation Approval (DOA) who is authorized by the DOA holder to verify that design data demonstrates compliance with applicable airworthiness requirements. CVEs are appointed by the Head of Design Office and must possess the necessary competence, experience, and authority to perform compliance verification independently. They review compliance documents, test reports, analyses, and supporting data, and they sign compliance verification reports confirming that the evidence substantiates compliance with each applicable requirement.

The boundaries placed on designated individuals and organizations regarding the types of certification activities they may perform, and the requirement that those performing delegated functions exercise independent technical judgment free from undue organizational pressure. Delegation limits are documented in appointment letters (for DERs), authorization letters (for ODAs), or the Design Organisation Handbook (for DOAs). Independence means that the person making a finding of compliance or airworthiness determination must not be subject to commercial, schedule, or management pressures that could compromise the integrity of their technical judgment.

A document issued by an authorized person or organization that certifies a part, component, or appliance has been manufactured, inspected, and/or tested in accordance with approved design data and is in a condition for safe operation or installation. The specific form depends on the jurisdiction: FAA Form 8130-3 (Authorized Release Certificate / Airworthiness Approval Tag), EASA Form 1 (Authorized Release Certificate), or TCCA equivalent documentation. The authorized release certificate attests to conformity with design data and condition for safe operation, but it is not an approval of the design itself.

The categorization of failure conditions by their severity of effect on the aircraft and its occupants. Five classifications are defined: (1) Catastrophic — failure conditions that would result in multiple fatalities, usually with the loss of the aircraft; (2) Hazardous (also called Severe-Major) — failure conditions that would reduce the capability of the aircraft or the ability of the crew to cope with adverse operating conditions to the extent that there would be a large reduction in safety margins or functional capabilities, physical distress or higher workload such that the crew could not be relied upon to perform their tasks accurately or completely, serious or fatal injury to a relatively small number of occupants; (3) Major — failure conditions that would reduce the capability of the aircraft or the ability of the crew to cope with adverse operating conditions to the extent that there would be a significant reduction in safety margins or functional capabilities, significant increase in crew workload or in conditions impairing crew efficiency, or discomfort to occupants possibly including injuries; (4) Minor — failure conditions that would not significantly reduce aircraft safety and that involve crew actions well within their capabilities, including slight reduction in safety margins, slight increase in workload, or some physical discomfort to occupants; (5) No Safety Effect — failure conditions that have no effect on safety.

The quantitative and qualitative targets that a design must meet for each failure condition classification. For transport category aircraft under 14 CFR/CS 25.1309, the quantitative probability targets are: Catastrophic failure conditions must be extremely improbable (typically interpreted as a probability of occurrence on the order of 10^-9 or less per flight hour); Hazardous failure conditions must be extremely remote (on the order of 10^-7 per flight hour); Major failure conditions must be remote (on the order of 10^-5 per flight hour); Minor failure conditions must be probable (no specific numerical threshold, but must be shown to be acceptable). In addition to probability targets, qualitative objectives apply: no single failure should lead to a catastrophic failure condition, and the crew must be able to detect and manage failure conditions through appropriate annunciation and procedures.

A structured argument, supported by a body of evidence, that provides a compelling, comprehensible, and valid case that a system is acceptably safe for a given application in a given operating environment. The safety case integrates all safety-related evidence — including safety analyses (FHA, PSSA, SSA), design data, test results, process evidence (development assurance), and operational considerations — into a coherent narrative demonstrating that safety objectives are met. The safety case concept is used explicitly in some regulatory frameworks and implicitly in others where the certification evidence package serves the same function.

An SAE Aerospace Recommended Practice that provides guidelines for the development of civil aircraft and systems, considering the overall aircraft operating environment and functions. ARP4754B defines the aircraft and system development process, including planning, requirements capture, design, implementation, integration, verification, validation, configuration management, quality assurance, and certification liaison. It establishes the framework for assigning Development Assurance Levels (DALs) to functions, systems, and items based on failure condition severity, and describes the integral processes (safety assessment, requirements management, validation) that support development assurance.

An SAE Aerospace Recommended Practice that provides guidelines and methods for conducting the safety assessment process on civil airborne systems and equipment. ARP4761A describes the Functional Hazard Assessment (FHA), Preliminary System Safety Assessment (PSSA), System Safety Assessment (SSA), and Common Cause Analysis (CCA) processes, along with detailed guidance on specific analysis methods including Fault Tree Analysis (FTA), Failure Modes and Effects Analysis (FMEA), Markov Analysis, Dependency Diagrams, and other techniques used to demonstrate compliance with 25.1309 and equivalent regulations.

The primary guidance document used by certification authorities and industry for the development of airborne software. DO-178C defines the objectives, activities, and design considerations for software that performs functions in airborne systems and equipment. It establishes a framework of software lifecycle processes — planning, requirements, design, coding, integration, verification, configuration management, quality assurance, and certification liaison — with objectives that scale based on the software level (DAL A through E). DO-178C replaced DO-178B in 2011, adding technology-specific supplements and clarifying objectives.

The primary guidance document for design assurance of airborne electronic hardware, including complex programmable hardware devices such as FPGAs, ASICs, PLDs, and complex COTS components. DO-254 defines a hardware design lifecycle similar in structure to DO-178C's software lifecycle, including planning, requirements capture, conceptual design, detailed design, implementation (synthesis, place-and-route), verification, configuration management, and process assurance. The objectives scale based on the hardware Design Assurance Level (DAL A through E). DO-254 applies specifically to complex electronic hardware; simple hardware items may be addressed through conventional quality assurance processes.

The standard that defines environmental test conditions and procedures for airborne equipment. DO-160G specifies the environmental tests that equipment must pass to demonstrate it can function correctly in the aircraft environment, including tests for temperature (altitude, temperature variation, thermal shock), vibration (random, sinusoidal), humidity, shock, power input (normal and abnormal power conditions), voltage spike, audio frequency conducted susceptibility, induced signal susceptibility, radio frequency susceptibility (radiated and conducted), radio frequency emission, lightning (direct and indirect effects), icing, fluid susceptibility, sand and dust, fungus, salt spray, magnetic effect, fire/flammability, and waterproofness.

A standard that establishes requirements for the processing of aeronautical data to ensure data quality and integrity throughout the data chain. DO-200B defines a framework for data quality requirements including accuracy, resolution, integrity, traceability, timeliness, and completeness. It applies to organizations that originate, process, or distribute aeronautical data used in airborne systems, including navigation databases, terrain databases, and obstacle databases. The standard requires data quality assurance processes, including independent verification, configuration management, and traceability from data source to end use.

A standard that defines the airworthiness security process for aircraft systems, addressing intentional unauthorized electronic interactions (IUEI) — cybersecurity threats — that could affect the safety of the aircraft. DO-326A establishes a security risk assessment process that evaluates how threat agents could exploit vulnerabilities in aircraft systems to cause failure conditions. The standard defines security objectives commensurate with safety impact: systems whose compromise could lead to catastrophic failure conditions require the most rigorous security measures. DO-326A integrates security considerations into the existing safety assessment framework of ARP4754B and ARP4761A.

The EUROCAE publication of the software certification guidance document that is technically identical to RTCA DO-178C. ED-12C is published by EUROCAE (European Organisation for Civil Aviation Equipment) and is the European designation for the same standard. ED-12C is referenced by EASA through AMC 20-115D as the acceptable means for airborne software development assurance in the European regulatory framework. All technical content, objectives, tables, and appendices are identical to DO-178C.

The EUROCAE publication of the hardware design assurance guidance document that is technically identical to RTCA DO-254. ED-80 is referenced by EASA as the acceptable means for complex airborne electronic hardware design assurance. All technical content, objectives, and guidance are identical to DO-254.

The EUROCAE publication of the environmental test standard that is technically identical to RTCA DO-160G. ED-14G defines the same environmental test conditions, procedures, and categories as DO-160G. It is referenced in EASA certification specifications, ETSOs, and certification programs as the accepted environmental qualification standard for airborne equipment.

The EUROCAE publication of the systems development assurance guidance that is technically aligned with SAE ARP4754B. ED-79B provides guidelines for the development of civil aircraft and systems, addressing the same topics as ARP4754B: system development processes, development assurance level assignment, safety assessment integration, validation, verification, and configuration management. ED-79B is referenced by EASA in AMC 20-152A.

The EUROCAE publication of the safety assessment guidelines that is the European equivalent of SAE ARP4761A. ED-135 provides guidelines and methods for conducting the safety assessment process, including FHA, PSSA, SSA, and CCA, as well as detailed guidance on analysis methods such as FTA, FMEA, Markov Analysis, and Dependency Diagrams. ED-135 is referenced by EASA in certification specifications and acceptable means of compliance.

Certification liaison is the ongoing communication between the applicant and the certification authority throughout the software lifecycle. Stages of Involvement (SOIs) are structured review points at which the certification authority evaluates the software development and verification progress. The FAA defines four SOIs for software: SOI #1 (Planning Review) — reviews the PSAC, plans, and standards before significant development begins; SOI #2 (Development Review) — reviews requirements, design, and initial development outputs; SOI #3 (Verification Review) — reviews verification results, including test results, coverage analysis, and traceability; SOI #4 (Final Review) — reviews the Software Accomplishment Summary, open problem reports, and the complete lifecycle data package. SOIs may also include audits of the development and verification environment.

Electronic hardware items (circuit board assemblies, components, programmable logic devices, and associated wiring) that perform functions in airborne systems or equipment. AEH is distinct from software and is subject to its own assurance processes under DO-254/ED-80.

The primary planning document for DO-254 hardware certification, establishing the agreement between the applicant and the certification authority on the hardware design assurance approach. The PHAC identifies the hardware items requiring design assurance, their design assurance levels, the lifecycle processes to be applied, the standards and guidance to be followed, and any deviations or alternative methods of compliance.

The high-level radio frequency electromagnetic environment produced by ground-based and shipboard radar, broadcast transmitters, satellite communication stations, and other high-power RF sources that can illuminate aircraft during flight or ground operations. The HIRF environment can induce currents in aircraft wiring sufficient to cause upset or damage to avionics equipment. Regulatory requirements for HIRF protection are defined in 14 CFR 25.1317 (FAA) and CS-25.1317 (EASA).

A legally enforceable regulation issued by an airworthiness authority that mandates inspection, modification, operational limitation, or replacement actions on an aircraft, engine, propeller, or appliance to correct an unsafe condition. Compliance with an AD is mandatory for continued operation of the affected product. ADs are issued when an unsafe condition exists or is likely to exist in other products of the same type design.

The set of documents provided by the type certificate holder that contains the information necessary for an operator to maintain an aircraft, engine, or appliance in an airworthy condition throughout its operational life. ICAs include the maintenance manual, overhaul manual, structural repair manual, illustrated parts catalogue, wiring diagram manual, and scheduled maintenance requirements, as well as airworthiness limitations that are regulatory-approved and mandatory.

14 CFR Part 43 (FAA) defines the standards and rules for maintenance, preventive maintenance, rebuilding, and alteration of aircraft, engines, propellers, and appliances. It establishes who is authorized to perform maintenance, what standards must be followed, and what records must be kept. Equivalent regulations exist in EASA (Part-M and Part-ML for continuing airworthiness management, Part-145 for maintenance organizations) and TCCA (CAR 571 for maintenance requirements, CAR 573 for approved maintenance organizations).

A maintenance facility certificated by the aviation authority to perform maintenance, preventive maintenance, and alterations on aircraft, engines, propellers, and appliances. In the FAA system, these are certificated under 14 CFR Part 145 as Repair Stations. In EASA, they are approved under Part-145 as Maintenance Organisations. In TCCA, they are approved under CAR 573 as Approved Maintenance Organizations (AMOs).

An organisation approved by EASA (under Part-M Subpart G, or Part-CAMO for air carrier aircraft) to manage the continuing airworthiness of aircraft and their components. The CAMO is responsible for ensuring that all required maintenance is planned, scheduled, and accomplished, that the aircraft configuration is properly managed, and that the aircraft remains in compliance with its approved maintenance programme, ADs, and airworthiness limitations throughout its operational life.

The Master Minimum Equipment List (MMEL) is a document established by the type certificate holder and approved by the certification authority that identifies equipment and instruments that may be inoperative for dispatch under specified conditions and limitations, while still maintaining an acceptable level of safety. The Minimum Equipment List (MEL) is the operator-specific document, derived from the MMEL, tailored to the operator's specific aircraft configuration, operations, and maintenance capability, and approved by the operator's national aviation authority.

The systematic process of tracking and managing the physical configuration of each aircraft and its components throughout the operational life, ensuring that the aircraft conforms to its approved type design (including all incorporated modifications, service bulletins, and airworthiness directives) and that the configuration is accurately documented in the aircraft's continuing airworthiness records.

The process of recording and monitoring the current modification status of each aircraft and its individual components, including which service bulletins have been incorporated, which ADs have been complied with, and the current part number, serial number, and software version of each installed item. Modification status tracking ensures that each aircraft's physical configuration is accurately known and documented at all times.

The regulatory framework that governs the certification of aircraft, engines, propellers, and articles (parts and appliances), including procedures for type certificates, supplemental type certificates, production approvals, airworthiness certificates, and export airworthiness approvals. Part 21 is the foundational regulation that defines how a product progresses from design approval to production and operational service.

The mechanisms by which certification authorities delegate specific approval privileges to qualified individuals or organizations, enabling them to perform certain certification activities on behalf of the authority. Delegation reduces the authority's direct workload while maintaining safety oversight. Each jurisdiction has evolved different delegation structures reflecting its regulatory philosophy.

A Technical Standard Order (TSO) is a minimum performance standard issued by the certification authority that an article (equipment or appliance) must meet in order to receive a TSO Authorization (TSOA). A TSOA certifies that the article meets the applicable TSO performance standard and may be installed on any applicable aircraft. The FAA issues TSOs under 14 CFR Part 21 Subpart O. EASA issues European Technical Standard Orders (ETSOs) under Part 21 Subpart O. TCCA issues Canadian Technical Standard Orders (CAN-TSOs).

A design approval issued for a major modification to the type design of an existing type-certificated product (aircraft, engine, or propeller). The STC approves the design change and the associated installation instructions, maintenance data, and, where applicable, flight manual supplements. The STC holder has the authority to produce the modification kit and the obligation to provide Instructions for Continued Airworthiness.

Non-mandatory guidance material published by certification authorities that provides acceptable means of compliance with the regulatory requirements, explanatory material, and recommended practices. While not legally binding, guidance documents describe methods that the authority has pre-accepted as demonstrating compliance with the applicable rules, and deviation from them typically requires coordination with the authority to establish an equivalent alternative means.

Formal mechanisms used by certification authorities to document and track specific certification issues, concerns, or special conditions that arise during a certification project and require resolution between the applicant and the authority. These instruments capture the authority's position on a compliance matter, the agreed means of compliance, and the resolution.

The authorized release certificate that accompanies an aircraft part, component, or appliance to attest that the article has been manufactured, inspected, and/or tested in accordance with approved data and is in a condition for safe installation. The release certificate provides the traceability between the physical article and its approved design, and it is the primary document used by maintenance organizations to determine whether an article is eligible for installation on an aircraft.