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Human Factors Policies Related to Transport Airplane Certification


Provide limited exposure to the regulations related to human factors issues ... caution lights (lights indicating the possible need for future corrective action) ... – PowerPoint PPT presentation

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Title: Human Factors Policies Related to Transport Airplane Certification

Human Factors Policies Related to Transport
Airplane Certification
Loran Haworth FAA Transport Airplane Directorate
Purpose of this Briefing
  • Federal Aviation Administration (FAA)
    Certification Service
  • Provide limited exposure to the regulations
    related to human factors issues
  • Introduce the human factors policies that have
    been published
  • Discuss how human factors issues can be covered
    explicitly in a certification plan
  • Discuss some of the issues associated with
    methods of compliance for regulations related to
    human factors
  • Bilateral Cooperation

The Aircraft Certification Service Mission
  • Promote Aviation Safety by
  • Prescribing minimum standards for aeronautical
  • Administering Certification Programs to assure
    compliance with prescribed safety standards
  • Monitoring safety performance and acting to
    provide continued operational safety of aircraft
  • Working with other countries to improve safety
    internationally and harmonize certification
    standards and practices

Aircraft Certification Service Accountable
Headquarters Policy Offices (Standards Staff)
Role of Accountable Directorate
  • Special Policy Office
  • Develops policy for particular category of
    aircraft or component
  • Established where Aircraft Certification (AIR)
    has depth of experience
  • Responsibility for specific bilateral partner
  • Focal point for resolution of issues, information
    and formal bilateral meetings

Unofficial Definition of Human Factors for
Aircraft Certification
  • The application of scientific theory, principles,
    data and methods
  • about human abilities, limitations, and other
  • to the establishment of minimum safety-related
    design requirements for flight crew interfaces,
    tasks, and procedures,
  • and then ensuring that those requirements are
    met,in order to promote overall system
    performance and safety.
  • This is nothing magical - there are a number of
    existing rules that attempt to account for the
    needs of the pilot

Classic HF Rules?
  •  25.777(b) The direction of movement of cockpit
    controls must meet the requirements of Sec.
    25.779. Wherever practicable, the sense of motion
    involved in the operation of other controls must
    correspond to the sense of the effect of the
    operation upon the airplane or upon the part
    operated. Controls of a variable nature using a
    rotary motion must move clockwise from the off
    position, through an increasing range, to the
    full on position.
  •  25.781 Cockpit control knobs must conform to
    the general shapes (but not necessarily the exact
    sizes or specific proportions) in the following

Human Factors Rules
  • There are a number of Part 25 regulations that
    directly relate to human factors issues, e.g.
  • Workload, Fatigue, Minimum Crew (25.771, 25.1523,
    Appendix D)
  • Intended function (25.1301)
  • Lighting (25.1321)
  • Error associated with responding to system
    failures (25.1309)
  • Control operation and arrangement, reach
    clearance (25.777)
  • Human factors issues cut across the entire flight
  • Human factors issues often require subjective

Some General HF Requirements
  • 25.771a Each pilot compartment and its
    equipment must allow the minimum flight crew to
    perform their duties without unreasonable
    concentration or fatigue.
  • 25.771e Vibration and noise characteristics of
    cockpit equipment may not interfere with safe
    operation of the airplane.
  • 25.773a(1) Each pilot compartment must be
    arranged to give the pilots sufficiently
    extensive, clear, and undistorted view, to enable
    them to safely perform any maneuvers within the
    operating limitations of the airplane, including
    takeoff, approach, and landing.
  • 25.773a(2) Each pilot compartment must be free
    of glare and reflections that could interfere
    with the normal duties of the minimum flight
  • 25.777a Each cockpit control must be located to
    provide convenient operation and to prevent
    confusion and inadvertent operation.

Some General HF Requirements (continued)
  • 25.777c The controls must be located and
    arranged, with respect to the pilots seats, so
    that there is full and unrestricted movement of
    each control without interference from the
    cockpit structure or the clothing of the minimum
    flight crew when any member of this flight crew,
    from 52 to 63 in height, is seated with the
    seat belt and shoulder harness fastened.
  • 25.1301a Each item of installed equipment must
    be of a kind and design appropriate to its
    intended function.
  • 25.1309b(3) Systems, controls, and associated
    monitoring and warning means must be designed to
    minimize crew errors which could create
    additional hazards.
  • 25.1321a Each flight, navigation, and
    powerplant instrument for use by any pilot must
    be plainly visible to him from his station with
    the minimum practicable deviation from his normal
    position and line of vision when he is looking
    forward along the flight path.

Some General HF Requirements (continued)
  • 25.1321e If a visual indicator is provided to
    indicate malfunction of an instrument, it must be
    effective under all probable cockpit lighting
  • 25.1523. The minimum flight crew must be
    established so that it is sufficient for safe
    operation, considering
  • a) The workload on individual crewmembers
  • b) The accessibility and ease of operation of
    necessary controls by the appropriate
    crewmember, and
  • c) The kind of operation authorized under
    25.1525. The criteria used in making the
    determinations required by this section are set
    forth in Appendix D
  • 25.1543b Each instrument marking must be
    clearly visible to the appropriate crewmember.

System - Specific HF Requirements
  • 25.785g Each seat at a flight deck station must
    have a restraint system that permits the flight
    deck occupant, when seated with the restraint
    system fastened, to perform all of the occupants
    necessary flight deck functions.
  • 25.785L The forward observers seat must be
    shown to be suitable for use in conducting the
    necessary enroute inspections.
  • 25.1141a Power plant controls each control
    must be located so that it cannot be
    inadvertently operated by persons entering,
    leaving, or moving normally in the cockpit.

System - Specific HF Requirements (cont.)
  • 25.1322 If warning, caution, or advisory
    lights are installed in the cockpit, they must,
    unless otherwise approved by the Administrator,
    be -
  • Red, for warning lights (lights indicating a
    hazard which may require immediate corrective
  • Amber, for caution lights (lights indicating the
    possible need for future corrective action)
  • Green for safe operation lights and
  • Any other color, including white, for lights not
    described in paragraphs (a) through (c) of this
    section, provided the color differs sufficiently
    from the colors prescribed in paragraphs (a)
    through (c) of this section to avoid possible

System - Specific HF Requirements (continued)
  • 25.1357d If the ability to reset a circuit
    breaker or replace a fuse is essential to safety
    in flight, that circuit breaker or fuse must be
    located and identified so that it can be readily
    reset or replaced in flight.
  • 25.1381a(2) The instrument lights must be
    installed so that (ii) no objectionable
    reflections are visible to the pilot.

Limited Human Factors Guidance
  • There is guidance material for only a few of the
    HF rules
  • AC 25-7A Flight Test Guide for Certification of
    Transport Airplanes
  • AC 25-11 Transport Category Airplane Electronic
    Display Systems
  • AC 25.1523-1 Minimum Flight Crew
  • AC 25.773-1 Pilot Compartment View Design
  • AC 20-88A Guidelines on the Marking of Aircraft
    Powerplant Instruments
  • Misc ACs for specific systems (e.g. TAWS, TCAS)

We Are Often Asked for Help
  • Aircraft Certification Offices have requested
    help in assessing the human factors aspects of
    designs being proposed for certification
  • How to approach the human factors aspects of
    certification programs
  • How to determine the way the designs should be
  • How to determine whether the designs are
  • How to increase standardization across ACOs
  • Some applicants have also requested assistance
  • Help in planning their compliance activities
  • Better standardization across ACOs
  • Better understanding of the role of FAA HF
    specialists, pilots, and systems specialists with
    respect to HF compliance

How to get help on HF issues
  • FAA AVR HF Specialists

Part 25 Steve Boyd Loran Haworth John McConnell
Wichita ACOJeff Holland
Part 21 Colleen Donovan Glen Galloway Bill
Kaliardos (AIR-130)
Part 23 Frank Bick
Atlanta ACO Gina Bolinger
Part 27, 29 Clark Davenport
National Resource SpecialistKathy Abbott (AVR)
Initiatives Underway or Planned
  • Determine if any new rules or advisory material
    are needed
  • Human Factors Harmonization Working Group (HWG)
  • Avionics Systems HWG (now working 25.1322/AC and
    AC 25-11)
  • Flight Guidance Systems HWG (now working
  • Provide improved human factors information to the
  • Human Factors Job Aid - will also be released to
  • A relational database that will allow multiple
    entry paths to
  • Regulations
  • Systems
  • Human Factors Issues
  • Research, policy, and other supporting data

Initiatives Underway or Planned (continued)
  • Develop policies supporting the human factors
    aspects of certification programs
  • Information on Human Factors Certification Plans
    (Policy ANM 99-2, published in October 99)
  • Information on human factors methods of
    compliance (Policy ANM-01-03, draft published in
    May 01)
  • Information on human factors test planning
  • Information on human factors test and evaluation
    acceptance criteria
  • Information on roles and responsibilities for
    human factors compliance issues.
  • Note The policies are being published in the
    Federal Registerso that industry can be fully
    aware of the policies andprovide comments.

Policy on Human Factors Certification Plans (HFCP)
  • There is no regulatory requirement for applicants
    to submit a Human Factors (or any other)
    Certification Plan - this policy DOES NOT require
  • However, the FAA believes that HFCPs can be a
    very beneficial aid to communication
  • The FAA recognizes that not all projects warrant
    an HFCP
  • The policy provides information which can be used
    by the ACO when reviewing an applicants HFCP
  • The policy is not intended to be a strict outline
    for an HFCP
  • As the ACO uses the policy when reviewing an
    HFCP, it may help both the ACO and the applicant
    identify and focus on key compliance issues
    associated with HF

The Main Sections of the HFCP Policy
  • Background information
  • A recommended outline for the HFCP (derived from
    AC 21-40), with explanation of the sections
  • Applicants have been using the outline, with a
    lot of tailoring
  • A partial list of Part 25 regulations related to
    human factors, with discussion of each regulation
  • A list of related documents
  • A hypothetical sample certification plan
  • A quick reference guide (checklist) for reviewing

Generic HFCP Outline
  • 1. Introduction
  • 2. System Description
  • Intended function
  • Flight Deck Layout Drawings
  • Underlying Principles for Automation Logic
  • Underlying Principles for Crew Procedures
  • Assumed Pilot Characteristics
  • 3. Certification requirements
  • 4. Methods of compliance
  • 5. System safety assessments
  • 25.1309 - When pilots are expected to intervene
    to mitigate failures
  • 6. Operational considerations
  • How operational certification issues will be
    integrated into the evaluations (e.g. how will
    proposed MMEL configurations be tested?)
  • 7. Certification documentation

Human Factors Methods of Compliance (MOC) Policy
  • When we developed the policy on HFCPs, we
    provided a small amount of information regarding
    methods of compliance.
  • ACOs needed information about what to consider
    when reviewing proposed MOCs
  • Strengths and weaknesses of each MOC
  • How technology issues impact the effectiveness of
    an MOC
  • MOC issues for some of the more challenging HF
  • This policy can be thought of as a tutorial on
    MOCs for regulations related to human factors

How Design Characteristics affect the MOC
  • Degree of integration/independence Integrated
    products or HF issues need an integrated
  • Novelty/past experience More rigorous methods
    may be called for if the technology is
  • new,
  • used in some new application,
  • new for the particular applicant, or
  • unfamiliar to the certification personnel.
  • Complexity/Level of automation More complex and
    automated systems typically require test methods
    that will reveal how that complexity will
    manifest itself to the pilot, in normal and
    backup or reversionary modes of operation.

How Design Characteristics affect the MOC
  • Criticality Highly critical systems may require
    testing in the most realistic environments (high
    quality simulation or flight test), because any
    problems are more likely to have serious
  • Dynamics If the control and display features of
    the product are highly dynamic, the compliance
    methods should be capable of replicating those
    dynamic conditions.
  • Subjectivity of acceptance criteria As the
    acceptance criteria become more subjective, the
    applicant will need to use more integrated test
    methods, so that the evaluations take into
    account the aspects of the integrated flight deck
    that may affect those evaluations.

Intent of the MOC policy
  • It is intended to
  • Identify design-related and regulation-specific
    issues to consider when the ACO reviews the
    applicants proposed MOCs
  • Direct the ACO to the appropriate Advisory
  • Provide a basis for an MOC discussion between the
    ACOs and applicants
  • It IS NOT intended to
  • Supercede any existing advisory material
  • Specify an acceptable MOC for any regulation
  • Require a new document justifying MOCs
  • The policy is provided to the public (i.e.
    applicants) so that they will know what we will
    consider when reviewing proposed designs
  • If any harmonization working groups (Human
    Factors, Avionics, or Flight Guidance) develop
    new rules and/or advisory material related to
    human factors, the policies will be reviewed and
    revised as necessary.

Human Factors MOC policy
  • The policy can be used regardless of how an
    applicant chooses to document the relevant
    regulations and how compliance will be shown
  • The main sections of the policy
  • Background information
  • A discussion of each method of compliance
  • A discussion of design characteristics that may
    affect the MOC
  • A recommended process for addressing
    regulation-specific MOC issues
  • A partial list of Part 25 regulations related to
    human factors, with discussion of the MOC issues
    for each regulation
  • A list of related documents, including Advisory
  • A hypothetical sample MOC briefing(based on the
    example in the HFCP policy)

Tailoring the MOCs
  • The FAA recognizes that decisions concerning
    MOCs for human factors issues are complex and
  • In most cases, selecting the appropriate MOC for
    a regulation in a specific project will be based
    on an understanding of the human factors issues
    and the capabilities and limitations of the
    various MOCs with regard to the issue and the
    regulation. However, it may be appropriate to
    consider other factors to ensure that the desired
    MOCs are reasonable for the specific project.
  • These other factors include
  • The complexity of the project.
  • The safety implications of the human factors
  • The availability and need for test environments
    (simulators, for example).
  • The experience base of the applicant.
  • The cost and schedule implications of each MOC.

Tailoring the MOC (continued)
  • The Certification Team should strive to agree on
    MOCs that effectively show compliance with the
    regulation in a manner that is commensurate with
  • The significance of the human factors safety
    risks, and
  • The complexity of the issues underlying a finding
    of compliance.

Bilateral Cooperation/Agreements
  • Technical Agreement - Airworthiness Certification
  • Philosophy - Place maximum reliance on the
    system of the certificating authority (state of
    design), who is most knowledgeable of the
  • Validating/importing authority - Define early in
    the project any significant items where they wish
    to retain involvement, otherwise the assumption
    is that all determinations of compliance can be
    conducted by the certificating authority
  • Assumes and requires formal meetings and exchanges