ASTM F3491-21

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3491 − 21
Standard Practice for
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Enhanced Indication Methods in Aircraft
This standard is issued under the fixed designation F3491; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 This practice provides methods for how Enhanced
mine the applicability of regulatory limitations prior to use.
Indications are provided to the responsible crewmember when
1.6 This international standard was developed in accor-
an applicant uses these indications in support of compliance
dance with internationally recognized principles on standard-
with the requirements for Stall Characteristics, Stall Warning,
ization established in the Decision on Principles for the
and Spins applicable to Normal Category Aeroplanes, using
Development of International Standards, Guides and Recom-
Specification F3180/F3180M.
mendations issued by the World Trade Organization Technical
1.2 The specific types of enhanced indications identified in
Barriers to Trade (TBT) Committee.
Specification F3180/F3180M are as follows:
Type Description 2. Referenced Documents
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2.1 ASTM Standards:
Angle of Attack Angle of attack indication
Angle of Attack Angle of attack indication with trend marker
2.1.1 The following is a list of external standards referenced
Pitch Limit Pitch limit indication displayed on attitude indication
throughout this practice. In all cases, later document revisions
Dynamic Low-Speed Indicated airspeed markings that change with
are acceptable if shown to be equivalent to the listed revision,
Markings flight condition
Airspeed Trend Indicated airspeed trend marker displayed on
or if otherwise formally accepted by the governing CAA;
airspeed indication
earlier revisions are not acceptable.
Flight Path Marker Flight path marker displayed on attitude indication
F3060 Terminology for Aircraft
LOC Alert Alert issued when loss of control likely within trend
window
F3180/F3180M Specification for Low-Speed Flight Charac-
teristics of Aircraft
1.3 An applicant intending to propose this information as
Means of Compliance for a design approval must seek guid- F3117/F3117M Specification for Crew Interface in Aircraft
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ance from their respective oversight authority (for example, 2.2 SAE Standard:
published guidance from applicable civil aviation authority
ARP4102/7 Electronic Displays
(CAA) concerning the acceptable use and application thereof.
3. Terminology
For information on which oversight authorities have accepted
this practice (in whole or in part) as an acceptable Means of
3.1 Definitions—Terminology specific to this practice is
Compliance to their regulatory requirements (hereinafter “the
provided below. For general terminology, refer to Terminology
Rules”), refer to the ASTM Committee F44 web page
F3060.
(www.astm.org/COMMITTEE/F44.htm).
3.2 Definitions of Terms Specific to This Standard:
3.2.1 flight path marker, n—flight path marker shows the
1.4 Units—This document may present information in SI
aircraft’s predicted path based on horizontal and vertical speed,
units, English Engineering units, or both. The values stated in
heading, wind, and possibly other contributing factors.
each system are not necessarily exact equivalents; therefore, to
ensure conformance with the standard, each system shall be
4. Significance and Use
used independently of the other, and values from the two
systems shall not be combined.
4.1 The purpose of this practice is to discuss display or
functional characteristics, or both, of enhanced indications for
1.5 This standard does not purport to address all of the
low-speed awareness.
safety concerns, if any, associated with its use. It is the
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
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This practice is under the jurisdiction of ASTM Committee F44 on General contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Aviation Aircraft and is the direct responsibility of Subcommittee F44.10 on Standards volume information, refer to the standard’s Document Summary page on
General. the ASTM website.
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Current edition approved Aug. 1, 2021. Published September 2021. DOI: Available from SAE International (SAE), 400 Commonwealth Dr.,Warrendale,
10.1520/F3491-21. PA 15096, http://www.sae.org.
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