Standard Active Last Updated: Sep 02, 2021 Track Document
ASTM F3491-21

Standard Practice for Enhanced Indication Methods in Aircraft

Standard Practice for Enhanced Indication Methods in Aircraft F3491-21 ASTM|F3491-21|en-US Standard Practice for Enhanced Indication Methods in Aircraft Standard new BOS Vol. 15.09 Committee F44 2021-09-02 00:00:00
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Significance and Use

4.1 The purpose of this practice is to discuss display or functional characteristics, or both, of enhanced indications for low-speed awareness.

4.2 The information in this practice may be used in developing enhanced indications that are part of the compliance approach for Normal Category Aeroplanes using Specification F3180/F3180M, Stall Warning, and Specification F3117/F3117M.


1.1 This practice provides methods for how Enhanced Indications are provided to the responsible crewmember when an applicant uses these indications in support of compliance with the requirements for Stall Characteristics, Stall Warning, and Spins applicable to Normal Category Aeroplanes, using Specification F3180/F3180M.

1.2 The specific types of enhanced indications identified in Specification F3180/F3180M are as follows:





Angle of Attack

Angle of attack indication

Angle of Attack

Angle of attack indication with trend marker

Pitch Limit

Pitch limit indication displayed on attitude indication

Dynamic Low-Speed Markings

Indicated airspeed markings that change with flight condition

Airspeed Trend

Indicated airspeed trend marker displayed on airspeed indication

Flight Path Marker

Flight path marker displayed on attitude indication

LOC Alert

Alert issued when loss of control likely within trend window

1.3 An applicant intending to propose this information as Means of Compliance for a design approval must seek guidance from their respective oversight authority (for example, published guidance from applicable civil aviation authority (CAA) concerning the acceptable use and application thereof. For information on which oversight authorities have accepted this practice (in whole or in part) as an acceptable Means of Compliance to their regulatory requirements (hereinafter “the Rules”), refer to the ASTM Committee F44 web page (

1.4 Units—This document may present information in SI units, English Engineering units, or both. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 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.

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Book of Standards Volume: 15.09
Developed by Subcommittee: F44.10
Pages: 2
DOI: 10.1520/F3491-21
ICS Code: 49.020