Significance and Use
5.1 The terminology within this guide references ASTM Terminology E3188. These terms should be thoroughly familiarized before a review of this guide is accomplished.
5.2 U.S. and international guidance advocate that transport aircraft perform a time-of-arrival landing assessment for all runway conditions to include dry, wet, and contaminated surfaces. The function of this assessment is to provide an operator with a standardized means for anticipating the level of braking action upon landing. An aircraft braking action report is then created based on the actual level of braking achieved. This information can then be communicated for analysis.
5.3 The use of aircraft data to generate an aircraft braking action report is intended to mitigate human errors due to issues of training, experience, or cognitive bias that may occur with pilot braking action reports. For aircraft that use FAA AC 25-32 or equivalent (ICAO Doc 10064 and AMC 25.1592, for example) to assess landing performance, aircraft braking action reports can be considered applicable to a wide range of aircraft types and manufacturers.
5.4 The ABAR produced by such a system may not result in an observation representative of the entire prepared surface intended to be used for landing, deceleration, or both.
5.5 It is the responsibility of the aircraft and airport operator to create policies and procedures regarding the use of an ABAR. It is important to fully understand the capabilities and any limitations that may exist with such a system. It is the responsibility of the aircraft operator to ensure that proper training and system knowledge are in place prior to the use of these systems.
5.6 FAA and ICAO guidance use the term Aircraft Wheel Brake Coefficient or MU Brakes (see Terminology E3188) to define the reference distances to be used by the flight crew in accomplishing a time-of-arrival landing assessment. MU Brakes is also commonly used in research programs and accident investigations. While the use of this term is a standard industry practice, other means of quantifying aircraft wheel braking performance may be employed.
5.7 Aircraft of different manufacturers and type designs may use a variety of data sources. Therefore, this process of quantification cannot be universally detailed for all aircraft. This standard describes requirements for specific data, as well as categories of data that may be measured or inferred so that an appropriate calculation method may be employed.
5.8 This standard may be used to support the design and operation of a variety of intended functions. The specific description of each function will determine the compliance methods that should be followed.
Note 1: Intended functions may include the simple transmission of data, flight crew alerting, the discrimination of a simple boundary between two braking levels, or a multitude of braking levels.
5.9 There is a wide range of methods that may be used to show compliance. The party responsible for assessing an applicant’s compliance should use this standard as a guide; however, the specific methods deemed acceptable may be determined based on the specifics of the design.
5.10 This standard is intended to be applicable to any aircraft with an anti-skid system and available flight data. A nominal rate of data acquisition of 4 Hz represents requirements for flight data recorders. Data sample requirements are intended to allow older model aircraft and anti-skid systems enough information to demonstrate stable performance characteristics.
5.11 ABAR systems are intended to reflect a portion of the landing area that can reasonably be considered relevant for operational decision-making. It is incumbent on the end user to incorporate policies and procedures to appropriately utilize this information in a safety management process.
5.12 Mapping Accuracy—Compliance with this standard is intended to provide an ABAR produced by a system in which there is reasonable confidence that the reported braking action will be within ± one level of wheel braking, when using the six (6) categories of braking action reports as documented in FAA AC 25-32 or 10.2.2. For systems using fewer than six (6) levels of braking action, the standard for data precision will remain the same and the accuracy therefore increased.
Note 2: Dry runway conditions are not described using braking action.
5.13 Deviations from this standard may be considered acceptable if they are appropriately documented and justified.
5.14 The list of parameters included in Annex A1 is categorized to maximize the ability of the designer to adhere to the philosophies documented herein. The list in this standard should be considered a minimum list of parameters normally available from an aircraft’s data system. These parameters are then used in modeling aerodynamics, propulsion, and other forces. A method of direct measurement or alternate means of determining wheel braking characteristics may result in a deviation from this list.
Scope
1.1 This guide applies to any automated system that uses data from an aircraft to create an Aircraft Braking Action Report (ABAR) (see Terminology E3188). The system may be installed on an aircraft or operated remotely. This standard is intended to ensure that all ABARs created by automated systems meet a minimum level of quality and represent a standardized set of assumptions. This standard does not provide any guidance or means for the dissemination of an ABAR or related information.
1.1.1 Aircraft systems producing ABARs or ABAR-related flight crew alerts are covered by the appropriate regulatory guidance for aircraft certification.
1.2 This standard utilizes the terms and methods relating to aircraft anti-skid systems as documented in FAA AC 25-32.
1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 Risk Management—Aircraft braking action reports contain information that may be used to reference the operating limits of an aircraft. Section 6 details the safety analysis and specific guidelines for airborne and remotely operated systems.
1.5 Operational Use—This standard does not address operational considerations nor recommend policies regarding the use of an aircraft braking action report.
1.6 Mandating and Recommended Phrases—To enhance comprehension and clarity, required and recommended tasks are listed with the following nomenclature:
1.6.1 The term “shall” is used to indicate a provision is mandatory. Such requirements are sequentially listed as “REQXX.”
1.6.2 The term “should” is used to indicate that a provision is recommended as a good practice. Such recommendations are sequentially listed as “RECXX.”
1.7 This standard provides guidance for performing one or more specific functions. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this standard may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project’s many unique aspects. The word “Standard” in the title means only that the document has been approved through the ASTM consensus process.
1.8 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.
1.9 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.
