About AAR Circular Letters
Circular letter summaries are produced monthly by Greenbrier Management Services Group.
AAR circular letters provide information of general applicability to the railroad industry, including proposed and final rules, revisions, standards and recommended practices, and calls for comments. These summaries provide the main points of circular letters issued in the prior month, as well as important implementation deadlines.
For access to the complete circular letter, please go to my.aar.org/circulars. Circular letters are a fee-based service provided by the AAR’s Transportation Technology Center Incorporated (TTCI). You may subscribe online at publications@aar.com or call 719.584.0538.
Implementation Circulars
C-14699
Subject: Car Repair Billing Data Exchange Schedule Effective January 1, 2026
Summary: The Car Repair Billing Data Exchange (CRBDX), maintained by Railinc, is a monthly exchange of repair bills for foreign freight equipment. The AAR Car Repair Billing committee has implemented a proposal to modify the CRBDX Run Dates for 2025 and onward, with specific schedules for inbound, production, and outbound dates for repair bills.
Date: 12-09-2025
Effective Date: 01-01-2026
C-14703
Subject: Additions to MSRP F, Sensors, S-6102 Wayside Passing Data Format – HBD Detector Readings—Extension of Readings
Summary: This implementation circular advises the industry of modifications to the AAR’s Manual of Standards & Recommended Practices (MSRP) Section F – Sensors / S-6102 Wayside Passing Data Format. The additions include new elements to facilitate hot bearing detector (HBD) alerts in Railinc’s Equipment Health Management System, initially listed as optional but may become mandatory in the future.
Date: 12-17-2025
Effective Date: 12-17-2025
C-14705
Subject: AAR Manual of Standards and Recommended Practices (MSRP) Section K-V Electronics Environmental Requirements and Systems Management, Standard S-9452B.V1.0
Summary: S-9452B.V1.0 lists a set of common data dictionary variables and events for the OPA, allowing railroads and vendors to implement additional variables and events for their own systems management purposes. The standard was adopted in 2023, last revised in 2025, and is attached to the circular in PDF format for incorporation into the MSRP Section K-V Electronics Environmental Requirements and Systems Management.
Date: 12-17-2025
Effective Date: 12-17-2025
C-14706
Subject: AAR Manual of Standards and Recommended Practices (MSRP) Section K-V Electronics Environmental Requirements and Systems Management, Standard S-9420.V1.1
Summary: S-9420.V1.1 provides an industry approved specification for Key Management Services (KMS), which is an industry defined set of services that may be realized by one or more components. S-9420.V1.1 was adopted in 2024 and last revised in 2025 and is attached to the circular in PDF format. It will be incorporated into the next issue of the MSRP Section K-V Electronics Environmental Requirements and Systems Management. In the interim, subscribers should insert the circular in their copy of the MSRP Section K-V and be governed accordingly.
Date: 12-17-2025
Effective Date: 12-17-2025
C-14707
Subject: AAR Manual of Standards and Recommended Practices (MSRP) Section K-V Electronics Environmental Requirements and Systems Management, Standard S-9418.V1.1
Summary: S-9418.V1.1 describes the security aspects of PSA-2 as they relate to the Systems Management Gateway. It was adopted in 2024 and last revised in 2025, and is attached to the circular in PDF format for incorporation into the next issue of the MSRP Section K-V Electronics Environmental Requirements and Systems Management.
Date: 12-17-2025
Effective Date: 12-17-2025
C-14715
Subject: Section C CAR CONSTRUCTION FUNDAMENTALS AND DETAILS, new Specifications M-802 Manufacturer of Freight Cars, Facility Approval and M-803 Manufacturer of Major Subassemblies, Facility Approval, and Discontinuation of S-234
Summary: This circular letter notifies the industry of revisions to Section C CAR CONSTRUCTION FUNDAMENTALS AND DETAILS including the implementation of new Specifications M-802 and M-803 for Manufacturer of Freight Cars and Major Subassemblies, Facility Approval, and the discontinuation of Standard S-2034 Car Builder Certification. The changes include updates to application requirements, technical audit checklists, and activity codes, with the new specifications now implemented and effective immediately.
Date: 12-29-2025
Effective Date: 12-29-2025
Call for Comment
C-14699
Subject: Solicitation of Comments: Revisions to MSRP F, Sensors, S-920, AAR Component Identification (CID) Bar Code Standard – Appendix A (Wheelsets)
Summary: The Equipment Health Monitoring Committee (EHMC) together with the Component Tracking Taskforce (CTTF) is releasing this circular to solicit comments on the proposed modification to the subject section within AAR’s Manual of Standards & Recommended Practices (MSRP), Section F – Sensors. The proposed additions to this standard are specific to Appendix A (Wheelset Data Glossary) Element C307 Axle AAR Condition Code, including a new code, condition code 4, for registering downsized axles as “new.”
Date: 12-16-2025
Comment Period: 30 Days
C-14704
Subject: DRAFT S-9373.V1.0 WSRS Requirements, in support of AAR’s MSRP – Section K-IV Office Architecture and Railroad Electronics Messaging
Summary: The Positive Train Control Interoperability Committee (PTCIC) of the Association of American Railroads (AAR) is publishing DRAFT S-9373.V1.0 WSRS Requirements for review and comment. This document describes how Wayside Status Messages should be exchanged between different railroad’s WSRS applications and other ITCM components, including the format of subscription packages and handling of messages by the WSRS application.
Date: 12-17-2025
Comment Period: 10-day
C-14710
Subject: Solicitation of Comments – Clarification of “Speed is detected” Requirement and Revision to MSRP, Section M – LOCOMOTIVES AND LOCOMOTIVE INTERCHANGE EQUIPMENT: Standard, S-5513 – LOCOMOTIVE ALERTER REQUIREMENTS
Summary: This circular solicits comments for a revision to MSRP Section M, Standard, S-5513 – LOCOMOTIVE ALERTER REQUIREMENTS to clarify the “speed is detected” requirement within the 5.0 ALERTER ACTIVATION AND NULLIFICATION paragraph. The proposed revision harmonizes S-5513 with Transport Canada’s Railway Locomotive Inspection and Safety Rules for Safety Control Systems roll-away protection requirements as they apply to controlling locomotives.
Date: 12-18-2025
Comment Period: 30 Days
C-14713
Subject: DRAFT M-9030.V1.0 Locomotive Consist Control Consist of Operations, in support of AAR’s MSRP – Section K-I Railway Electronics Systems Architecture and Concepts of Operations
Summary: The Railway Electronics Standards Committee (RESC) of the Association of American Railroads (AAR) is publishing DRAFT M-9030.V1.0 Locomotive Consist Control Consist of Operations for review and comments. This document describes the LCC Stack Concept of Operations, enabling messaging between locomotives in consist, covering functionality at all layers of the OSI model except communication between locomotive consists within a train.
Date: 12-19-2025
Comment Period: 45 Days
C-14714
Subject: Solicitation of Comments: Revisions to MSRP F, Sensors, S-6102, Wayside Passing Data Format | Acoustic Bearing Detector (ABD) Readings
Summary: The Equipment Health Monitoring Committee (EHMC) is soliciting comments on proposed additions to the MSRP Section F – Sensors, specifically related to acoustic bearing detector (ABD) data for the Equipment Health Management System (EHMS). The circular details new sections and editorial revisions to the standard, including schema and business rules for ABD data, and invites written comments within thirty days of issuance.
Date: 12-19-2025
Comment Period: 30 Days
CPC-1438
Subject: Solicitation of Comments on Proposed Revisions to MSRP Section C Part III, M-1002, Specifications for Tank Cars, Appendix B, Table B.2
Summary: The Tank Car Committee has accepted the proposed revisions to Appendix B, Table B.2, activity code C6r, allowing certification in the category of one service equipment and granting approval to all other categories for this activity code. The proposed revision removes the reference of 3.1.4 from Table B.2, Activity Code C6r, and requires the attached Exhibit PC-1 (ver. 6.0) form to be filled out and submitted within 30 calendar days from the date of this circular.
Date: 12-17-2025
Comment Period: 30 Days
Notice of Circulars
C-14699
Subject: 2026 AAR M-1003 Quality Assurance Auditor Training Class Schedule Announced
Summary: The Association of American Railroads (AAR) Quality Assurance Committee (QAC) announces the schedule for the 2026 AAR M-1003 Quality Assurance Training classes. The announcement includes class registration links, hotel reservation information, and details about the Basic and Advanced Auditor Training Classes, including dates, locations, and course descriptions.
Date: 12-03-2025
Effective Date: 12-03-2025
C-14696
Subject: 2026 Quality Assurance Conference Update: Topics and Presenters Identified
Summary: The AAR Quality Assurance Committee (QAC) announces the topics and presenters for the Quality Assurance Industry Conference scheduled for February 17-19, 2026, in St. Petersburg, Florida. The conference is a key industry event focused on improving audit consistency, auditing practices, and knowledge of the M-1003 standard, with sessions addressing recent changes and attended by over 300 railroad professionals.
Date: 12-03-2025
Effective Date: 12-03-2025
C-14697
Subject: Informational Circular, Revisions to Field and Office Manuals, Rule 96, Tank Cars
Summary: At the October 2025 meeting of the Arbitration and Rules Committee, a proposal advanced by the Equipment Engineering Committee and the Tank Car Committee was reviewed and approved. The circular details revisions to Field Manual Rule 96.A.2-4 and Rule 96.A.10 regarding tank car conditions and damage.
Date: 12-03-2025
Effective Date: 01-01-2026
C-14698
Subject: Informational Circular, Revisions to Field Manual Rule 36, Figure 36.2, Vented Backing Ring
Summary: In December 2025 the Arbitration and Rules Committee reviewed and approved a proposal to add two new images to Field Manual Rule 36 Figure 36.2. The circular provides the current and proposed text for the inspection of backing rings, including criteria for loose backing rings and vented backing rings missing plugs.
Date: 12-04-2025
Effective Date: 01-01-2026
C-14700
Subject: Informational Circular, Office Manual Rule 107, 2025 Cost Factor
Summary: The AAR Car Repair Billing Committee has approved the 2025 Cost Factor of 309 to be used in 2026, representing a 3.69% increase from 2024. This calculation is based on the UMLER Original Cost Index from October 1, 2024, to September 30, 2025, and the new Cost Factor will be published in Rule 107 of the January 2025 Office Manual, effective January 1, 2026.
Date: 12-10-2025
Effective Date: 01-01-2026
C-14701
Subject: Informational Circular, Car Repair Facility Labor Rate – Effective January 1, 2026
Summary: The Car Repair Facility Labor Rate effective January 1, 2026 is $174.09, a decrease of $1.82 (or 1.06%) from the labor rate estimated on October 1, 2025. Changes this quarter include updated health & welfare rates, payroll taxes, a new Overhead Study, and a new composition of Shortline and Running Repair Agent (RRA) participants.
Date: 12-10-2025
Effective Date: 01-01-2026
C-14708
Subject: 2026 Field and Office Manuals of the AAR Interchange Rules – Preorder Available Now
Summary: The 2026 editions of the Field and Office Manuals of the AAR Interchange Rules are scheduled to be available beginning January 2, 2026, and can now be preordered online. Both manuals are available in paper or electronic format, with electronic versions including security features and periodic updates at no additional cost.
Date: 12-17-2025
Effective Date: 12-17-2025
C-14709
Subject: Informational Circular, Revisions to CRB Procedures Manual, Multiple Revisions
Summary: The CRB Procedures Manual will receive multiple updates effective January 1, 2026. The circular includes a summary of major incoming updates related to various AAR Circular Letters and revisions to the CRB Procedures Manual, including new error codes and billing/invoicing party requirements.
Date: 12-17-2025
Effective Date: 01-01-2026
C-14711
Subject: Informational Circular, Canadian Car Repair Facility Labor Rate – Effective January 1, 2026
Summary: The Canadian Car Repair Billing Labor Rate calculation for January 1, 2026 is $267.61 CAD, an increase from the previous calculation on October 1. Changes include updated health & welfare rates, payroll taxes, a new overhead study, currency conversion factors, and updated pension and employment insurance rates for Canada and Quebec.
Date: 12-18-2025
Effective Date: 01-01-2026
C-14712
Subject: 2026 Quality Assurance Conference Update: Workshops and Registration
Summary: The AAR Quality Assurance Committee (QAC) announces identified workshops for the Quality Assurance Industry Conference scheduled for February 17-19, 2026, in St. Petersburg, Florida. The conference program includes two educational workshops on the final day and an early registration and networking event on February 16th, with over 300 railroad professionals expected to attend.
Date: 12-18-2025
Effective Date: 12-18-2025
CPC-1436
Subject: Manway Design Submission Request for MSRP Section C Part III, M-1002, Specifications for Tank Cars, Appendix D Table D.8- D.13
Summary: According to Appendix E, paragraph 3.3.7, design information and appropriate drawings for manway designs not shown in the manway style charts in Appendix D, Tables D.8 through D.13, are to be submitted to AAR for inclusion in MSRP section C-III, M-1002. The Tank Car Committee requests companies to submit their manway designs for review and approval by March 1st, 2026.
Date: 12-04-2025
Effective Date: 12-04-2025
MARS 2026 Winter Meeting
Lorie Tekorius
President & CEO, The Greenbrier Companies
Featured Speaker at MARS Winter Meeting
January 13–15, 2026 | Schaumburg, IL
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- Railcar Repair Management (Design Review, Drawings, Engineering and AAR Approval Administration)
- Tank Car Reliability & Maintenance Programs (per 49 CFR Subpart F of Part 180)
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