SAE ARP6909-2020 PDF

Full title and description

Methods for Determining the Seat Reference Point (SRP) and the Buttock Reference Point (BRP) for Seats in Transport Aircraft, Civil Rotorcraft, and General Aviation Aircraft. This Aerospace Recommended Practice defines acceptable methods to identify and document the SRP and BRP used for passenger and crew seats, establishing a common seat datum and measurement approach for design, test, and certification activities.

Abstract

This ARP provides procedures to determine the Seat Reference Point (SRP) and Buttock Reference Point (BRP), including measurement methods, required documentation, and conventions for reporting the SRP/BRP for fixed and adjustable seats used in transport aircraft, civil rotorcraft, and general aviation aircraft. The practice supports consistent seat geometry definition for ergonomics, restraint system integration, clearance analyses, and certification artifacts.

General information

• Status: Superseded (original ARP6909 issued 2020; updated by ARP6909A in 2025).
• Publication date: 2 November 2020 (issued).
• Publisher: SAE International (Society of Automotive Engineers).
• ICS / categories: 49.140 (space systems and operations) — classification recorded in standards catalogs.
• Edition / version: ARP6909 (2020 edition).
• Number of pages: 17 pages.

Scope

This Aerospace Recommended Practice defines acceptable methods for determining the seat reference point (SRP) and the buttock reference point (BRP), and the documentation requirements for that determination, for passenger and crew seats in transport aircraft, civil rotorcraft, and general aviation aircraft. It applies to fixed and adjustable seats and describes what to record and report so that seat location and geometry are clear and repeatable across design, test, and certification processes.

Key topics and requirements

• Definition and purpose of the Seat Reference Point (SRP) and the Buttock Reference Point (BRP).
• Permitted methods and measurement techniques to determine SRP and BRP on seat assemblies (including reference datums and measurement tools).
• Documentation and reporting requirements for declared SRP/BRP (format, required metadata, seat configuration description).
• Coordinate system conventions and datum establishment for seat location relative to aircraft structure.
• Considerations for adjustable seats and how to report SRP/BRP for different adjustment ranges and positions.
• Anthropometric and ergonomic considerations affecting buttock point determination and repeatability.
• Application notes for passenger and crew seats across transport, rotorcraft, and general aviation categories.

Typical use and users

Used by aircraft seat designers, seat manufacturers, airframe OEMs, certification and compliance engineers, human factors specialists, test laboratories, and regulatory bodies to establish a consistent seat datum for design integration, occupant protection studies, clearance and reach analyses, and certification submissions.

Related standards

Directly related to the updated ARP6909A (the 2025 revision). It is commonly referenced alongside aircraft certification requirements and guidance such as 14 CFR (FAA) and EASA Certification Specifications for seats and occupant protection, and other SAE/industry standards addressing seat strength, crashworthiness, and anthropometric test devices.

Keywords

Seat Reference Point, SRP, Buttock Reference Point, BRP, aircraft seats, seat datum, seat geometry, anthropometry, seat documentation, SAE ARP6909, seat measurement methods.

FAQ

Q: What is this standard?

A: An Aerospace Recommended Practice from SAE that specifies methods to determine and document the Seat Reference Point (SRP) and Buttock Reference Point (BRP) for aircraft seats used in transport aircraft, civil rotorcraft, and general aviation.

Q: What does it cover?

A: Measurement procedures, datum and coordinate conventions, what to record when declaring an SRP/BRP, guidance for adjustable seats and reporting for multiple configurations, and considerations to ensure repeatable, unambiguous seat location information for design, testing, and certification.

Q: Who typically uses it?

A: Seat manufacturers, airframe OEMs, certification engineers, test labs, human factors engineers, and regulators involved in seat design, installation, testing, and certification.

Q: Is it current or superseded?

A: The original ARP6909 was issued on 2 November 2020. It has been updated and superseded by ARP6909A (stabilized/published 1 May 2025). For new projects or certification artifacts, reference the ARP6909A edition unless a contract or authority requires the 2020 text.

Q: Is it part of a series?

A: It is part of SAE’s suite of Aerospace Recommended Practices and standards addressing seats, occupant protection, and anthropometrics; the direct successor is ARP6909A (2025 revision).

Q: What are the key keywords?

A: SRP, BRP, seat reference point, buttock reference point, seat datum, aircraft seats, anthropometry, seat documentation, SAE ARP6909.