Definition
A specific paragraph within Title 14 of the Code of Federal Regulations, Part 23, that establishes one of the conditions used in determining the minimum control speed (VMC) of a multi-engine airplane during certification. Section 23.149(b)(3) specifies that VMC must be determined with the airplane banked not more than 5 degrees toward the operating engine. This bank angle limit is one of several certification conditions designers and test pilots must meet when establishing the published VMC value.
Plain English
It is one of the rules in the federal aviation regulations that says how manufacturers must measure the slowest speed at which a multi-engine airplane can still be controlled with one engine out. This particular rule says the test must be done with the airplane banked no more than 5 degrees toward the working engine.
Context Anchor
Seen in the Airplane Flying Handbook discussion of how the published VMC value is derived during airplane certification.
Derivation
The numbering follows the standard federal regulation format: Title 14 (Aeronautics and Space), Part 23 (airworthiness standards for normal-category airplanes), Section 149 (the section dealing with VMC), paragraph (b), subparagraph (3). Reading regulatory citations becomes second nature once you recognize the pattern: section number, then letter, then number.
Why Pilots Care
It ensures the VMC speed listed in the pilot's operating handbook comes from standardized testing that directly relates to real engine-out handling limits.
Intuition Check
Do not read this as a section of the airplane or a checklist step. It is a legal citation pointing to one exact paragraph in the certification rules.
Example Sentence 1
The handbook explains that the published VMC was established under the conditions of section 23.149(b)(3), which permits up to 5 degrees of bank toward the operating engine.
Example Sentence 2
Understanding section 23.149(b)(3) helps a pilot see why the handbook VMC is measured with a slight bank into the good engine.