Definition
A specific paragraph within Title 14 of the Code of Federal Regulations, Part 23, that establishes the certification requirements for minimum control speed (VMC) on multiengine airplanes. It defines VMC as the calibrated airspeed at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the airplane with that engine still inoperative and thereafter maintain straight flight at the same speed with an angle of bank of not more than 5 degrees.
Plain English
A federal rule that tells airplane manufacturers exactly how to determine the lowest speed at which a multiengine airplane can still be controlled after one engine quits. It also sets the conditions the test pilot must meet, including keeping the wings nearly level.
Context Anchor
You will see this term in discussions of how published VMC is determined for multiengine airplanes.
Derivation
Section 23.149(a) is shorthand for Title 14 CFR Part 23, paragraph 149, subparagraph (a). Part 23 covers airworthiness standards for normal-category airplanes. Knowing the citation helps pilots find the original rule rather than relying on summaries.
Why Pilots Care
It guarantees that published VMC values are measured under consistent, realistic conditions so pilots can rely on them for safe engine-out decision-making.
Intuition Check
Do not read “section” as a physical section of the airplane. Here, it means a numbered part of an FAA regulation. Do not read 23.149(a) as a performance speed. It is the rule paragraph that defines the speed.
Example Sentence 1
The published VMC in the POH was determined under the test conditions specified in section 23.149(a), including a bank angle of no more than 5 degrees toward the operating engine.
Example Sentence 2
A pilot reviewing the airplane flight manual can trace the published VMC number back to the requirements in section 23.149(a).