Definition
A regulation in Title 14 of the Code of Federal Regulations, Part 23, that establishes minimum control speed requirements (VMC) for multiengine airplanes certificated under that part. It defines the conditions under which VMC is determined and the directional control standards the airplane must meet with one engine inoperative.
Plain English
It is the FAA rule that sets out how the minimum control speed for a multiengine airplane is determined, and what the airplane has to be able to do when one engine quits.
Context Anchor
You will see this reference in multiengine training when the handbook explains where the official meaning of VMC comes from.
Derivation
Section comes from a word meaning a cut or division. In regulations, a section is one numbered division of a larger set of rules. Here, 23.149 means section 149 within Part 23 of the federal aircraft certification rules.
Why Pilots Care
It establishes the published Vmc value that appears in every multiengine aircraft's POH and directly affects safe takeoff and climb decisions after an engine failure.
Intuition Check
Do not read section 23.149 as a page or paragraph in the Airplane Flying Handbook. Here it means a specific federal regulation: 14 CFR § 23.149.
Example Sentence 1
The VMC value published in the POH was established under the specific conditions defined in section 23.149.
Example Sentence 2
Before the checkride the student reviewed section 23.149 to understand how the manufacturer determined the airplane's Vmc.