Definition
Part 25 of Title 14 of the Code of Federal Regulations, which sets the airworthiness standards for transport category airplanes — generally larger multi-engine aircraft used in airline and commercial operations. It establishes design, performance, and certification requirements, including engine-out takeoff performance and obstacle clearance criteria.
Plain English
A set of FAA rules that say how big commercial-style airplanes must be designed, built, and tested before they are allowed to fly passengers. It includes strict rules about how the airplane must still climb safely if one engine fails on takeoff.
Context Anchor
Seen in performance planning and obstacle clearance discussions for transport category airplanes, especially when checking whether the airplane can safely continue after an engine failure on takeoff.
Derivation
‘Part’ refers to a numbered section of the Federal Aviation Regulations (14 CFR). Part 25 specifically covers transport category airplanes. The numbering is just the regulation’s address — like a chapter number in a rulebook.
Why Pilots Care
Pilots of large multi-engine jets use these standards to confirm their aircraft meets required climb gradients and clearances during engine-out takeoff scenarios.
Intuition Check
Do not read “Part 25” as just a chapter or page number in the handbook. Here it means a specific FAA regulation: 14 CFR Part 25, the certification rule set for transport category airplanes.
Example Sentence 1
The Boeing 737 is certified under Part 25, so its takeoff performance data accounts for continued climb after an engine failure.
Example Sentence 2
Under Part 25 the net flight path must clear obstacles by at least thirty-five feet during an engine failure on takeoff.