Definition
A federal regulation, formally titled 'Flight Crewmember Duties,' that prohibits flight crewmembers from performing any non-essential duties or activities during a critical phase of flight. Critical phases of flight include all ground operations involving taxi, takeoff, landing, and all other flight operations conducted below 10,000 feet, except cruise flight. The rule applies to operations conducted under Part 135, which governs commuter and on-demand operations such as charter flights, air taxis, and small commercial carriers.
Plain English
A rule that says pilots flying for charter or commuter operators must focus only on flying the aircraft during the most demanding parts of a flight — taxi, takeoff, landing, and anything below 10,000 feet that isn't steady cruise. No chatting, paperwork, or other distractions during those times.
Context Anchor
Seen in discussions of CFIT prevention, crew discipline, approach briefings, and commercial operations conducted under Part 135.
Derivation
CFR' stands for Code of Federal Regulations — the organized collection of rules issued by U.S. federal agencies. Title 14 covers aeronautics and space. Part 135 covers commuter and on-demand operations. The number after the dash (135.100) identifies the specific section within that part. This is essentially the rule's home address in the regulation library.
Why Pilots Care
Following this rule reduces the chance of losing situational awareness during high-workload phases, directly lowering CFIT risk in Part 135 operations.
Grounding Statement
During a busy descent or approach, this rule keeps the cockpit focused on only what helps the flight stay safe.
Intuition Check
Do not read this as just a paperwork citation. In this context, it points to a real operating rule: keep nonessential duties and conversation out of critical phases of flight.
Example Sentence 1
Under 14 CFR Part 135.100, the first officer asked the captain to hold non-essential conversation until they climbed through 10,000 feet.
Example Sentence 2
Company training materials emphasize 14 CFR Part 135 — 135.100 to prevent distractions that have led to past CFIT events.