Definition
A regulation (14 CFR 121.542 and 135.100) that prohibits flight crew members from performing any non-essential duties or activities during critical phases of flight. Critical phases include all ground operations involving taxi, takeoff, and landing, and all other flight operations conducted below 10,000 feet, except cruise flight. Non-essential activities include eating meals, engaging in non-essential conversation, and reading publications not related to the proper conduct of the flight.
Plain English
A rule that says pilots must focus only on flying the aircraft during the busiest, most safety-critical parts of a flight — taxiing, taking off, landing, and any flying below 10,000 feet. No chit-chat, no meals, no distractions.
Context Anchor
You will see this term in runway incursion prevention, taxi procedures, crew coordination, and discussions about avoiding distractions during high-workload parts of flight.
Derivation
The word 'sterile' comes from the Latin sterilis, meaning 'barren' or 'free from contamination.' Here it's used in the sense of keeping the cockpit 'free from' anything that doesn't belong there during critical phases — namely, distractions and non-essential talk.
Why Pilots Care
It helps prevent distractions that could lead to runway incursions or other safety incidents during busy flight phases.
Intuition Check
Sterile does not mean the cockpit has been disinfected. Here it means the cockpit is kept free of nonessential talk and activity so the crew can focus on safety.
Example Sentence 1
As they taxied toward the runway, the captain reminded the first officer that they were under the sterile cockpit rule and ended the casual conversation.
Example Sentence 2
Below 10,000 feet, the sterile cockpit rule prohibits discussing anything not related to the flight.