On January 19, 1981, the Federal Aviation Administration enacted what pilots simply call the “sterile cockpit rule.” Codified in 14 CFR §§ 121.542 and 135.100, the regulation prohibits flight crewmembers from performing non‑essential duties or engaging in non‑essential activities during critical phases of flight. The rule defines those critical phases as all ground operations involving taxi, takeoff, and landing, and all flight operations below 10,000 feet mean sea level except cruise flight. Eating meals, non‑essential conversation, reading unrelated material, and non‑safety‑related company communications are all forbidden.