14 CFR § 121.315

Each certificate holder shall provide an approved cockpit check procedure for each type of aircraft.

The approved procedures must include each item necessary for flight crewmembers to check for safety before starting engines, taking off, or landing, and in engine and systems emergencies. The procedures must be designed so that a flight crewmember will not need to rely upon his memory for items to be checked.

The approved procedures must be readily usable in the cockpit of each aircraft and the flight crew shall follow them when operating the aircraft.