What is required of pilots before each takeoff when carrying passengers?

The requirement for an oral briefing for all passengers before takeoff is focused on ensuring that passengers are informed about essential safety procedures, emergency protocols, and any specific instructions relevant to the flight. This briefing allows pilots to communicate critical safety information, such as the use of seat belts, location of exits, and procedures for emergency situations, ensuring that passengers are prepared and can respond effectively if necessary.

While preflight checks are certainly crucial, they are standard practice for all flights, not specifically tied to carrying passengers. Flight plan submission is also important for the flight's legality and air traffic control but does not directly relate to passenger safety briefings. Lastly, completion of a flight review pertains to pilot proficiency and certification rather than addressing the immediate needs of the passengers on board. Thus, the oral briefing stands out as a specific requirement when carrying passengers, emphasizing their safety and preparedness.