What action is required before any aircraft flight?

Checking fuel levels and weights is a critical step required before any aircraft flight. This action is essential for ensuring that the aircraft can operate safely, efficiently, and within regulatory limits. Proper fuel management combines assessing the quantity and type of fuel needed for the flight with monitoring the weight of the aircraft, which includes passengers, cargo, and fuel. Overloading an aircraft can lead to performance issues during takeoff, flight, and landing, thus making this check vital for the safety of the flight.

Other actions, while important in their own right, do not universally apply to every flight scenario or may not be as essential as confirming fuel and weight. For instance, conducting a technical briefing with passengers or ensuring all passengers have boarding passes pertains more to passenger management and safety protocols rather than the fundamental aircraft operational requirements. Filing a special flight plan typically involves specific circumstances, not a general prerequisite for every flight. Hence, checking fuel levels and weights stands out as the universally necessary action before any aircraft takes off.