Which of the following conditions must be met when solving weight and balance problems in aviation?

When addressing weight and balance problems in aviation, one of the primary conditions that must always be adhered to is that the weight of the aircraft must remain below the maximum gross weight limit established by the manufacturer. This is crucial because exceeding the maximum gross weight can significantly impair the aircraft's performance, increase stall speed, and reduce control effectiveness, which can lead to unsafe flight conditions.

Maintaining the weight within the allowed limits ensures that the aircraft can achieve its intended performance characteristics, including takeoff, climb, cruise, and landing capabilities. Not only does this enhance safety, but it also complies with regulatory requirements that are vital for legal and safe operation.

Other conditions that may seem relevant, such as the aircraft being under 5,000 pounds, balance within pilot experience limits, or fuel being at half capacity, do not universally apply to all aircraft and situations. These conditions are not standard requirements for weight and balance calculations and may vary greatly depending on specific aircraft types, configurations, and operational needs. Maintaining awareness of the maximum gross weight is the fundamental principle that governs safe operation and weight management across all aviation contexts.