What is a key reason to keep maximum zero fuel weight within range?

Keeping the maximum zero fuel weight within range is primarily about ensuring the aircraft's structural integrity. The maximum zero fuel weight is the maximum weight of the airplane without the weight of the usable fuel. If the aircraft exceeds this weight, it can lead to structural issues because the airframe is not designed to handle loads beyond established limits without fuel being taken into consideration.

When the weight is managed correctly, it helps maintain the safety margins built into the aircraft's design. Each aircraft has specific weight limitations set by the manufacturer, and exceeding these can result in excessive stress on the wings, fuselage, and other critical parts of the structure. Therefore, adherence to maximum zero fuel weight limits is essential to prevent potential damage that could compromise the aircraft's safety and performance.

The other choices, while significant in their own right, do not directly address the primary concern of structural integrity related to exceeding maximum zero fuel weight.