In choosing between aluminum and copper wires for weight-sensitive aircraft applications, which statement is most accurate?

• A. Copper is always used regardless of weight.
• B. Aluminum's lighter weight makes it favorable when weight matters.
• C. Weight is never a factor in wire selection.
• D. Color of insulation determines the choice.

Answer: (B)

Weight is a critical factor in aircraft wiring, so the material choice often hinges on how much weight can be saved without compromising electrical performance. Aluminum conducts electricity less efficiently than copper, so you usually need a larger cross-section to carry the same current. Despite that, aluminum’s density is much lower than copper’s, so the overall weight for a given current-carrying need can be less. This makes aluminum advantageous in weight-sensitive sections of the aircraft, provided the design accounts for different termination methods, potential corrosion considerations, and insulation/connector compatibility. That balance is what makes aluminum the more accurate statement: its lighter weight makes it favorable when weight matters.

The other options ignore this weight tradeoff. Copper isn’t always used just because weight isn’t a concern, and weight can be a decisive factor in aircraft wire selection. The insulation color does not determine the conductor material.