What is typically tested during operational carbon monoxide detection tests?

The correct answer focuses on the safety of heating and exhaust systems, which are critical areas where carbon monoxide (CO) can be generated. During operational carbon monoxide detection tests, the primary goal is to ensure that any potential sources of CO—such as heaters or engine exhausts—are functioning properly and do not leak harmful gases into the cabin environment.

Testing these systems is crucial because carbon monoxide is a colorless, odorless gas that can cause serious health issues, including headaches, dizziness, and even fatal poisoning. Ensuring that heating and exhaust systems are safe helps maintain a healthy cabin atmosphere for passengers and crew.

The other options, while related to aircraft operations, do not directly address the primary concern of detecting CO. Fuel efficiency pertains to engine performance rather than safety checks. The performance of cabin pressure systems is focused on maintaining adequate pressure rather than monitoring CO levels. Oxygen supply reliability is concerned with ensuring there is enough oxygen for passengers, which is a separate issue from carbon monoxide risks associated with heating and exhaust systems.