Which of the following can help in the detection of a concealed fire in aircraft?

Thermal imagers are highly effective tools for detecting concealed fires in aircraft due to their ability to visualize heat patterns. These devices can identify temperature differences that may indicate the presence of a fire hidden from plain sight, such as within walls or in cargo holds. Thermal imaging can reveal hot spots and areas of excessive heat, allowing firefighters to focus their efforts more effectively and address potential hazards before they escalate.

In contrast, visual monitoring relies primarily on the observer's ability to see flames or smoke, which may not be present in the early stages of a concealed fire. While visual inspections can supplement fire detection efforts, they are less reliable for identifying fires that are not immediately visible.

Handheld fire extinguishers serve as a method for fire suppression rather than detection. Although they are crucial for responding to a fire once it is identified, they do not assist in locating a concealed fire.

Manual checks may include physical inspections or system tests, but these can be time-consuming and may miss hidden fires unless specific procedures and equipment are used. Overall, thermal imagers provide a technological advantage in detecting concealed fires, making them the optimal choice in this scenario.