When can a handheld device be used while driving a CMV?

Using a handheld device while driving a commercial motor vehicle (CMV) is strictly regulated to enhance safety on the road. The correct option indicates that a handheld device may only be used in emergencies or when legally permitted. This means that while operating a CMV, drivers should avoid any distractions from handheld devices unless faced with a critical situation that requires immediate action, such as calling for help after an accident or a mechanical failure.

In contrast, using a handheld device at any time can lead to distractions that increase the risk of accidents. Stopping at traffic lights does not exempt a driver from the regulations concerning handheld devices, as the vehicle is still considered in operation. Additionally, using a handheld device during long trips to alleviate boredom can detract from the driver's focus and attention to the road, further reinforcing the need for strict limits on when these devices can be used. Therefore, the emphasis is on prioritizing safety and minimizing distractions while driving a CMV.