An emergency roof hatch:

Question

When operating a bus, you may sometimes open a roof hatch partway to bring fresh air into the vehicle. However, it is not a good idea to make this a regular practice. Opening a hatch will slightly increase your bus's clearance.

Accepted Answer

May be left partially open while traveling to allow for the movement of fresh air.

Answer

Should only be open during an emergency.

Answer

Should always be open.

Answer

Does not need to be locked.