An emergency roof hatch:

Question

While emergency roof hatches on buses may be locked in partially-open positions to allow for the movement of fresh air, do not leave them open as a regular practice. It is important to remember that having a hatch open gives the bus a slightly higher clearance.

Accepted Answer

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

Answer

Must always be locked down before traveling.

Answer

Should never be opened, except in an emergency.

Answer

Should always be open while traveling.