When does cabin pressure exceed ambient air pressure during flight?

Cabin pressure exceeding ambient air pressure typically occurs in the context of aircraft operation where the cabin's environment is managed to ensure passenger comfort and safety. When the cargo hold is sealed, it can create a situation where there is a difference in pressure. However, this alone does not fully capture the situation in practical aviation terms.

During high-altitude flight, the external atmospheric pressure is significantly lower than the pressure maintained inside the aircraft cabin. To provide safe and comfortable conditions for passengers and crew, aircraft are designed to pressurize the cabin. This pressurization system ensures that even at high altitudes, where the ambient air pressure drops, the cabin pressure is maintained at a level that exceeds the outside pressure.

The other options do not represent conditions under which cabin pressure would exceed ambient pressure consistently during standard flight operations. For example, excessive heat buildup may affect temperature control but does not directly correlate with pressure change in a way that would lead to excess cabin pressure in relation to ambient air pressure. Similarly, turning off air conditioning packs impacts the cabin environment but would not increase cabin pressure beyond ambient pressure.

Thus, high-altitude flight is the scenario where cabin pressure is effectively maintained above the ambient air pressure, ensuring safety and comfort for those aboard.