How does the outflow valve function during landing?

The outflow valve serves a crucial role in managing cabin pressure, particularly during landing phases of flight. When an aircraft descends and approaches landing, it is essential to depressurize the cabin to equalize the internal cabin pressure with the atmospheric pressure outside. This process happens gradually to ensure a smooth transition and to maintain passenger comfort.

When the outflow valve moves to the fully open position during landing, it allows the cabin air to escape, effectively reducing the pressure inside the cabin. This action is necessary because as the aircraft descends, the outside air pressure increases, and by opening the outflow valve, the aircraft can achieve proper cabin pressure levels that match the external environment. This function helps prevent discomfort or potential injury to passengers and crew caused by rapid changes in pressure.

In contrast, the other options either imply functions that are not relevant during landing or do not accurately describe the operational behavior of the outflow valve. For instance, increasing cabin pressure or remaining closed would lead to unsafe conditions, while automatic adjustments based on outside temperature do not directly relate to the specific requirements of the landing phase. Thus, the valve opening fully to depressurize the cabin is indeed the correct and optimal operation during this critical time.