In case of a cabin pressure failure, what immediate action should be taken?

In the event of a cabin pressure failure, the immediate action to take is to activate emergency oxygen masks. This is critical because a sudden loss of cabin pressure can lead to hypoxia, a condition in which the body is deprived of adequate oxygen. The deployment of emergency oxygen masks provides supplemental oxygen to the passengers and crew, allowing them to breathe and maintaining consciousness until an altitude can be attained where supplemental oxygen is no longer necessary or until the situation can be resolved.

While descending to a lower altitude is often a necessary follow-up action to ensure a safe environment, it is essential to first provide immediate oxygen to prevent the dangerous effects of low cabin pressure. Landing at the nearest airport may also be a viable option, but it is not the first priority - ensuring that everyone can breathe is crucial. Increasing speed to regain control is not relevant in this context, as cabin pressure failure primarily concerns oxygen levels rather than aircraft control dynamics. Thus, the activation of emergency oxygen masks is the appropriate initial response in such a critical situation.