What activates the cabin altitude warning system?

The cabin altitude warning system is designed to alert the flight crew when the cabin pressure reaches a certain threshold that may pose a risk to the safety of passengers and crew. This system is activated when the cabin altitude exceeds a predetermined limit, which is typically set to ensure safe operations and passenger comfort. The threshold is established based on regulations and consideration for the physiological effects of altitude on humans.

Exceeding this limit can indicate a failure in pressurization systems or other critical systems within the aircraft, prompting the warning to ensure timely intervention. It is crucial for the safety of all onboard that pilots are alerted to these conditions so they can take appropriate action to maintain cabin pressure.

The other options, while addressing various operational concerns, do not relate directly to the specific functioning of the cabin altitude warning system. For instance, engine overload and excessive turbulence might affect aircraft performance and control but do not specifically trigger cabin altitude warnings. Similarly, low cabin temperature concerns passenger comfort but is unrelated to cabin altitude measurements.