An amber CKPT ALT annunciator illuminates if cockpit pressure altitude rises above what level?

The amber CKPT ALT annunciator illuminates when the cockpit pressure altitude exceeds 19,000 feet. This is significant because it serves as a warning to the pilots that the cabin altitude is becoming dangerously high, which could lead to hypoxia if the pressure is insufficient. Cabin altitude warnings are crucial for ensuring the safety and health of the crew and passengers, as it prompts timely corrective actions, such as descending to a lower altitude or using supplemental oxygen. Understanding the pressure altitude limits helps pilots remain vigilant and maintain operational safety during flight.