At what altitude is the EMER DEPRESS Switch prohibited?

• A. 5,000 ft
• B. 10,000 ft
• C. 15,000 ft
• D. 20,000 ft

Answer: (C)

The EMER DEPRESS switch is a powerful control that rapidly vents cabin pressure. It’s meant to be used only within safe operating limits, because dumping pressure quickly at high altitude can leave occupants fighting hypoxia with little time to put on oxygen and can create hazardous conditions for the crew and airframe.

That’s why it’s prohibited above 15,000 feet. At or below this altitude, the rapid depressurization can be managed safely with immediate oxygen protection and the system can be used in certain emergencies. Above 15,000 feet, the risk to safety and system integrity outweighs the potential benefit, so the switch must not be used.