“Whenever the intermittent warning horn sounds in flight, at an airplane flight altitude above 10,000 feet MSL:
• Immediately don oxygen masks and set regulators to 100%
• Establish crew communications
• Do the CABIN ALTITUDE Warning or rapid depressurization non-normal checklist.
Both pilots must verify on the overhead Cabin Altitude panel that the cabin altitude is
stabilized at or below 10,000 feet before removing oxygen masks”
