Which altitude has a time of useful consciousness of 12 seconds or less?

Which altitude has a time of useful consciousness of 12 seconds or less?

• A. 45,000 feet
• B. 40,000 feet
• C. 30,000 feet
• D. 50,000 feet

Answer: (A)

The altitude at which time of useful consciousness becomes critically limited is of paramount importance for pilots, particularly when operating at higher altitudes where oxygen availability is insufficient for normal brain function. At 45,000 feet, the time of useful consciousness is generally recognized to be around 12 seconds or less. This means that if a pilot were to lose cabin pressure at this altitude, they would have only a very short window to react effectively before impairments due to hypoxia set in. In contrast, the time of useful consciousness increases at lower altitudes, allowing for more time to respond to a decompression event. For instance, at 40,000 feet, the time of useful consciousness is longer than at 45,000 feet, generally exceeding 30 seconds. Similarly, at 30,000 feet, pilots can expect several minutes of useful consciousness before hypoxic effects become dangerously limiting. At 50,000 feet, pilots would also experience a very limited time of useful consciousness, often comparable or even shorter than 45,000 feet due to the even lower atmospheric pressure. This critical understanding highlights the importance of supplemental oxygen systems and cabin pressurization for aircraft operating at altitudes where these conditions exist.

The altitude at which time of useful consciousness becomes critically limited is of paramount importance for pilots, particularly when operating at higher altitudes where oxygen availability is insufficient for normal brain function. At 45,000 feet, the time of useful consciousness is generally recognized to be around 12 seconds or less. This means that if a pilot were to lose cabin pressure at this altitude, they would have only a very short window to react effectively before impairments due to hypoxia set in.

In contrast, the time of useful consciousness increases at lower altitudes, allowing for more time to respond to a decompression event. For instance, at 40,000 feet, the time of useful consciousness is longer than at 45,000 feet, generally exceeding 30 seconds. Similarly, at 30,000 feet, pilots can expect several minutes of useful consciousness before hypoxic effects become dangerously limiting. At 50,000 feet, pilots would also experience a very limited time of useful consciousness, often comparable or even shorter than 45,000 feet due to the even lower atmospheric pressure.

This critical understanding highlights the importance of supplemental oxygen systems and cabin pressurization for aircraft operating at altitudes where these conditions exist.