What is the time of useful consciousness at 28,000 feet?

The time of useful consciousness at 28,000 feet is typically around 2 to 3 minutes. This is the duration a person can function effectively without supplementary oxygen after a rapid decompression at that altitude. Above this height, the availability of oxygen becomes significantly lower, and as a result, cognitive functions start to decline rapidly.

At 28,000 feet, the body's ability to receive enough oxygen to maintain brain function deteriorates, and the individual can lose consciousness shortly after this time frame begins. This is critical knowledge for pilots and passengers alike, as it emphasizes the importance of having supplemental oxygen available during flights at high altitudes, as well as the need for quick and effective response procedures in the event of cabin decompression.

Other choices suggest longer periods of useful consciousness, which would be inaccurate based on physiological studies concerning hypoxia at high altitudes.