When flying at high altitudes, what should pilots always be prepared for?

Pilots flying at high altitudes should always be prepared for decompression events. At these altitudes, the lower air pressure can result in significant physiological effects. If there is a loss of cabin pressure, such as in the event of a structural failure or malfunction, it can lead to hypoxia, where the body is deprived of adequate oxygen. This situation can escalate quickly, making it crucial for pilots to recognize and respond to rapid decompression effectively.

In high-altitude operations, aircraft are designed with pressurized cabins to prevent these issues, but pilots must remain vigilant and prepared to implement emergency procedures if decompression occurs. This could involve utilizing supplemental oxygen, descending to a safer altitude, and ensuring the safety of all passengers and crew.

Other aspects like changes in air traffic control frequency, rapid weather shifts, and radiation exposure, while certainly relevant considerations, do not pose the immediate and critical physiological threat that a decompression event does in high-altitude flight scenarios. Thus, being prepared for decompression is paramount for safety in these flights.