Which of the following would not be an assigned flight level?

The concept of assigned flight levels pertains to the organized system that air traffic controllers use to manage air traffic in controlled airspace. Flight levels are expressed in hundreds of feet above sea level and are typically referenced with "FL" followed by the altitude in hundreds of feet.

In this context, FL160, FL180, and FL220 all represent standard altitudes that are commonly assigned to aircraft during operations. FL160 means 16,000 feet, FL180 is 18,000 feet (the standard transition altitude in the United States), and FL220 is 22,000 feet. These flight levels are actively used for air traffic separation and route planning, making them suitable for assignment by air traffic control.

On the other hand, FL500 represents a flight level significantly above typical operational altitudes. While theoretically possible, altitudes as high as FL500 are generally not used for commercial or general aviation flights. This is primarily due to the limits of aircraft performance and the airspace structure. Most commercial jets operate well below this level. Therefore, FL500 is not a standard, assigned flight level in typical operational scenarios.

This understanding reveals why FL500 would not be an assigned flight level, as it falls outside the typical range where routine air traffic management occurs