What is the altitude and distance for a Marshall Stack holding pattern?

The Marshall Stack holding pattern is defined by specific distance and altitude parameters that are crucial for maintaining safe flight operations in a controlled airspace environment, particularly for aircraft awaiting approach to an airfield. The correct choice indicates that the holding pattern is to be established at an altitude of 6,000 feet and a distance of 21 nautical miles from the designated point.

This setup allows for an adequate buffer between the aircraft and the airfield, ensuring safety and efficiency as aircraft enter the terminal airspace for landing procedures. The altitude provides sufficient vertical separation from surrounding air traffic and terrain, while the specified distance ensures that the aircraft are appropriately spaced out for communication, navigation, and traffic avoidance as they prepare to land.

These parameters are established by regulations and standard operating procedures to ensure safety and efficiency in air traffic management.