How are cruising altitudes determined in Southern domestic airspace?

Cruising altitudes in Southern domestic airspace are determined based on magnetic track. This method aligns with the principles set out in aviation regulations that ensure safe vertical separation among aircraft flying along the same or intersecting flight paths.

Using magnetic track as the basis for altitude determination accounts for the Earth's magnetic variations and allows for standardized altitude assignments tailored to a specific geographic area. The altitudes assigned also correspond with the hemisphere relevant to the aircraft's magnetic track, ensuring that pilots maintain proper altitude relative to their navigation.

Determining altitudes using the true track or a combination of navigation and weather conditions can introduce variability that is less standardized, potentially leading to misunderstandings in altitude assignments. In addition, while the flight path of preceding aircraft is important for maintaining safety and separation, it is not a direct determinant for establishing cruising altitudes as it may change frequently and isn't an established parameter for altitude setting.