When do cruising altitudes shift to True track?

Cruising altitudes are expressed in terms of true track for aircraft operating in Northern domestic airspace. This practice ensures that navigators can maintain accuracy when translating vertical positioning because the Earth's curvature affects the direction of true north, particularly in higher latitudes.

Above 24,000 feet ASL, although it is a point where airspace regulations become more complex and may include performance-based navigation considerations, the key point regarding transitioning to true track is specifically about the Northern domestic airspace rules. This transition helps with route planning and may also be influenced by variations in magnetic declination as aircraft proceed north, where magnetic north can differ significantly from true north.

Understanding this concept is vital for ensuring compliance with airspace regulations and for effective flight navigation in diverse geographical regions.