The Iron Law of Vertical Separation: Keeping the Skies Stacked Safely
Vertical separation is the non-negotiable vertical buffer between aircraft in controlled airspace—the invisible spacing that prevents mid-air collisions when lateral or longitudinal separation cannot be guaranteed. In most controlled airspace worldwide, the baseline standard remains 1,000 feet (≈300 metres) below FL290 (29,000 ft). This applies across the lower and mid-levels where the majority of traffic…

