Why Knots Persist in Aviation and Maritime Use
Most speed units (km/h, mph, m/s, ft/s) are straightforward ratios of a distance unit to a time unit, but the knot is defined differently: one knot is one nautical mile per hour, and a nautical mile itself is defined as one minute of latitude (1/60th of a degree) along a great circle — a definition tied directly to Earth's geometry and navigation, not an arbitrary distance-per-time ratio like the other units.
This geometric definition is exactly why knots remain the standard in aviation and maritime navigation specifically: a vessel or aircraft's speed in knots relates directly and conveniently to distance covered on a navigational chart measured in degrees and minutes of latitude, which is a genuinely practical advantage for chart-based navigation that km/h or mph don't share, despite being perfectly good speed units for other contexts.
Converting between knots and more common units like km/h or mph isn't a round-number relationship (1 knot is approximately 1.852 km/h or about 1.151 mph) — a detail worth knowing before assuming a "close enough" mental approximation is safe for anything where the actual speed value has real navigational or regulatory significance.