指南Airspeed Units Explained
Airspeed Units Explained
Convert knots, miles per hour, kilometres per hour, and metres per second for aviation and meteorology—without confusing airspeed types or nautical vs statute miles.
By the Units Converters editorial team · Voyager Tecnologias LTDA
Airspeed is a speed—with extra labels
Pilots talk about indicated airspeed (IAS), calibrated airspeed (CAS), true airspeed (TAS), and ground speed (GS). Those labels describe corrections for instrument error, altitude, and wind. Unit conversion (knots vs km/h) is separate: convert only after you know which airspeed type you are quoting.
Operational aviation prefers knots worldwide for airspeeds and winds. Popular articles may convert to mph or km/h for readers. Meteorology sometimes uses metres per second for wind. Know your audience before you change the number.
This guide focuses on unit conversion among knots, mph, km/h, and m/s. It does not replace performance charts or training on IAS/TAS relationships.
Knots as the aviation default
Airspeeds and ATIS winds are typically in knots. One knot = 1.852 km/h = about 1.15078 mph. When a POH lists V-speeds in knots, convert for a passenger explanation if you want—but memorize and fly the knot values you trained with.
Ground speed from GNSS is also often shown in knots in cockpit devices. A car-oriented app on a tablet may default to mph; switch units so your ETAs match sectional-chart thinking in nautical miles.
Nautical miles and knots travel together. If you convert speed to km/h, convert distance to kilometres too before dividing for time.
km/h, mph, and m/s in reports
Some civil documents and metric-country outreach use km/h. Convert knots → km/h by multiplying by 1.852. Example: 90 kt ≈ 166.7 km/h. For mph, multiply knots by about 1.15078.
Metres per second appear in scientific wind data and some European forecasts: 1 m/s = 3.6 km/h ≈ 1.94384 kt. A “10 m/s wind” is about 19.4 kt—not 10 kt.
Foot per second is rare in aviation ops but shows up in some engineering notes. Convert via m/s or mph using a speed converter rather than inventing factors mid-briefing.
Wind shear of the mental kind
Students sometimes convert a wind of 15 kt to “15 mph” by changing the label without changing the number. That understates wind. Always run the factor.
News may say “gusts of 80 mph” while METARs use knots. Re-convert from the authoritative METAR when briefing. Dual-unit sticky notes help in mixed classrooms.
Helicopter and ultralight communities sometimes speak mph in certain countries. Check the unit column on every performance table—especially when PDFs were scanned from mixed sources.
Linking speed to distance and time
Rule of thumb planning: time (hours) ≈ distance / speed when units match. Nautical miles with knots; kilometres with km/h; statute miles with mph. Crossing those streams is the main arithmetic failure in amateur flight planning.
Climb and descent rates use feet per minute—a vertical speed unit, not a horizontal airspeed unit. Do not convert fpm with knot converters.
Use knot ↔ km/h and m/s ↔ km/h tools to translate forecasts and stories, then return to knots for cockpit flows if that is your training standard.
實用清單
Identify the airspeed type (IAS/TAS/GS) and the unit. Convert the unit only. Keep type labels attached (“TAS 140 kt ≈ 259 km/h”).
Align chart distance units with speed units before ETA math. Verify tablet app unit settings before navigation practice.
When teaching mixed audiences, give knots first (ops truth) and a converted gloss second (public truth).
相關換算器
常見問題
Why doesn’t this guide use Mach?
Mach is a ratio to local speed of sound, not a fixed SI-style speed unit like knots or km/h. This converter set focuses on absolute speed units; use performance charts for Mach.
How do I convert knots to km/h?
Multiply knots by 1.852. Example: 100 kt = 185.2 km/h.
Is ground speed the same as airspeed?
No. Ground speed includes wind. You can convert either into km/h or mph, but they remain different physical quantities.