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Airspeed and ground speed represent two distinct measurements in aviation. Airspeed calculates how fast an aircraft moves through the air, whereas ground speed determines its movement over the Earth's surface, including the influence of wind. Greg Bajor/Getty ImagesKey Insights
- Airspeed refers to the speed of an aircraft relative to the surrounding air, whereas ground speed measures how fast it moves across the ground, considering wind speed as a factor.
- A strong tailwind can push the aircraft's ground speed to exceed its airspeed.
- Airspeed isn't just critical for aviation—it also influences fuel efficiency in vehicles on land, offering a more precise understanding of actual travel speed and efficiency than speedometer readings.
In February 2019, a Virgin Atlantic Boeing 787 jet, traveling from Los Angeles to London and flying over Pennsylvania, achieved an impressive speed of 801 miles per hour (1,289 kilometers per hour), as reported by CBS News.
However, the record-breaking speed wasn't due to the aircraft itself being unusually fast. Much like a sprinter benefiting from a tailwind, the plane took advantage of an extraordinarily swift jet stream, a powerful wind moving at 231 miles per hour (371.7 kilometers per hour). This jet stream was the fastest seen in over six decades.
As detailed by CBS News, this resulted in the 787 flying much faster than its normal cruising speed of 561 miles per hour (902.8 kilometers per hour).
This example illustrates the difference between airspeed and ground speed.
As explained in this explainer on NASA's website, ground speed refers to how quickly an airplane moves in relation to a fixed point on the ground. To visualize this, imagine how fast an airplane's shadow would move across the land. Strong winds impacting the plane are reflected in its ground speed.
Airspeed, on the other hand, measures the actual speed at which an airplane is flying using only its own power. It is calculated by subtracting the wind speed from the ground speed. NASA clarifies:
Airspeed influences more than just airplanes; it also has an impact on ground vehicles. A study published in the 2013 issue of the International Journal of Energy and Environmental Engineering highlights that a car's airspeed on the road is the true factor determining its fuel efficiency, not the ground speed or the reading on the speedometer.
As NASA notes, a kite has a ground speed of 0 miles per hour, since it is held by a string. However, since it moves through the air, its airspeed matches the wind's speed.
