The speed at which a person falls from an airplane changes the moment a parachute opens. Before deployment, a skydiver in a stable, belly-to-earth position can reach a terminal velocity of approximately 120 miles per hour (193 kilometers per hour). The parachute’s function is to interrupt this rapid descent, creating a massive increase in drag that slows the fall to a fraction of the freefall speed. This controlled rate of descent is a variable range influenced by the type of canopy, the total weight suspended below it, and the atmospheric conditions.
Typical Descent Speeds with an Open Parachute
For modern recreational skydiving using a ram-air canopy, the typical vertical descent rate stabilizes in a relatively narrow range. An average descent speed for a skydiver under a standard sport canopy is approximately 10 to 17 miles per hour (16 to 27 kilometers per hour). This speed is slow enough to allow for a soft landing, especially when the skydiver executes a final flare, which temporarily reduces the vertical speed to near zero just before touchdown.
Ram-air canopies are designed to glide forward, much like an aircraft wing. These wings can achieve a significant horizontal forward speed, often reaching 20 to 25 miles per hour (32 to 40 kilometers per hour), depending on the canopy design. This forward motion allows the skydiver to steer and land precisely at a target location.
The older, less maneuverable round parachutes, often used for cargo drops or some military operations, offer a more fixed rate of fall. These canopies are designed purely for stability and drag, resulting in a slightly higher average vertical descent rate in the range of 12 to 15 miles per hour (19 to 24 kilometers per hour). Since these parachutes offer little to no forward steering, the landing impact is generally less cushioned than with a modern sport canopy.
The Physics of Controlled Descent: Achieving Terminal Velocity
The constant downward force is gravity, which pulls the skydiver and all their equipment toward the Earth. The opposing upward force is air resistance, or drag, which is the friction created by the air pushing against the falling object.
In freefall, the relatively small surface area of the human body generates a limited amount of drag, only enough to balance gravity at a high terminal velocity of around 120 miles per hour. When the parachute deploys, it introduces a massive surface area of fabric, which exponentially increases the amount of air resistance. This sudden and intense increase in drag rapidly decelerates the falling mass from freefall speed.
The descent reaches a controlled, constant speed when the upward force of air resistance perfectly equals the constant downward force of gravity. This point of equilibrium is known as the terminal velocity under canopy. Because the parachute is so efficient at creating drag, this new, slower terminal velocity is reached quickly and maintained throughout the majority of the descent.
The physics of a ram-air parachute is slightly more complex, as its rectangular shape acts as an airfoil to generate lift, similar to an airplane wing. This lift force is angled, contributing a small upward component that further counters gravity, while the forward movement generates significant horizontal speed. The combined effect of drag and lift is what allows these canopies to be steered and manipulated to glide, giving the skydiver control over the final descent path.
Variables Influencing Final Speed
The actual speed of descent is not uniform, even under the same model of parachute, because the final rate is determined by a ratio of factors. One of the most significant variables is the total suspended weight, which includes the skydiver, their gear, and the parachute itself. A heavier total mass requires a higher velocity to generate the necessary amount of air resistance to balance the increased gravitational pull.
This relationship is quantified by a measurement known as “wing loading,” which is the ratio of the total weight to the surface area of the parachute canopy. A skydiver with a high wing loading—meaning a heavy load under a relatively small canopy—will fall faster than a lighter person under a larger canopy. Higher wing loading results in higher speed and greater responsiveness, which is often preferred by expert skydivers.
The design and size of the canopy also play a fundamental role in determining the final speed. Large, low-performance canopies, often used for student training or tandem jumps, are designed to generate maximum drag and will descend at the slower end of the speed range. Conversely, small, high-performance elliptical canopies are designed to be aerodynamic and fast, allowing their pilots to intentionally dive and achieve descent speeds well above the average, sometimes exceeding 60 miles per hour (96 kilometers per hour) for advanced maneuvers.
Atmospheric conditions, particularly air density, also affect the terminal velocity. Air at sea level is denser than air at higher altitudes, meaning it provides greater air resistance for the same amount of surface area. A descent through thinner air at very high altitudes will result in a slightly faster rate of fall because the air offers less drag to counteract gravity.