The rate of descent during a freefall skydive is primarily determined by the interaction between gravity and air resistance. After exiting the aircraft, the human body accelerates due to gravity’s pull. As velocity increases, the opposing force of air resistance, or drag, also intensifies. This drag acts against the downward motion, slowing the acceleration until a relatively constant speed is achieved.
Understanding the dynamics of descent is paramount for safety and control during the activity. Knowledge of these principles allows skydivers to manipulate their body position to adjust their fall rate. This is crucial for coordinating with other jumpers, executing maneuvers, and deploying the parachute at the correct altitude. Historically, advancements in skydiving techniques and equipment have been driven by a deeper comprehension of the physics governing freefall, leading to increased safety and the development of more sophisticated aerial skills.
This article will delve into the factors that influence the terminal velocity reached during freefall, examining the impact of body position, air density, and equipment used. Furthermore, it will explore techniques employed by experienced skydivers to control their rate of descent and navigate the sky effectively.
1. Gravity’s Acceleration
Gravity’s acceleration is the fundamental force initiating and influencing the rate of descent during a skydive. It is the driving factor behind the initial acceleration of a skydiver, directly influencing the speed at which they fall before air resistance becomes a significant factor.
-
Constant Acceleration in a Vacuum
In a vacuum, where air resistance is non-existent, gravity accelerates all objects at a constant rate of approximately 9.8 meters per second squared (m/s). This means an object’s downward velocity increases by 9.8 m/s every second. While a skydiver is not in a vacuum, this constant acceleration is the starting point for understanding the dynamics of the fall. For example, if only gravity were acting on a skydiver, their speed would increase linearly over time, reaching extreme and unsustainable velocities.
-
The Role of Mass
While gravity accelerates all objects equally in a vacuum, mass plays a role when considering air resistance. A heavier object experiences a greater force of gravity (weight), meaning it requires more air resistance to reach equilibrium (terminal velocity). However, the difference in fall rate due to mass alone is usually minimal for skydivers of typical builds, as body position and surface area have a more significant impact. A compact, dense object will fall faster than a larger, less dense one, given similar shapes.
-
Initial Acceleration Phase
Immediately after exiting the aircraft, the skydiver is primarily influenced by gravity’s acceleration. For the first few seconds, the velocity increases rapidly, and air resistance is still relatively low. This initial acceleration phase is crucial, as it sets the stage for the rest of the skydive. The skydiver’s body position during this phase can already influence how quickly they gain speed and the subsequent development of air resistance.
-
Reaching Terminal Velocity
Gravity’s constant acceleration is eventually counteracted by the increasing force of air resistance. As the skydiver’s speed increases, the drag force also increases. Eventually, the drag force equals the force of gravity, resulting in zero net force and no further acceleration. At this point, the skydiver reaches terminal velocity, a relatively constant speed of descent. While gravity is still acting on the skydiver, its effect is balanced by the opposing force of air resistance.
In conclusion, gravity’s acceleration initiates and strongly influences the speed of a skydiver during freefall. Its constant downward pull is balanced by air resistance, eventually leading to a stable rate of descent. Understanding gravity’s role is pivotal for skydivers to manage their freefall experience safely and effectively.
2. Air resistance (drag)
Air resistance, or drag, is a critical factor governing the velocity attained during a skydive. It opposes the force of gravity, ultimately determining the terminal velocity achieved in freefall. Its magnitude is influenced by several variables, each playing a distinct role in modulating the descent rate.
-
Drag Force and Velocity Squared
The force of air resistance is proportional to the square of the velocity. As a skydiver accelerates, the drag force increases exponentially. This relationship dictates that small increases in speed result in significant increases in drag, eventually counteracting the accelerating force of gravity. For example, doubling the speed quadruples the drag force, requiring a much greater gravitational force to achieve further acceleration.
-
Surface Area and Drag Coefficient
The surface area of the skydiver exposed to the airflow directly influences the drag force. A larger surface area creates greater resistance, slowing the descent. The drag coefficient, a dimensionless number, represents the object’s shape efficiency in generating drag. Streamlined shapes have low coefficients, while bluff bodies have high coefficients. For example, adopting a belly-to-earth position maximizes surface area, increasing drag and slowing the descent, while a head-down position minimizes surface area, reducing drag and accelerating the fall.
-
Air Density and Altitude
Air density decreases with altitude, impacting the magnitude of air resistance. At higher altitudes, the air is thinner, providing less resistance to the skydiver’s motion. This results in a higher terminal velocity compared to lower altitudes where the air is denser. A skydiver will accelerate more quickly and reach a faster terminal velocity at high altitude due to reduced air density. For example, skydives performed at extreme altitudes, such as those near mountains, require specialized equipment and techniques to manage the increased fall rate.
-
Turbulence and Stability
Air resistance is not uniform and can create turbulent airflow around the skydiver. Turbulence can affect stability and control during freefall. Skydivers manipulate their body position to create a stable airflow, minimizing unwanted rotations and deviations. A stable body position reduces drag fluctuations, leading to a more predictable and controlled descent. For example, maintaining a symmetrical body position minimizes asymmetric drag forces that could induce spinning or tumbling.
In conclusion, air resistance is the primary force that limits the acceleration of a skydiver, leading to the attainment of terminal velocity. Understanding the relationships between drag, surface area, air density, and body position is crucial for managing the speed and stability of descent during a skydive. These factors, in conjunction, determine how fast one falls when skydiving.
3. Body surface area
The exposed body surface area presents a primary determinant of the air resistance encountered during freefall, subsequently influencing descent velocity. An increase in the area facing the onrushing air results in greater drag, retarding acceleration and ultimately lowering the terminal velocity. Conversely, reducing the surface area diminishes air resistance, allowing for faster acceleration and a higher terminal velocity. The relationship between body surface area and descent speed is direct and predictable within standard atmospheric conditions.
The influence of surface area is apparent in the diverse range of body positions adopted by skydivers. Maintaining a flat, belly-to-earth orientation maximizes the surface area exposed to the airflow, generating substantial drag. This is a common position for beginners and tandem jumpers, prioritizing stability and a slower descent rate. Experienced skydivers, on the other hand, manipulate their bodies into streamlined configurations, minimizing surface area to achieve faster speeds for competitive disciplines such as speed skydiving. These techniques demonstrate the practical application of understanding surface area’s impact on descent.
Control over body surface area allows for nuanced adjustments to freefall velocity. By subtly altering limb position or arching the back, skydivers can fine-tune their descent rate to match other jumpers in formation or to optimize their approach to the deployment altitude. The effectiveness of these adjustments relies on a comprehensive understanding of the aerodynamic principles governing the relationship between body surface area and air resistance, highlighting the critical role of aerodynamic control. Mastery of surface area manipulation is crucial for both safety and advanced skydiving maneuvers.
4. Body orientation
Body orientation in freefall directly influences the rate of descent. The attitude of the body relative to the airflow dramatically alters the amount of air resistance encountered, providing a means to control vertical velocity during skydiving.
-
Belly-to-Earth Orientation
A belly-to-earth position, commonly employed by novice skydivers, maximizes the surface area exposed to the oncoming air. This orientation generates substantial drag, resulting in a relatively slow and stable descent. The increased drag minimizes acceleration, providing a safer and more controllable freefall experience, particularly beneficial for training and formation skydiving.
-
Head-Down Orientation
Conversely, a head-down orientation minimizes the surface area presented to the airflow. This streamlined profile reduces drag, allowing for significantly faster descent rates. This position is favored by competitive skydivers seeking to achieve maximum speed during freefall events. The head-down position demands greater skill and stability due to the reduced drag and increased sensitivity to aerodynamic forces.
-
Sit-Flying Orientation
Sit-flying involves maintaining a seated posture during freefall. This orientation presents a unique surface area and drag profile, offering a balance between speed and maneuverability. Sit-flying allows for controlled horizontal movement and intricate aerial maneuvers. The body’s vertical orientation impacts the airflow dynamics and influences the stability of the seated position.
-
Angle Flying Orientation
Angle flying utilizes the body as an airfoil, creating lift and allowing for controlled horizontal movement at an angle relative to the ground. This orientation manipulates the airflow over the body’s surfaces to generate lift and forward propulsion. The angle of attack and the body’s shape dictate the amount of lift and drag produced, influencing the speed and direction of travel. Proper execution requires precise body control and an understanding of aerodynamic principles.
In essence, body orientation is a critical factor determining the descent rate during freefall. By consciously adjusting body position, skydivers can actively manage their speed, stability, and direction, demonstrating the crucial link between body mechanics and aerodynamic control. These techniques allow for diverse skydiving disciplines and safe, controlled descents.
5. Air density variation
Air density variation constitutes a primary environmental factor that directly affects the velocity attained during a skydive. Changes in air density influence the magnitude of air resistance encountered by a falling body, subsequently altering the acceleration and terminal velocity experienced during freefall. The following points outline key aspects of this relationship.
-
Altitude and Air Density
Air density decreases exponentially with increasing altitude. As a skydiver descends from the exit altitude to lower levels, the surrounding air becomes progressively denser. This density increase results in a corresponding rise in air resistance. Therefore, a skydiver will initially accelerate more rapidly at higher altitudes due to lower air density and less drag. As they descend, the increasing density gradually reduces acceleration until terminal velocity is reached.
-
Temperature and Air Density
Temperature also impacts air density, although to a lesser extent than altitude changes during a typical skydive. Warmer air is less dense than cooler air at the same pressure. Consequently, on warmer days, a skydiver may experience a slightly faster initial acceleration and a somewhat higher terminal velocity compared to colder days at the same altitude, due to the reduced air density. This effect is generally less pronounced than the density changes experienced over the altitude range of a standard skydive.
-
Humidity and Air Density
Surprisingly, humid air is less dense than dry air at the same temperature and pressure. This is because water molecules are lighter than the nitrogen and oxygen molecules that make up the majority of the air. While the effect is relatively small, increased humidity can slightly reduce air density, leading to a marginally faster fall rate. This is most noticeable in extremely humid conditions.
-
Terminal Velocity Adjustments
Skydivers unconsciously and consciously adjust for air density variations. Experienced skydivers are aware that their typical freefall maneuvers and body positions will result in slightly different descent rates depending on the prevailing air density. Small adjustments to body position, such as altering the arch or limb placement, allow for fine-tuning of the descent rate to maintain coordination with other jumpers or to compensate for changes in air density during the descent. Understanding the influence of air density enhances precision in freefall maneuvers.
In summary, variations in air density, primarily due to altitude changes, significantly affect the forces acting on a skydiver during freefall. These variations influence acceleration and terminal velocity. While other factors, such as temperature and humidity, also play a role, the relationship between altitude and air density is the most dominant factor impacting the rate of descent when skydiving. Skilled skydivers are adept at accounting for these variations and adjusting their technique accordingly.
6. Altitude influence
Altitude exerts a significant influence on the velocity achieved during a skydive, primarily due to its inverse relationship with air density. The atmospheric conditions at varying altitudes directly affect the air resistance encountered, thereby modulating the speed of descent.
-
Air Density and Terminal Velocity
As altitude increases, air density decreases. This reduced density translates to lower air resistance, allowing a skydiver to accelerate more rapidly. Consequently, the terminal velocity, the point at which air resistance equals gravitational force, is higher at greater altitudes. For example, a skydiver exiting an aircraft at a higher altitude will initially experience a faster rate of acceleration and ultimately reach a higher terminal velocity compared to a jump from a lower altitude, assuming all other factors remain constant. This is a key factor in understanding the dynamics in how fast do you fall when you skydive.
-
Oxygen Availability and Physiological Impact
Higher altitudes are characterized by reduced oxygen partial pressure. While this may not directly impact the immediate descent rate, it can affect physiological function, especially during prolonged freefall. Decreased oxygen levels can impair cognitive function and physical stamina, potentially affecting a skydiver’s ability to maintain proper body position and control, indirectly influencing their speed and safety. This is something to note when discussing how fast do you fall when you skydive, since a physiological aspect can effect the speed or quality of the fall.
-
Temperature Variation and Airflow Stability
Temperature typically decreases with increasing altitude. This temperature gradient can influence airflow patterns, potentially affecting the stability of a skydiver during descent. Significant temperature differences can contribute to turbulence, which can alter the drag coefficient and consequently, the descent rate. A turbulent airflow can introduce unpredictable variations in speed, emphasizing the need for experienced skydivers to adapt to changing atmospheric conditions as part of how fast do you fall when you skydive.
-
Parachute Deployment Altitude and Deceleration
The altitude at which the parachute is deployed has a crucial influence on the overall descent profile. Deploying at a lower altitude means a shorter period of freefall at a higher velocity. Conversely, deploying at a higher altitude provides a longer period for controlled deceleration under the parachute. Accurate altitude awareness is essential for timely parachute deployment and a safe landing, and to know how fast do you fall when you skydive at different moments of this adventure.
In summary, the altitude from which a skydive commences significantly impacts the rate of descent through its influence on air density, physiological factors, and airflow stability. The interaction of these elements determines the velocity profile experienced during freefall and highlights the importance of considering altitude when planning and executing a skydive.
7. Parachute size
Parachute size is the ultimate determinant of descent rate during the final phase of a skydive, directly influencing the speed at which a skydiver approaches landing. It provides the primary mechanism for controlled deceleration following freefall, transitioning from terminal velocity to a safe touchdown speed.
-
Canopy Surface Area and Descent Rate
The surface area of a deployed parachute canopy is inversely proportional to the descent rate. A larger canopy generates greater drag, resulting in a slower, more controlled descent. Conversely, a smaller canopy produces less drag, leading to a faster descent. The relationship between canopy size and descent rate is fundamental to parachute design and selection.
-
Wing Loading and Landing Speed
Wing loading, defined as the skydiver’s weight divided by the parachute’s surface area, is a crucial factor determining landing speed. Higher wing loading corresponds to a faster landing speed, demanding greater skill and precision from the skydiver. Lower wing loading results in a slower, more forgiving landing. Experienced skydivers often choose smaller, high-performance canopies with higher wing loadings to enhance maneuverability and responsiveness, while beginners typically use larger canopies with lower wing loadings for increased safety and stability.
-
Parachute Type and Performance Characteristics
Various parachute types, such as ram-air, square, or elliptical canopies, exhibit different performance characteristics that influence descent rate and maneuverability. Ram-air canopies, commonly used in modern skydiving, are designed to act as wings, providing lift and allowing for precise control over descent speed and direction. Elliptical canopies offer even greater performance capabilities, enabling high-speed landings and advanced aerial maneuvers. The selection of a parachute type depends on the skydiver’s skill level, experience, and intended activity.
-
Pilot Skill and Landing Accuracy
Regardless of parachute size, the skydiver’s piloting skill is paramount for a safe landing. Proper canopy control, including the use of brakes and steering toggles, allows for precise adjustments to descent rate and direction. Accurate landing requires skillful maneuvering of the parachute to compensate for wind conditions and terrain features. Competent piloting minimizes the risk of injury during landing, regardless of the canopy’s size or performance characteristics.
In summary, parachute size exerts a definitive influence on the final descent rate, dictating the speed at which a skydiver transitions from freefall to landing. Wing loading, parachute type, and piloting skill all interact to determine the overall safety and success of the landing, demonstrating the intricate relationship between equipment and human factors in mitigating the potential risks associated with how fast one falls during this critical phase of the skydive.
8. Equipment weight
Equipment weight, while seemingly a minor factor, contributes measurably to the overall mass subjected to gravitational acceleration during a skydive, thereby influencing descent velocity. The aggregate weight of the parachute system, jumpsuit, helmet, and any ancillary devices affects the terminal velocity attained during freefall and the subsequent descent rate under canopy.
-
Impact on Terminal Velocity
An increase in equipment weight directly raises the force of gravity acting on the skydiver, necessitating a corresponding increase in air resistance to achieve equilibrium, or terminal velocity. This implies that a skydiver with heavier equipment will experience a slightly higher terminal velocity compared to an individual with lighter gear, given identical body positions and atmospheric conditions. The difference, while potentially subtle, becomes relevant in scenarios such as formation skydiving, where precise control over descent rates is crucial.
-
Influence on Parachute Performance
Equipment weight affects the wing loading of the deployed parachute, defined as the total weight supported by the canopy’s surface area. Higher wing loading, resulting from increased equipment weight, generally translates to faster flight speeds and more responsive handling under canopy. However, it also necessitates more precise piloting skills and increases the potential for a harder landing. Skydivers must select parachute sizes appropriate for their total weight, including equipment, to ensure safe and controllable descent.
-
Considerations for Body Weight Adjustments
Equipment weight contributes to the overall mass that skydivers must manage through body position. It is crucial for maintaining stability and controlling airspeed in various skydiving disciplines. For a given equipment configuration, an increase in body weight would have a very similar affect to an increase in equipment weight. Skydivers often consciously adjust their posture and limb positioning to counteract the effects of added weight, maintaining the desired descent rate and directional stability.
-
Material Science and Weight Reduction
Advancements in material science have led to the development of lighter and stronger skydiving equipment. Manufacturers continuously strive to minimize the weight of parachute systems and jumpsuits without compromising safety or durability. The adoption of lightweight materials, such as advanced polymers and alloys, allows skydivers to reduce their overall load, potentially improving maneuverability and reducing fatigue during prolonged freefall and canopy flight. However, material choice is a balance of durability, safety, and price.
In conclusion, equipment weight, though not the most dominant factor, plays a tangible role in shaping the dynamics of how fast one falls during a skydive. Its influence extends from terminal velocity in freefall to the performance characteristics of the deployed parachute. Awareness of this influence is critical for safe equipment selection, effective body position adjustments, and ultimately, a controlled and successful descent.
9. Terminal velocity
Terminal velocity represents a critical concept in understanding the rate of descent during a skydive. It signifies the point at which the force of gravity is precisely balanced by the opposing force of air resistance, resulting in a constant velocity. This equilibrium is not static but is dynamically influenced by a complex interplay of factors.
-
Equilibrium of Forces
Terminal velocity occurs when the downward force of gravity equals the upward force of air resistance. Initially, a skydiver accelerates due to gravity. As velocity increases, so does air resistance. Eventually, the air resistance force becomes equal to the gravitational force. At this point, the net force is zero, and acceleration ceases. The skydiver then falls at a constant speed. This balance is key in illustrating how fast do you fall when you skydive.
-
Influence of Body Position
Body orientation significantly impacts terminal velocity. A streamlined, head-down position minimizes air resistance, leading to a higher terminal velocity, potentially reaching speeds of 150-200 mph. Conversely, a flat, belly-to-earth position maximizes air resistance, reducing terminal velocity to approximately 120 mph. Skydivers manipulate their body position to control their rate of descent. These techniques exemplify how fast do you fall when you skydive, depending on skill and experience.
-
Air Density and Altitude
Air density, which decreases with altitude, directly affects terminal velocity. At higher altitudes, thinner air offers less resistance, resulting in a faster terminal velocity. This is crucial in high-altitude skydiving, where specialized equipment and techniques are employed to manage the increased speeds. This illustrates a vital element of how fast do you fall when you skydive, in the face of different environmental conditions.
-
Equipment and Weight
The weight of the skydiver and their equipment also influences terminal velocity. A heavier skydiver experiences a greater gravitational force, requiring a greater air resistance force to reach equilibrium. This results in a higher terminal velocity. Similarly, adding weight, like additional equipment, will incrementally increase descent speed, directly impacting how fast do you fall when you skydive.
In conclusion, terminal velocity is a dynamic state dictated by the interplay of gravitational force, air resistance, body position, air density, and equipment weight. Understanding these factors is paramount for skydivers to safely and effectively control their descent rate and execute complex maneuvers during freefall and is essential to understanding the principles underpinning how fast do you fall when you skydive.
Frequently Asked Questions About Freefall Velocity
The following questions address common inquiries regarding the speed of descent during a skydive, providing concise explanations of the underlying factors.
Question 1: At what speed does an average skydiver typically fall?
The typical vertical speed achieved during a freefall skydive is approximately 120 miles per hour (193 kilometers per hour). This speed, known as terminal velocity, represents the equilibrium between gravitational force and air resistance for a skydiver in a belly-to-earth orientation.
Question 2: Does body weight significantly affect the rate of descent?
While body weight does influence the rate of descent, the effect is less pronounced than factors such as body position and air density. A heavier individual will experience a slightly higher terminal velocity, but this difference is often minimal compared to the impact of aerodynamic adjustments.
Question 3: How does altitude impact freefall velocity?
Altitude has a direct influence on freefall velocity due to its inverse relationship with air density. At higher altitudes, the air is thinner, offering less resistance. Consequently, a skydiver will accelerate more rapidly and reach a higher terminal velocity compared to a skydive from a lower altitude.
Question 4: Can skydivers control their speed during freefall?
Skydivers possess the ability to actively control their descent rate through adjustments to their body position. Manipulating body orientation and surface area allows for precise modulation of air resistance, enabling controlled increases or decreases in vertical velocity.
Question 5: What role does equipment play in influencing descent speed?
The weight and aerodynamic properties of skydiving equipment contribute to the overall forces acting on the skydiver. Heavier equipment increases the gravitational force, resulting in a slightly higher terminal velocity. Aerodynamic design can affect the drag coefficient, further influencing descent speed.
Question 6: How does parachute deployment affect the descent rate?
Deployment of the parachute dramatically reduces the descent rate. The large surface area of the parachute canopy generates substantial drag, decelerating the skydiver from terminal velocity to a safe landing speed. Parachute size and design directly determine the final rate of descent under canopy.
In summary, a skydiver’s speed is a result of multiple interacting factors. This knowledge is useful for skydiving enthusiasts.
The subsequent section will focus on safety measures.
Safety Tips for Managing Freefall Speed
Maintaining control over the rate of descent during a skydive is paramount for safety and coordination. The following tips emphasize crucial aspects of managing freefall speed to mitigate risks and enhance the overall experience.
Tip 1: Maintain Awareness of Altitude:
Regular altitude checks are essential throughout the skydive. Utilizing an audible altimeter or visually referencing the ground provides critical information for timely parachute deployment. Neglecting altitude awareness can lead to dangerously low deployments or failure to deploy, increasing risk exponentially.
Tip 2: Employ Proper Body Position:
Adopting a stable, belly-to-earth position maximizes surface area and increases air resistance, resulting in a slower and more controllable descent. Avoid sudden or erratic movements that can disrupt stability and lead to unintended acceleration. This position allows the individual to have a good understanding of how fast do you fall when you skydive.
Tip 3: Monitor Airspeed and Adjust Accordingly:
Be cognizant of the sensation of airspeed and make subtle adjustments to body position to maintain a consistent rate of descent. Arching the back or extending limbs can increase drag, while streamlining the body reduces drag. This continuous adjustment optimizes the desired fall rate, and an awareness of how fast do you fall when you skydive.
Tip 4: Coordinate with Other Jumpers:
When skydiving with others, communication and coordination are vital. Establish a clear understanding of the planned formation and descent rate prior to exiting the aircraft. Regularly check your relative position to other jumpers and adjust your speed as needed to maintain proximity and avoid collisions. If any accidents happen it has be discussed openly. Proper planing and the awareness of how fast do you fall when you skydive is very crucial for this tip.
Tip 5: Respond to Turbulence:
Turbulence can cause sudden changes in airspeed and direction. Recognize the signs of turbulent air and react promptly by tightening your core muscles and making small, controlled adjustments to your body position. This stabilizes the body and minimizes the impact of erratic airflow. The awareness of how fast do you fall when you skydive is very important for this tip.
Tip 6: Practice Emergency Procedures:
Familiarize yourself thoroughly with emergency procedures, including malfunction recognition and reserve parachute deployment. Regular practice, both on the ground and in simulated freefall environments, builds muscle memory and ensures a swift and decisive response in the event of an emergency. These training sessions can give you an awareness of how fast do you fall when you skydive.
Tip 7: Get Enough Education from the Experts:
Before diving into the actual adventures, make sure to get as much information and trainings. This will give you a better view on the potential issues that can happen and how to deal with them, in addition to the awareness of how fast do you fall when you skydive.
Adhering to these safety tips enhances control, minimizes risk, and contributes to a more enjoyable and successful skydiving experience. Prioritize safety to fully appreciate the exhilaration of freefall.
The following section will provide concluding remarks.
Conclusion
This article has explored the multifaceted nature of “how fast do you fall when you skydive.” It has examined the interplay of gravity, air resistance, body surface area, body orientation, air density, altitude, equipment weight, and parachute size, ultimately converging on the concept of terminal velocity. Each of these factors contributes to the overall rate of descent during a skydive, and understanding their influence is paramount for both safety and skillful execution.
The information presented serves to underscore the importance of continuous learning and adherence to safety protocols within the skydiving community. A commitment to mastering these principles enables skydivers to manage the risks inherent in the sport and to experience the unique freedom of controlled freefall, and to know how fast do you fall when you skydive in any situation. Further research and technological advancements will continue to refine our understanding of the physics governing descent, leading to safer and more innovative skydiving practices.
