Hard Openings and How to Avoid Them

By Jim Crouch

Safety & Training
Friday, February 5, 2021

A hard-opening parachute is certainly not a new phenomenon. Skydivers have been dealing with hard openings throughout the history of sport parachuting—particularly during the early 1970s when the first ram-air main canopies and the various devices used to try and tame their openings were developed. One of those was the slider, which greatly improved the quality and reliability of ram-air deployments. Although there have been some variations in size and construction, the basic concept and design of the ram-air parachute slider has gone unchanged for decades.

However, even after the slider came into play, hard-opening parachutes have continued to be a pretty consistent problem. It’s not unusual on any given weekend at the drop zone to hear at least one jumper complaining of a whacker of an opening while rubbing their neck. Thankfully, most hard openings are tolerable, even though they can be painful.

While the definition of a hard opening can be subjective, the results of a hard-opening parachute can range anywhere from an uncomfortably quick opening that results in light bruising and soreness to a brutally hard, instant opening that results in severe or even fatal injuries. Several factors determine the speed of an opening:

• Parachute design and materials
• Suspension line types
• Condition of the parachute equipment
• Pilot chute size and design
• Packing procedures
• Body position and deployment speed

The age and physical condition of the jumper also comes into play. As people age, the human body simply does not hold up well to a lot of physical abuse. A hard opening that is survivable for a 30-year-old jumper might be fatal for a 65-year-old.

Last year, the U.S. Parachute Association asked the Parachute Industry Association to look into the issue of hard-opening parachutes and provided the Technical Committee with some statistical information collected by USPA over the past 20 years:

• A hard-opening main or reserve parachute caused 18 known fatal accidents
• 14 of those fatalities involved jumpers who were 59 years old and older
• In 2019, three older jumpers died from hard openings. Based on the jump numbers for jumpers who are 60 and older, this means one fatality for every 133,056 jumps.

As far as fatal accidents go, the chances of dying from a hard-opening parachute are pretty low, especially for jumpers younger than 60 years old. However, there are a lot of jumpers who are seriously injured by hard openings every year. Because of a lack of reporting these non-fatal accidents over the years, there is no way to know exactly how many jumpers have been injured this way. It is a safe bet that there are several if not dozens of hard openings across the U.S. every weekend, and USPA needs that data. USPA has made it easy to report fatal and non-fatal incidents with an online form at uspa.org/ir.

Canopies and Suspension Lines

As parachute materials and designs changed over the decades to improve flight characteristics and performance, the severity of hard openings when those parachutes did not deploy correctly also increased. Up until the early 1990s, most parachutes were constructed from low-porosity ripstop nylon (usually called F-111), which is a material that allows some air to pass through but becomes more porous as jumps accumulate. The openings tend to get slower and softer as the parachute ages, and the chances of a hard opening get pretty low. At least one manufacturer used to recommend cutting a hole in the slider to speed up the openings as the canopy aged!

Beginning in the early ‘90s, manufacturers began making parachutes from zero-porosity material (commonly called zero-p). Zero-p has a coating that prevents any air from passing through the material. Not only did it improve the performance of the parachute, it also increased the lifespan. But it amplified the effects of a hard opening.

Suspension-line technology was also changing. Dacron, which is a brand name for a polyester material manufactured by DuPont, offers some protection against a hard opening. The line stretches during deployment, acting as a shock absorber to lessen the impact on the body in the event of an instant-opening parachute. But Dacron is a somewhat bulky line compared to the other types of suspension line available now. It also does not hold up well against wear from abrasion. Manufacturers began to move away from Dacron in favor of Spectra, Vectran and HMA (High-Modulus Aramid), which are stronger and smaller in diameter. However, these lines do not stretch during the parachute deployment, creating what one container manufacturer has described as “steel cables” connecting the parachute to the risers. In the event of a hard opening with non-stretching suspension lines, the forces transmit directly to the harness (and jumper’s body).

Over a relatively small number of jumps, Spectra suspension line begins to shrink due to heat generated by friction with the slider grommets as they slide down the lines during a deployment. The outer suspension lines and the brake lines heat up more than the inboard suspension lines, causing the parachute to lose its trim, bowing more at the edges as the jump numbers accumulate. HMA and Vectran hold their trim very well but can break without warning due to wear that is difficult to detect. Each type of suspension line has pros and cons, so it is a good idea to discuss the issue with your rigger or the manufacturer when it comes time to order a new parachute or reline your current parachute. You might decide that a different line type is more suitable for your individual needs. 

Longtime Federal Aviation Administration Master Rigger and Designated Parachute Rigger Examiner Kevin Gibson cautions that line trim and the type of suspension line are important elements when it comes to parachute openings, saying, “During a PIA Symposium presentation, Rusty Vest of Performance Designs told a group that for reasons nobody understood (at least at that time), when a canopy works its way out of trim, it seems to exhibit problems suddenly. It’s not that it starts to open harder and harder but instead seems fine and then, wham! I believe it’s possibly because an out-of-trim canopy is more sensitive to poor slider placement.

“If the slider’s initial presentation to the air is off-balance, it will lose its inflation and sail down the lines with very little drag under the force of spanwise inflation. Keep in mind that the outside lines have been foreshortened, creating a pronounced doming effect on the bottom skin. It is interesting that creating just a slight doming on the slider itself meters the opening by holding the slider up against the stops and so it comes down more gradually.

“I don’t know, but I would hypothesize that the same doming effect on the planform would increase the inflation forces that the slider is meant to ameliorate. A poorly packed slider or a shoulder-low opening could be all it takes to spill all the air out of the slider and force it down the lines with little more than the friction of the grommets to resist. There is also the possibility of the slider acting like a jib on a sailboat, where once one edge gets ahead of the opposite edge, a high-pressure/low-pressure condition results and actually increases the slider’s downward progress. The point is that almost all canopies with modern lines need relining at about 450-550 jumps, regardless of line type, but just for different reasons.”

Pilot Chutes and Deployment

Jean Potvin and the late Gary Peek of the Parks College Parachute Research Group have researched parachute-opening characteristics and documented the testing they have performed over the years. A 2008 document at pcprg.com/sliderdragcancel.pdf provides a lot of useful information explaining why a parachute can occasionally and unexpectedly open very hard. The document theorizes that in rare cases, high-pressure airflow enters between the parachute and the slider during the deployment, resulting in a slider zinging down the suspension lines toward the risers at an accelerated rate, canceling any effect of the slider slowing down the inflation of the parachute. It is not unusual to find burn damage on the slider and suspension lines after a hard opening due to the high heat generated when the slider races down the suspension lines. Peek also experimented with using larger sliders to tame hard opening parachutes, which he documented at pcprg.com/hardop.htm.

Fernando Caralt, the director and design engineer with Icarus World, works carefully to develop canopies that provide smooth and consistent openings under a wide range of conditions. But he notes that situations like opening at higher altitudes or faster deployment speeds can cause the canopy to open harder. He also notes that any deployment that is not symmetrical (as noted by Potvin and Peek) can lead to a hard opening.

According to performancedesigns.com/docs/hrdopn.pdf released by Performance Designs in 2004, “The size, type of fabric, length of bridle, apex length, mesh size, and aerodynamic shape all affect the deployment of the parachute. Some pilot chutes have too much drag at terminal velocity. This can cause these problems:

• They slow the bagged canopy down so quickly that the chance of line dump is increased.
• When reaching line stretch, the jumper instantly accelerates the canopy back to his speed, since it is attached to him by the fully deployed lines.

“This is the first force the jumper feels at line stretch. (Moments later, the canopy starts to fill with air and slows down again.) A pilot chute with too much drag will have slowed the bagged canopy down so much that the jumper will experience quite a strong force when the canopy reaches line stretch. The canopy feels this jolt too, and the pack job will be forcefully spread apart by this force. This can cause harder openings, since the now-disorganized canopy will inflate more quickly. In extreme cases, it may even open hard enough to cause structural damage to the parachute system, bodily injury or death.”

Symmetry also plays an important role in the deployment sequence. The deployment bag must lift out of the container squarely to help ensure that the line stows release evenly. Something as simple as dropping a shoulder during deployment or one riser cover that stays closed longer than the other during a deployment can result in uneven suspension lines as the deployment bag reaches line stretch. This can lead to line twists or hard openings. It also helps to slow down as much as possible before the deployment. Altitude permitting, flattening out your torso to slow down at the end of a track before throwing the pilot chute can help to soften the opening of the parachute.

Packing the Parachute

Most industry experts agree that packing errors are largely the cause of nearly every catastrophic hard opening. Two of the hard-opening fatalities documented since 2000 involved heavier jumpers who deployed reserve parachutes while falling at speeds in excess of 170 miles per hour. So not only were the reserves overloaded, they were also deployed at excessive speeds. The other 16 fatalities involved main-parachute deployments that were instantaneous.

While there are several key factors involved in a parachute deployment that help to ensure the parachute opens properly, packing the parachute according to the manufacturer’s instructions is the best way to ensure it. T.K. Donle, chairman of the PIA Technical Committee, says that it is understood by industry experts that the method of line stowing is crucial to controlling the deployment. “Given what the industry knows of parachute deployments in general, it’s clear that multiple causes exist for hard openings. Any one of them, or a combination of them, could yield a hard opening.

• Equal and constant suspension-line tension while packing.  (If not, tension knots might occur, which can cause severe opening shocks.)
• Length of the line bights stowed on the bag.  (If line bights are too short and release prematurely, this can cause line entanglements or line dump, which may lead to out-of-sequence deployments, meaning partial canopy inflation before full line stretch.)
• Single and/or double-stowed line bights.  (When line-bight extraction forces are too low, all the problems listed above can occur.  When they’re too high, bag locks can occur, followed by a terminal reserve deployment.)
• Line-bight extraction force:  Follow manufacturer guidance if they provide it, though very few actually do.  (Performance Designs promotes 8-12 pounds for solo systems.)”

The proper stowing of suspension lines helps ensure that the lines have fully extended before the deployment bag opens and the bottom of the parachute is exposed to the relative wind. Brutally hard openings are usually caused by a deployment that occurs out of sequence. Still photos and videos of deployments have shown all of the line stows releasing as soon as the container flaps are open and the main bag begins to lift out of the pack tray, allowing the deployment bag to then be stripped off the canopy while the suspension lines are slack. The result is a disorganized canopy that inflates instantaneously. The forces applied to the harness and jumper during that type of deployment are usually pretty brutal. Semi-stowless deployment bags, however, seem to be providing good results. The key to that design is there must be secure locking stows on at least two bights of suspension line that ensure the deployment bag remains securely around the canopy until the suspension lines have fully extended.

Whether you use conventional line stowing, or a semi-stowless main bag, the suspension lines need to unstow in an orderly fashion. The rubber bands must hold each line bight with enough tension to allow for release at the correct time. Only when all of the stows have released and the suspension lines are fully extended should the main bag come off of the canopy to expose the slider to the relative wind once the tail is unwrapped from around the bottom of the parachute.

Once the lines unstow and the canopy clears the deployment bag, it is critical that the slider has been placed correctly into the pack job. John LeBlanc, vice president of Performance Designs, has spent decades designing and testing parachutes. In the video titled “Hard Openings: A Discussion with John LeBlanc,” he speaks quite a bit about the importance of slider placement: “In order for the slider to do its job properly, it has to start in the right place. The basics of that means it has to be right up against the slider stops. Also, it’s wise to quarter the slider, so that as the four line groups start to separate from one another early on in the deployment of the canopy, the slider is right there in the middle, ready to do its job.” The 16-minute video is well worth the watch and includes lots of great information. You can find the video at tinyurl.com/hardopenings.

Age and Physical Condition

Statistics indicate that age is a major factor in determining whether a severely hard opening results in an injury or a fatality. Studies in aging show that the human body changes with age at the molecular level, resulting in organs and connective tissue that become more rigid and stiff. According to the U.S. National Library of Medicine, “As aging continues, waste products build up in tissue. A fatty brown pigment called lipofuscin collects in many tissues, as do other fatty substances. Connective tissue changes, becoming more stiff. This makes the organs, blood vessels and airways more rigid. Cell membranes change, so many tissues have more trouble getting oxygen and nutrients and removing carbon dioxide and other wastes.”

One potential cause of a fatality due to a hard opening is a torn aorta. Age plays a large part in whether the aorta can withstand the blunt-force trauma inflicted on the body during a hard opening. The dynamics of a person experiencing a torn aorta from an auto accident are similar: The body is abruptly stopped—by the seat belt in a car or the harness during a parachute jump—while traveling at speed, but the internal organs keep moving. If the flexibility of the aorta has deteriorated with age, the result can be fatal. Simply put, older jumpers have a greater chance of experiencing fatal injuries in the event of a hard opening. It is certainly something that older jumpers need to consider.

At best, a hard-opening parachute can make for a sore body and an unhappy jumper. At worst, it can cause a serious injury or fatality. There is a lot to consider when it comes to avoiding a hard opening. But proper maintenance and correct packing procedures are two of the biggest factors that the jumper can control when it comes to avoiding a whacker of an opening. It will help you enjoy a long and happy skydiving life without the need of Ibuprofen and neck massages.

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About the Author

In addition to losing several friends to fatal hard openings, Jim Crouch, D-16969, has had his own share, two of which changed his life significantly. A hard opening in 1995 resulted in an undetected malfunctioned steering line on one side of the parachute, and he crushed a vertebra from the hard landing. In 1998, another hard opening broke his neck, resulting in a scary several seconds of paralysis from the neck down. (Luckily, movement and feeling came back after a few seconds and the landing was uneventful.) Both hard openings occurred while wearing 15-pound camera helmets, which amplified the forces put on his neck and spine. Today, he needs only to turn his head for the snapping and popping noises to remind him of those incidents.