关于备份伞的设计和选择

Emergency parachutes for free flight do really work. Since 1977, when Jim Handbury had the idea of attaching an emergency parachute to a hang glider and it's pilot, thousands of pilots' lives have been saved.
自1977年Jim Handbury（吉姆汉德勃瑞）开始将应急备份伞应用到悬挂滑翔以来，数以千计的飞行员的生命得以挽回。
The important thing about parachutes is to have one when you need one.

The second most important thing is that it works when you need it to.
关于备份伞最重要的两件事情就是：
1．当你需要的时候，你有一个
2．当你需要使用的时候，它的确发挥作用了

In France, especially among paragliders, a large number of pilots still do not fly with a parachute. Rather than make it mandatory to fly with a parachute (which is quite useless because it's almost impossible to enforce), it's more important to change the outlook of pilots. Instructors should institute the use of helmet and back protection from the very first practice sessions at the training hill, and use of a parachute as of the first flight. This way, new pilots learn to regard these items of safety equipment as indispensable, and those who fly without, instead of being seen as 'cool', should come to be regarded as poor fools.
在法国，尤其是在滑翔伞飞行员当中，有相当数量的飞行员仍然不愿意携带备份伞飞行；与其强制所有飞行员携带备份伞（其实也没啥用，因为几乎不具可实施性），不如逐渐改变飞行员的观念。教练应该在培训开始的时候就教会新手注意安全，必须使用头盔和背部保护（译者注：即不要使用斗伞用的简易吊带进行飞行），以及从第一次飞行就开始携带备份伞，建立备份伞是飞行必备之物的观念。让那些曾经觉得不带备份伞飞行是很酷的飞行员认识到不带备份伞飞行是很可怜的傻瓜干的事情。
There is much discussion about emergency parachutes, and for those who are not professional in the field, it is very difficult to sort out the claims forwarded by the 'experts'. Since we speak here of a critical safety issue, it is necessary for all questions to be given a satisfactory answer. Instead of just giving my own solutions to the various problems surrounding use of emergency parachutes, I think it best to provide an overview of all points so that each pilot can formulate his or her own thoughts and judgement.
现在有很多关于备份伞的讨论，对于非专业人士而言，很难分辨那些"专家"的主张。由于备份伞是一个性命悠关的东西，所以有必要对所有的问题进行满意的解答。这里我并不是要给出我自己的意见，而是对所有的问题和背景进行详细的分析，让飞行员们根据自己的思考和判断作出选择。
Much as I have made every effort to remain objective, this article is the synthesis of thoughts I have formulated in my 20 years of experience in this field. At any rate, I have tried to emphasise the problems rather than highlight my own solutions to them. Other experts may not necessarily agree on certain points; this only highlights the fact that an emergency parachute is the resulting compromise of solutions to performance requirements, which frequently oppose one another. This is the source of the different theories since not everyone will agree which factors are more or less important than another.
这里，我将尽力对所描述的问题保持中立客观的态度；这篇文章总结了我这这个领域二十年的经验。无论在任何程度上，我都会着重强调问题本身，而不是突出我自己的设计。另一些专家也许没必要同意某个观点。这里主要强调的一个事实是因为备份伞是诸多性能需求妥协的产物，这些需求通常都是相互矛盾的。这（对不同性能的要求不同）就是所有不同意见来源的根本。
3．
"Reliability", in its general sense, is surely the most fundamental characteristic of an emergency parachute: it's almost useless to have a parachute if there is little chance that it will work properly. Every emergency system must be quite simple to be able to function properly all the time and, preferably, not giving the pilot the opportunity to make a mistake in its use. This may seem obvious, but in reality it's quite difficult to achieve a high degree of reliability because a parachute is often installed in a harness which was not specifically designed for it and use of an emergency parachute occurs in a complex environment with many, ever-changing, variables. A special care must be taken to consider any possible complications.
3。可靠性，勿庸置疑，这显然是备份伞最基本的一个要求：如果一个备份伞工很少作正常那么这个伞几乎是没有任何用处的。任何应急系统都必须简单可靠，在任何时候都能确保发挥作用，不会留给飞行员在使用其的时候有一丝犯错误的可能。这个问题虽然看起来很显然，但是要获得很高的可靠性是很难的，因为备份伞常常被装在一个并非为其专门设计的吊带中，并且在使用备份伞的时候时候，是在各种各样的条件下（各种各样的姿态），所以必须考虑各种各样的可能。
Murphy's Law says: "anything that can go wrong, soon or later will go wrong". This isn't a pessimist's outlook by any means; it's simply logic and is the way it is in real parachute deployments.
墨菲定律如此说道：""anything that can go wrong, soon or later will go wrong"（"任何能出错的地方早晚都会出错"译者注：感觉跟数学里面的的"小概率事件不能于不会发生"的翻版一样，呵呵）这并非是悲观主意，这只是应急备份伞在实际使用当中的一个简单逻辑。
4． I have seen many cases where the parachute was rendered completely useless solely because of small, seemingly insignificant details: release pins that were too long, hook Velcro sticking to parachute lines, deployment handles too difficult to grab in a spin, apparently minor mistakes in repacking, etc… Actually, one can say that the degree of reliability of a parachute is the balanced sum of all its characteristics. The "perfect parachute" should provide (in order of discussion):
我曾经见过许多备份伞仅仅因为微不足道的细节问题导致失效：保险销过长，尼龙搭扣粘在伞绳赏了，手柄在螺旋状态下很难抓到，备份伞折叠时候的小问题等等。。。实际上，可以说备份伞可靠性的高低依赖于它的每一个细节。一个"完美的备份伞"应该具有如下特点：
* Reasonable price 合理的价位
* Minimum weight and encumbrance 最小的重量和体积
* Ease of mounting 容易固定
* No risk of accidental deployment 不易意外的打开
* Easy extraction 易于抽出
* A pod which will not open before the right time 一个准时展开的的备份伞包皮（不能早，不能晚）
* Ease of throw 易于抛出
* Correct deployment sequence 正确的展开顺序
* Guaranteed opening 确保能够打开
* Rapid opening 快速展开
* High structural integrity 高度一体话
* Small opening shock 开伞冲击小
* Lack of oscillation 开伞后摆荡小
* Low sink-rate 下沉率小
* Steerability 操纵性好
* Geometry facilitating PLF 结构外形上易于伞员做着陆翻滚
* Ease of repack 易于重新折叠
* Ease of maintenance 维护性好
* Long life span 长寿命
* Guaranteed specifications 各项参数稳定
Let's analyse each of the key points one by one:
现在我们来分析一下这些关键点
Reasonable price: That's the natural request: 'the less it costs the happier I am", especially since it's something I have to have, but will never use (at least that's what I hope!). In reality, even price is a safety factor, because if the price is too high, more pilots will decide to do without. The bottom line is that the biggest mistake you can make is to fly without a parachute because any parachute is better than none at all.
合理的价位：显然，价格越低越好，尤其是一些这些不得不买，而有根本不会用到的（至少我希望一次也不会用到），在现实中，价格是一个安全因素，因为如果价格太高，更多的飞行员选择不带备份伞；飞行员犯的最大的错误就是不带备份伞，因为带上任何备份伞（便宜的备份伞）都比不带强。

Minimum weight and encumbrance: At first sight this doesn't seem so much important, but these attributes allow a parachute to deploy more rapidly, make it easier to throw and easier to mount on a harness such that it won't impede the pilot's movements. Also, heavier equipment contributes to fatigue and encumbrance at launch, which is certainly a significant safety consideration. If safety equipment provides minimal encumbrance there is a greater chance that a pilot will always carry it along, even if they think they'll never use it.

最小化的重量和便捷性：咋一看好像这点不是很重要，但是实现这一点会使抛备份伞更快，更容易抛出去，和更容易装在吊带上而不至于妨碍飞行员的运动。同样，重量大的备份伞系统会导致飞行员在起飞的过程中感到不便和容易疲劳，这一点很重要：如果备份伞系统很轻巧，飞行员更加愿意携带，即使他们认为这辈子都不会用到这个东西。
Ease of mounting: Many times impressive contortions are required to stow a good parachute in a good harness with acceptable results. This is quite a serious problem, which really demands standardisation of systems between parachute and harness manufacturers. First and most importantly will be to decide whether the deployment handle and the bridle are part of the parachute, or part of the paragliding harness.
易于安装：（大家）常常会看到为了把一个备份伞装到吊带里面令人印象深刻的费劲。这是一个很严重的问题，实际上对吊带生产商和备份伞生产商提出了一个标准化的要求。首要的问题就是备份伞手柄和连接带是属于吊带还是属于备份伞（由谁生产）。
No risk of accidental deployment: Unintentional deployments are too frequent, and in my opinion, it is unacceptable to have safety equipment which can cause problems during a routine flight. Deployment handles which protrude too far, Velcro, solitary deployment pins, or pins that are too short, and four-flap style containers can cause accidental deployments. The container must be designed to minimise the possibility of accidental deployment; prior to every flight the pilot must verify the parachute is securely stowed.
没有误开的可能性：误开备份伞常常发生，在我看来，没有理由让一个安全设备在日常的飞行中发生问题。手柄过于突出，尼龙搭扣，插销过短，四片式备份伞包都会导致备份伞的意外打开。备份伞的安装设计必须考虑最小的误开可能，每次起飞前飞行员都务必仔细检查，确保备份伞一切正常。
Easy extraction: It must be easy to remove the parachute from its harness-mounted container, that's obvious, but this once again poses a serious problem in compatibility between harness and parachute. The shape of the deployment handle is very important: it should be semi-rigid and easy to hook a thumb through to guarantee a secure grasp when needed. It often happens that the parachute is too difficult, or even impossible, to extract from it's container (especially for less aggressive persons) because of too much Velcro, or deployment pins which are too long. In certain cases, if the pilot's in a spin, it's not even realistic to grab the handle of many parachute systems. After having mounted a parachute on a harness, it's vital to do a hang check to verify that the deployment handle is truly easy to grab and that the parachute can be pulled from the container with minimal effort and in any variety of pilots position and circumstances. Seems obvious, but almost no one actually does it! The positioning of the parachute system in paragliding, the shape of the deployment handle and the length of its connecting strap to its pod are very important.
易于抽出：很显然，将备份伞从吊带的安装包里抽出必须是易于操作的，但是又一次在备份伞和吊带的配合兼容上对于这个要求产生了严重问题。备份伞手柄的形状是非常重要的：手柄应该是半硬的的，保证在紧急的状态下且很容易让大拇指穿过和可以牢靠的握住.而时常发生的情况是由于过多的尼龙搭扣，或者保险销过长导致备份伞很难，甚至是根本不可能从吊带里面抽出来（尤其是对于那些体力较差的飞行员）；在某些状况下，比如在螺旋当中，很多备份伞系统的备份伞手柄根本就不可能抓到；因此在（首次）安装好备份伞之后务必要做悬挂检查：将吊带吊起来，自己坐在上面模拟在各种飞行状态下是否能够轻易而迅速的抓住手柄将之抛出来；显然，没有多少人做过这个模拟。备份伞的安装位置，备份伞手柄的形状，备份伞手柄到备份伞包之间连接带的长度都非常重要。
（我们来看一下这几个备份伞安装位置）

Ventral position: often one must attach the parachute before each flight. The handle is highly visible and reachable with both hands when one is seated upright, but it blocks the view and the handle becomes almost impossible to grab during a spin when the harness has been adjusted for a partially reclined flying position.
前置是备份伞：这种备份伞通常是在每次起飞前挂上的，如果飞行员是直着坐着飞行，手柄很容易在飞行中看到和抓到；但是如果吊带调节成斜躺着的话，在螺旋当中几乎不可能看见和抓到手柄；（译者注：这里应该是指大过载的情况下，导致无法起身和抬手去抅手柄）
* Lumbar position: symmetrical, elegant and easy to manufacture, but one that is susceptible to accidental deployments. The deployment handle is not visible during flight and there are definite problems in grabbing the handle, especially during a spin. The longer length of the strap connecting handle to pod, makes a controlled throw difficult. Also, if the deployment handle detaches itself from the Velcro on the harness, it is almost impossible to grab in flight.
腰部后置：（这种方式）对称，精致，易于制造，但是很容易误开；在飞行中手柄是看不见的，而且在螺旋的时候是不可能抓到手柄的。手柄和备份伞包皮之间的连接带越长，备份伞就越难抛；而且一旦手柄从尼龙搭扣上掉下来了，在飞行中几乎是不可能抓到手柄。

* Inferior position: same problems as with the lumbar position with the added concern that the parachute is highly exposed to trauma at launch and landing which may be lead to accidental deployment at launch, especially if the pilot uses both hands to get comfortable in the harness after launch. Furthermore, the parachute in this position reduces the amount of space available to the back protection system exactly where it is needed most.
底置备份伞（臀部后面）：这种方式具有腰部后置方式同样的毛病：容易误开－在起飞的时候被地面杂物挂开，或者尤其是飞行员在起飞之后为了坐进吊带用双手撑坐带的时候；另外在这个位置放置备份伞就占去了背部保护系统的安装位置。
* Lateral position: the handle is always within reach, even during spins. Use of Velcro is practical, but does not make for a stable container mounting system: it's best to choose a container integrated, or sewn, into the harness. Some pilots think that the asymmetry in mounted weight may enhance asymmetric collapses. It is possible to make the strap connecting handle to pod very short, and if the handle is poorly positioned it may get hooked by a steering toggle in flight, causing an accidental deployment.
侧置备份伞：这种方式的安装，手柄在任何姿态下都可以抓到，即使是在螺旋状态下。使用尼龙搭扣将手柄粘在吊带上是实际的，但是不要使用外置的悬挂系统，最好还是使用跟吊带一体的安装包（缝合在吊带侧面的）。有些飞行员认为不对称的重量可能回导致非对称塌陷（单边）。侧置方式能够是手柄到备份伞包皮之间的连接带最到最短，需要主意的是，不合适的手柄安装位置回导致在拉下转弯刹车的时候碰到手柄，可能导致意外开伞。
* Dorsal position: the parachute is reasonably well protected from mishaps at launch and the deployment handle is quite visible on the shoulder, but the connecting strap needs to be quite long. The routing of the bridles is problematic for the throw if you use the correct hand to deploy and may actually block the throw if you use the hand opposite to the deployment handle (which is quite a natural reflex).
背置备份伞：次种方式的安装可以避免起飞时候的误开，而且手柄位置在肩部，很容易看到；其问题是手柄到备份伞的距离太远，需要很长的连接带。连接带的安装路线也是常常有很多问题，特别是你使用了另外一只手（不是安装的时候设计用来抛备份的手，比如设计用右手抛，现在用左手了）去抛备份伞，有可能就卡住了。
Important: do a hang check to verify that extrication of the pod from the container leaves you the necessary control for a proper throw. Too much Velcro, the wrong type of release pins, or pins too long, is able to impede or even entirely prevent correct pod extraction. Be aware that it is entirely possible to mount a good parachute on a good harness in a very dangerous way!
注意：在模拟器上做一下模拟，确保你的备份伞包确实能从吊带里面抽出来，才能保证你能完成正确抛掷的动作。过多的尼龙搭扣，错误的释放销会导致你的备份伞根本就无法从吊带里抽出来。注意！你完全有可能使用了一种隐藏着极度危险的方式将一个优秀的备份伞安装到一个优秀的吊带上！
A pod which will not open before the right time: Once the pod is extracted from the container it is fundamental it does not open until the parachute has actually been thrown. If the pod opens before this time there is a much greater chance for the parachute to hook on something causing malfunction. The pilot must be able to wait, pod in hand, for the right moment to throw.
一个不到该开的时候不会开的包皮：备份伞包皮（带着备份伞）从吊带里抽出来的时候最基本的要求就是直到抛出去之前不能打开了；如果此时包皮打开了，备份伞绳就很容易挂到其他地方导致故障发生。备份伞包皮必须允许飞行员选择合适的时机将备份伞抛出。
Ease of throw: This is a very important factor depending on the weight and encumbrance of the parachute, but above all, on harness/container geometry, and the position, orientation and shape of the deployment handle. If the strap connecting the handle to the pod is too long, or if it's attached to the pod at a single point, it becomes very difficult to control the throw and the parachute may snag the hang glider frame or, even more likely, wrap itself among the paraglider lines. Double handles, which have been relatively popular in recent years, are especially prone to tangle in paraglider lines impeding parachute deployment. Hook Velcro, found on many deployment handles, can be responsible for a variety of deployment problems and has been the cause of at least one death.
容易抛出：这一点非常重要，而且依赖于备份伞的重量和大小，吊带和备份伞容器的形状位置，手柄开口朝向和形状。如果手柄到备份伞包皮的连接带过长，或者到包皮的连接点只有一个，这样就很难控制备份伞扔出去的方向，甚至会导致缠绕在悬挂滑翔机或者伞绳上。近年来，相对开始流行的双手柄在抛备份伞的时候尤其可能导致缠绕到伞绳上面。而许多备份伞手柄上的尼龙搭扣在抛备份伞的时候会导致很多问题，并且至少是导致了一例死亡事故。 Ballistic and pneumatic systems have been used to assist deployment. The advantage of these systems is that they allow optimal positioning of the deployment handle and bring the parachute to full line extension very quickly. The disadvantages are that it is impossible to choose the direction of deployment, and system complexity is significantly greater which reduces reliability.
弹射和充气系统曾经用于辅助开伞。这种系统有利于将手柄安排到最合适的位置，并且让备份伞迅速拉直展开。但是这种系统的缺点是无法选择抛出的方向，并且系统的复杂性大大增加降低了可靠性。
Choice of correct throw direction contributes to a more rapid deployment and helps avoid a host of serious problems which may lead to malfunction - it is vital that pilots learn to follow the correct deployment procedure.
飞行员在学习正确的抛备份伞时要学到很重要的一点是：将备份伞包向一个正确的方向，这将避开许多导致备份伞失效的情况发生。
Correct deployment sequence: To reduce the possibility of malfunction during deployment of the parachute, and to reduce the risk of interference with the hang glider or paraglider, one must guarantee that the deployment sequence will be 'bridle - lines - canopy' and that the pod will not open until it has been thrown. If the pilot has not succeeded in an aggressive throw and one falls at more or less the same speed as the closed pod, it becomes indispensable that the pod will open with very little line tension.
正确的展开顺序：为了减少发生缠绕的可能性，一顶备份伞必须具有正确的展开顺序：连接带（备份伞和吊带的连接带）――伞绳――伞衣，并且备份伞包皮在备份伞被抛出之前不能打开了。如果飞行员没有能够有力的将备份伞包抛出，备份伞包皮必须在自由下落的速度下或者与之接近的速度下确保能够打开 The cumulative length of the bridle, the lines, and the parachute canopy must be less than the line lengths of the paraglider. If this is not the case, the parachute may interfere with the leading edge of the paraglider, impeding, or at least delaying, full deployment. This penalises parachutes with a larger surface area since, generally speaking, a parachute's sink-rate and stability suffer badly when the length of the parachute lines become less than the diameter of the canopy.
对滑翔伞而言：备份伞的连接带，伞绳和伞头三者加起来的总长度必须小于滑翔伞伞绳的长度，如果不是的话，滑翔伞会和备份伞发生干涉，阻碍或者推迟备份伞的打开。但是这个要求会导致（有可能导致）备份伞的伞绳长度小于备份伞伞花的直径，其代价就是备份伞的稳定性和下沉率受到损害。

For hang gliders, to keep the parachute away from the wing, the bridle must extend past the hang glider's leading edge. But paradoxically, much as it is required that the bridle is long and that longer lines improve stability and parachute sink-rate, it is necessary to have a short sum of bridle plus lines to get a fast deployment; Is a compromise necesssary?
对悬挂滑翔机而言，连接带的长度必须跨过前缘，这样的后果是增加了备份伞的稳定性和降低了下沉率。但是作为快速打开的要求而言是需要缩短连接带的长度，所以这些长度的选择是一个妥协。
Guaranteed opening: It must never be forgotten that anything attached to an emergency parachute is something that can snag. As such, the pod must never be attached to the parachute canopy, and pilot chutes must never be used regardless of configuration. For the same reason, canopy vents increase the possibility of fouling during the deployment sequence. In a real life emergency, it is shown that one falls at relatively low speed, and the pod, still closed, falls faster than the pilot. It is precisely this difference in speed that extends the emergency parachute lines facilitating its ultimate deployment from the pod. Any factor slowing the fall of the pod in this scenario leads to delayed deployment.
确保能够打开：绝对不能忘记的一点就是：任何连接在备份伞上面的东西都会是一种障碍：例如，永远不要将外包皮系在备份伞上（译者主：国内有伞友这么做，目的是为了抛了备份伞之后还能找到包皮和手柄，而且这样的备份伞据译者所知，至少有一人抛过一次，一人抛过两次，在这三次中，有一次包皮于伞绳发生了缠绕，并且被撕裂）；救生伞决不能做一些无谓的造型，同样原因，通气孔同样增加了破坏打开顺序的可能。在实际发生危险的时候，通常会看到飞行员下坠的相对刚抛出的备份伞包而言速度较慢（注意，是下坠速度），这个时候备份伞包皮还没有打开导致其比飞行员下坠的快，就这一点速度差别就会导致降低备份伞的打开时间；

Once line and canopy extension occur, and nothing has snagged, the possibility that a round parachute will not open correctly is negligible. One cannot say the same of more complex parachutes, those with vents, those that are steerable or asymmetrically vented, and especially those parachutes of the Rogallo style which are highly susceptible to even the smallest mistake in packing or interference during the deployment sequence.
一旦伞绳和伞衣拉直了之后，如果没有其他东西阻碍的话，圆形伞的打开是勿庸置疑的。但是复杂的备份伞就不一定了，尤其是那些带有通气孔的，带可操纵或者非对称通气孔的，尤其是洛佳罗式的备份伞就更加容易出问题了，所以在折叠这些备份伞的时候尤其需要小心，一点微小的错误就有可能导致开伞顺序出问题
Rapid opening: In the mountains the majority of one's flight time is spent relatively close to terrain, exactly where the possibility of tumbling and collapses are the highest. Furthermore, in case of a collapse at high elevation above the ground (without structural failure), a paraglider pilot must always focus on regaining control of his wing, avoiding use of an emergency parachute unless all else fails or little elevation remains. In real accidents one drops at relatively low speeds, often less than 10 m/s, because the broken hang glider or collapsed paraglider greatly slow the descent. Rapid deployment of an emergency parachute is indispensable especially for these low speeds.
迅速充气：在山区飞行的时候大部分飞行时间都是近地飞行，而恰恰这个位置就是容易发生塌陷的地方。另外当滑翔伞在距离里面很高的地方发生塌陷的时候，飞行员一般都是选择尽量恢复控制而避免使用备份伞，除非是所有的措施都失效了，或者距离地面太近不得不抛出备份伞。在实际的事故当中，通常都是飞行员以一个相对较低的速度下坠，通常是低于10米每秒，这是因为坏掉的三角翼或者已经塌陷的主伞大大降低了下坠速度，所以备份伞必须要在这种低速情况下有效迅速的打开。
today always speaks of 'opening speed', but in reality it is the 'vertical opening distance' which counts, i.e. the vertical distance necessaryfor the parachute to open. This opening distance largely depends on your sink-rate at time of deployment: a lower sink-rate usually requires a greater opening distance. The most difficult situation for deployment is the negative spin (no forward speed and low vertical speed), whereas, for example, a spiral dive autorotation (high speed) speeds up parachute deployment. The bottom line is that the parachute must open correctly at any speed. Note that if the parachute opening tests are made starting from 0 speed, with the pod attached, the opening distance is shown to be almost precisely a function of the opening time squared, i.e. doubling the opening time requires basically 4x the opening distance.
现在人们常说的"打开速度"实际上应该是"垂直打开距离"，表示自抛出之到备份伞打开的下降距离。这个距离在很大程度上依赖于抛备份伞时候的下降速度：较低的下沉率会导致较大的打开距离。抛备份伞最糟糕的的状况是在倒水平螺旋（没有前进速度，低的垂直下落速度）下，而高速螺旋中，由于旋转速度很高，备份伞可以很快的打开。关键是备份伞在任何速度下都要有效的打开。需要注意的是，如果备份伞打开试验是从0速度开始，并且是包着伞包皮的，那么此时的打开距离基本上就跟打开时间的平方成正比了，比如，打开时间增加一倍，下降距离就会是原来的四倍。

High structural integrity: A parachute designed specifically to withstand the opening shock associated with terminal velocity is no doubt desirable but, to reduce the opening shock to an acceptably safe level for the pilot, it is necessary to increase the opening time, which increases the vertical opening distance. This is not at all desirable for free flight application.
高度的结构一体性（结构强度）：降落伞的设计特别要考虑开伞终端速度下的冲击载荷，当然这一载荷也必须是在人体能够承受的范围之内，所以必须要增加充气这一过程的时间，这一要求增加了下坠距离，而且这一要求是同自由飞行的要求向背的。（译者注：1降低开伞冲击要求是飞机跳伞的一个很重要的要求2：终端速度是指物体在大气中自由下落时，大气阻力与重力相等后，物体速度不再增加时候的速度）
Years of accumulated experience suggest the choice of the following compromise: set structural standards for paraglider lines and hang glider hang-loops high enough to essentially exclude the pilot can separate from his paraglider or hang glider, and test emergency parachute equipment for structural integrity to roughly 150 km/h. Remember it takes considerable time and distance to reach high speed: if terminal velocity is 180 km/h (chosen value by skydivers), it takes 6.1 seconds (151 m) to reach 150 km/h in free fall, while to reach 170 km/h takes 9.1 seconds (283 m). It is wrong to say that ACPUL tests parachutes in free fall and DHV does not: for paragliders, ACPUL makes one test dropping an 80 kg weight for 5 seconds (ignoring friction, reaching a maximum of 176 km/h) while DHV drops a minimum weight of 100 kg from 85 m (providing a top velocity of 147 km/h). The ACPUL tests load the parachutes with 14% more energy, but DHV makes the test three times with the same parachute, in which process the parachute lines lose elasticity - we leave it to you to judge which test is more severe.
多年的经验积累给出了如下一些妥协：结构标准考虑了飞行员可能会和滑翔伞或者悬挂滑翔机分离造成的高速下开伞的情况，备份伞结构测试采用的最大速度为150km/h。注意达到这一速度需要相当长的时间和距离：如果终端速度为180km/h的话（这一速度由自由式跳伞员（skydiver）给出），需要6.1秒，151米的自由下落达到150km/h的速度，如果达到170km/h需要9.1秒，283米的自由下落。这些数据并不能说明ACPUL和DHV的试验方案是错误的（注：因为两者的试验方案重物阻力都比人体小），ACPUL使用80kg的配重自由下坠5秒测试一次（如果忽略阻力的话，可以达到176km/h的最大速度），而DHV采用100kg，下坠85m（提供最大速度147km/h）。ACPUL的测试冲击载荷比DHV高14％，但只测试一次，而后者使用同一顶伞测试三次，这样可以消除伞绳弹性，至于哪一种测试方法更为严格，需要您来判断。
To provide perspective, the American TSO certification for sky diving and military parachutes require the same parachute to be submitted to 60-odd deployments with a 77 kg load, frequently at 240 km/h (double the energy roughly of the European free-flight certifications). The European CEN certification for emergency parachutes has not yet been officially completed and as such I provide no comment on these new standards.
为了提供更多的参考，我们来看一下美国对于自由式跳伞（sky diving）和军用伞的技术标准认证，这一认证要求使用77kg载荷，通常在240km/h速度下，进行六十多次的开伞试验；（这一要求比欧洲的自由飞（译者注：这里的自由飞是指滑翔伞，三角翼，气球运动，非飞机跳伞）要求的冲击载荷能量大了一倍），而关于应急备份伞的欧洲标准还没有正式出台，所以在此我对这些新标准没有评论。
Small opening shock: This is a continuation of the same issue as structural integrity: reduction of opening shock is inextricably linked to an increase in opening distance. It is worth remembering that a pilot can withstand an opening shock of well over 20G since he is subjected to this force for only a very short time. Also worth remembering is that the opening shock is proportional to the velocity squared: for example, giving the same parachute, the opening shock at 150 km/h is 9 times greater than the opening shock at 50 km/h.
开伞冲击小：这个实际上是上一个话题的延续，开伞冲击是结构强度联系在一起的，而减小开伞冲击无可避免的的要增加充气时间。不过需要记住的是飞行员可以承受20G的开伞冲击，因为这个过载的时间非常短暂。同样需要注意的是，开伞冲击是跟开伞时候的速度的平方成正比的：例如，同一顶伞，在150km/h速度下开伞的冲击载荷是在50km/h速度下开伞冲击载荷的9倍。

Lack of oscillation: A high level of stability is vital since the ultimate impact force when a pilot touches down often depends more on the pilot's swinging to and from than on the actual sink-rate of the parachute. In this context one must take note that,generally speaking, high porosity fabric makes for a more stable parachute and a lower opening shock, but does this directly at the cost of sink-rate and opening distance. The best results are certainly achieved by designing a parachute specifically for the intended application. A common misconception is that classic style round parachutes are more stable and oscillate less than pull down apex ones. Stability is often influenced by seemingly insignificant factors and is always heavily influenced by the close proximity of the malfunctioning paraglider and by the exact position of the center of gravity of the pilot with respect to the emergency parachute canopy. This center of gravity position is mainly determined by the location of bridle attachment points on the harness and the bridle geometry.

开伞后摆荡小（下降稳定）：高度的稳定性是至关重要的，因为最后接地的时候，接地冲击更多的来源于摆荡所造成的冲击而不是垂直下降速度。但是需要注意的是，通常来讲，较高的伞布透气率会导致下降更加稳定，开伞冲击更小，但是这是以增大下降率和损失开伞高度作为代价的。所以最优的结果是根据设计目的来选择材料。一个常见的误解就是普通圆形伞的稳定性比下拉顶部的圆形伞好。备份伞的稳定性常常受到一些不起眼的细节影响，同时也极大的受到失效的主伞的影响，以及备份伞连接处跟伞员中心位置的关系，这一关系取决于吊带和连接带的几何形状，连接位置。
（译者注：的确如此，备份伞抛出后的稳定性收到主伞的影响非常大；第一次抛备份伞的时候，居然忘记了如何正确的收回主伞，导致将主伞弄得一团糟；第二次备份伞意外掉出时，就很轻易的将主伞收回了）

Low sink-rate: It is possible to improve (i.e. reduce) the sink-rate for a parachute of a given size by designing it with the highest possible aerodynamic drag coefficient. However, to obtain a better sink-rate for the same pilot weight on the same model parachute, the only possibility is to use a larger size parachute. A seemingly obvious choice made by many, however, a larger size requires a greater opening distance, more weight, more volume, greater encumbrance to extract from the container and accurately throw, and a higher price. A larger size of the same design has longer lines and requires a larger volume of air for inflation: at high speed the vertical opening distance required by a parachute is related to the square root of the surface area (doubling the surface area increases 1.41 times the opening distance). However, in real life deployments at very low speed, other factors, especially the parachute weight, strongly influence this formula: a reasonable estimate would be that a parachute of the same model, but twice the surface area will require almost twice the opening distance.

下沉率小：在一定的尺寸下，可以通过设计最大的空气阻力系数来降低最小下沉率。但对于同一设计的的备份伞和同样重量的伞员，只能通过增加降落伞面积来减小下沉率。但是很显然，更大的面积（同一设计而言）会导致开伞距离增加，更多的重量，更大的体积，更不便使用，影响精确的抛出，更高的价格。同一设计采用更大的面积之后，需要更长的伞绳，需要更多的空气来充气，更长的充气距离：也就是更高的开伞速度。（面积增加一倍，需要原来速度的1.41倍的开伞距离）但是在实际的使用当中，备份伞都是在很低的速度下抛出的，其他因素，尤其是备份伞的重量会大大影响这一公式，对于同样的设计而言，面积增加一倍，开伞距离同样会增加一倍。

It is difficult to visualize a sink-rate given in m/s. A good system to gain a feeling for sink-rate is to use 'equivalent jump height' instead of sink-rate. Since friction of the falling pilot can be assumed to be negligible, the kinetic energy (mv2/2) equals the potential energy (mgh): this provides us an equivalent jump height of h=v2/2G. For example, a sink-rate of 6 m/s is roughly equivalent to jumping from a wall of 1.8 m height (6 x 6/20). If one knows the equivalent jump height of a parachute model with a particular pilot weight, it is very easy to calculate the equivalent jump height with your own weight. The relationship is, for our purposes, directly proportional, i.e. double the pilot weight gives double the equivalent jump height which gives double the energy of impact. It's easy to simulate the landing impact by hanging yourself in your harness from a cord passed through the same anchor points that your parachute bridles are attached to, with your feet at the equivalent jump height corresponding to your weight, then cutting the cord. Don't do this test if you have any doubt concern at all of hurting yourself and don't place too much confidence in back protection: rigid style back protectors can allow expose your spine to an impact force of 40 G in a fall of only 30 cm - more than enough to collapse vertebrae and put you in a wheelchair for life! The greater the sink-rate the greater the risk of injury. However, the more we reduce the sink-rate the longer it takes for the parachute to open and then we must concern ourselves that the parachute may not open in time during a low elevation deployment. A lower sink-rate makes it easier to disable the paraglider to reduce its interference with the parachute; however, this procedure requires altitude and experience to be successful. It should be the responsibility of instructors to teach newcomers to our sport the correct procedures for disabling the paraglider and how to properly execute a PLF (Parachute Landing Fall), which is not only useful during a parachute landing.

很难想象有m/s表示的下沉率对伞员的影响，所以通常人们以相当于从多高的台子上跳下的感觉来描述对应的下沉率所造成的冲击，即"当量高度"这一说法。因为跳下的高度很低，所以阻力可以忽略，动能等于势能：这就提供了当量高度的计算方法：当量高度H＝下沉率的平方V^2/2G ,例如6m/s的下沉率就等于从 H＝（6×6）/ （2×10）＝1.8米高的地方跳下的冲击；所以你可以穿上吊带，在挂备份伞连接带的地方挂上一根绳子，悬挂到你算好的高度（注意是脚离开地面的高度），同样是你被备份伞挂着的姿势，然后砍断绳子，你就可获得同样开备份伞落下的感觉；但是！！不建议你做这个试验，如果你对任何伤害自己的可能都比较担心的话；也不要对你的背部保护板抱有太大的信心，一个好的背部保护板能够承受40G的冲击载荷，而这也就相当于30cm的自由下坠（译者注：去年一位伞友从小凳上跌下将脊椎摔断）――这也就足以让你在轮椅上度过余生了；更快的下沉率会导致受伤的几率增加，但是更小的下沉率又会导致开伞距离要求增加，所以这里需要做一些妥协，以保证在低高度下能够打开。较低的下沉率下，收回主伞比较容易，当然，收回主伞需要一定高度和时间；教练员有责任教授新手如何拉倒主伞并收回来和如何正确的做着陆接地翻滚。（PLF）

The controversy over sink-rate is essentially a philosophical problem: Alain Zoller - Swiss Federation test pilot - with considerable experience deploying parachutes in simulated accidents, prefers a good sink-rate, while Andy Hediger - renowned Paratech test pilot - who has performed at least 5 deployments in real accidents, prefers flying with a parachute which opens fast. To allow everyone to decide for themselves, pilots must be clearly informed what sink-rate they will get with their weight on a particular make and model of parachute, very carefully remembering that what is acceptable for a young karate champion would be totally inappropriate for an elderly pilot in average physical condition.
关于下沉率的问题上有各种各样的见解：具有丰富的模拟事故经验的瑞士协会的试伞员 Alain Zoller倾向于更小的下沉率，而著名的Paratech公司的试飞员Andy Hediger在实际故障中跑过5次备份伞，他就倾向于更快的开伞速度。所以你必须明白你的体重和对应你所选择的备份伞的下沉速度，要明白一个空手道冠军的选择并不能适用于一个普通体质的高龄飞行员。

These are the maximum sink-rates allowed by the different certification organisations. To easily compare them I have listed the equivalent jump heights for 60, 80 and 100 kg pilot loads. (converted to english values and weights by Just Fly)
这里是不同认证机构给出的所允许的最大下沉率。为了对比效果，我给出了不同体重飞行员对于这个下沉率的当量高度。（Lbs 磅， fpm 英尺/分钟）
132 lbs. 176 lbs. 220 lbs.
DHV: 1338 fpm @ 155 lbs. 6.6 ft. 8.8 ft. 11 ft.
ACPUL: 1082 fpm @ 176 lbs. 3.77 ft. 5 ft. 6.3 ft.
TSO: 1260 fmp @ 170 lbs. 5.3 ft. 7.1 ft. 8.9 ft.

The DHV and ACPUL values are specifically for parachutes intended for emergency use for free flight. The TSO values are for military parachutes and emergency parachutes for skydivers. I have added the TSO standards for comparison and because it's the certification which has been most heavily tested and is universally accepted.
DHV 和 ACPUL 的数据主要是应用于自由飞行的，而TSO主要是针对军事跳伞和自由式跳伞运动员的备份伞。这里加入TSO的对比，主要是因为TSO的测试是非常严格而且得到了广泛认可的一个认证。

At first glance it seems that DHV accepts very high sink-rates, but it is important to consider we're speaking of maximum values here: as for DHV, a very heavy pilot would purchase a larger parachute, certified for a higher weight. With the ACPUL certification, even if one is very light, he cannot purchase a smaller parachute to reduce weight and encumbrance because the smaller size cannot be certified. Sink-rate changes dramatically with pilot weight and it is not possible to have one parachute for all pilots. In this regard I have long proposed to CEN (the new European Certification Standard)

that all parachutes should have a label with a number which, when multiplied with the weight of the pilot, gives the equivalent jump height. As such, everyone would be able to choose an appropriate size parachute and be aware of the results and requirements of one's choice. The impact force at the ground heavily depends on wind speed: roughly speaking, a 20 km/h breeze would result in double the impact force as one would experience in calm conditions, and a wind speed of 40 km/h would result in a impact of 5 times larger than calm conditions almost regardless of the sink-rate of the particular model emergency parachute.
咋一看好像DHV接受更高的的下沉率，但是必须要考虑到的是我们所说的是最大值，作为DHV而言，一个体重大的飞行员会买一顶符合更大重量的更大备份伞。而对于ACPUL认证而言，即使是一个体重较小的飞行员也不会买到更小的备份伞，因为小的型号无法通过ACPUL的认证。下沉率跟体重的关系很大，不可能用同一大小的备份伞满足所有的飞行员。就此而言我一直推荐新的欧洲标准当中的标注，就是说所有的备份伞必须有个标签标出一个系数，飞行员用体重跟这个系数相乘即可得出当量高度。这样的话飞行员就可以作出自己的选择。同样风速会大大影响接地冲击载荷，大致说来是这样一个关系，20km/h的小风条件下的接地冲击2倍于无风条件下的冲击载荷；而40km/h风速下的接地冲击则是5倍于无风条件下的冲击载荷，这种关系基本跟备份伞的类型和下沉率无关。

DHV and ACPUL differ considerably also when it comes to their choice of acceptable parachute opening times: their respective tests do not resemble one another in any way and, as such, are extremely difficult to compare. However, in broad strokes, ACPUL requires an opening time of under 4 seconds in a rapid autorotation and under 6 seconds in a parachutal phase. DHV requires the parachute to open in less than 60 vertical meters when the load (simulating the pilot) and the parachute are dropped in free fall, side by side, at the same time.
DHV 与ACPUL在可接受的降落伞开伞时间这个问题上也是有显著的不同观点：他们各自的试验方式上大大不同，很难比较。大致来讲，ACPUL认可在高速自转下4秒以内打开和跳伞状态下6秒以内打开。而DHV要求在带着模拟飞行员必须在60米的垂直下落距离内打开，下抛时备份伞是同假人处于同一高度并列放下。(即伞包是已经从吊带中抽出，)
Steerability: The ability to steer a parachute away from an obstacle, or to face oneself into the wind, would be an evident advantage. For hanggliders this is not possible because the long bridle removes any possibility of use of a directional control mechanism. For paragliders it is possible to use round steerable parachutes, providing a glide of less than 1 if the paraglider is released. With the paraglider there is a huge loss in glide performances and, with sufficient altitude, it is probably possible to get oneself facing into the wind.
可操纵性：具有可操纵能力的降落伞可以使伞员避开障碍，或者能够顶风降落，这是一个显然的优点。对于三角翼来讲，这一点是不太可能能，因为骨架会顶着伞绳。对于滑翔伞飞行员来说，使用圆形可操纵备份伞，在抛掉主伞之后能够获得不大于1的滑翔比。如果带着主伞，会大大影响滑翔比，不过至少可以正对风向降落。
A Rogallo style emergency parachute is a different matter: deployment is rapid and it has a glide angle close to 3:1, but to avoid serious problems of interference between the two 'wings' it becomes necessary to cut away from the paraglider. This involves, of course, a serious risk of entanglement and a remarkable complexity in procedure, especially if one takes into account other details such as disconnection of the speedsystem. In my opinion, given the likelihood of deployment at lower elevations, the real benefits are minimal compared to the theoretical benefits and are possibly overshadowed by the system's disadvantages.
而洛佳罗式备份伞又是一个不同的话题：这种备份伞充气迅速，并且具有接近3比1的滑翔比；但是这种
备份伞需要避免很严重的两伞干涉的问题，需要(在空中）将主伞抛弃掉.这牵涉到很大的风险，包裹两伞干涉，缠绕，还有就是抛弃主伞的时候如何处理加速系统同主伞的连接。就我的意见而言，（这种系统）如果在低高度下抛备份伞，实际上能获得的好处比起理论上来讲的小多了，而且可能被系统的缺点所掩盖。
图片源于：
http://www.expandingknowledge.com/Jerome/PG/Strange/Image/RESERVE_Steerable_Rogallo_VL_1998_03_p27.jpg

Geometry facilitating PLF (Parachute Landing Fall): Certainly one of the most important issues. However this depends on the location of the attachment points of the parachute on the harness, and not on the parachute itself. Our legs are very efficient shock absorbers: a fall of only 50 cm on the back, without suitable back protection, can easily put us in a wheelchair, while such a fall landing on one's feet is absolutely insignificant. Suspend yourself with your harness, 2 meters above the ground from a variety of anchor points corresponding to possible attachment locations for your emergency parachute bridles, and imagine cutting the rope and performing a PLF from this height. The best points of attachment for the parachute bridle are the specifically intended shoulder location common on most paragliding harnesses. Use steel quick-links instead of knots or girth hitches, which can cause the webbing of the bridle to melt through under high impact loads. There are two bridle styles to attach the parachute to the harness: inverted V, and H. If the inverted V bridle is too short the pilot could have problems with his neck. Conversely, since the shoulders are not likely to be at the same height at the time of the opening shock, use of an H bridle can result in the parachute opening into a 'Mae West' malfunction. Both cases offer drawbacks, however they are extremely improbable.
几何构型上有利于着陆翻滚（PLF -Parachute Landing Fall): (译者注：PLF -Parachute Landing Fall即伞兵着陆5点接地法，伞兵由空中下降在接触地面时，以五点（脚掌、小腿外侧、大腿外侧、臂部'背部侧边肌肉）逐渐减少下降之冲力。)这个要求无疑是很重要的。这点取决于备份伞连接带在吊带上的固定点的位置，而跟备份伞本身关系不大。我们的腿是非常有效的的减震器，而我们的背部在没有良好的保护的状况下50厘米的跌落就可能造成我们终生瘫痪，而这样的高度对于腿来讲没有丝毫问题。穿好吊带，在可能装吊点的地方装上备份伞连接带，悬挂到两米高，然后想象一下切断挂绳，做一个着陆翻滚。最后你会发现最佳的连接点是在肩部，而这一方式也被广泛采用。使用钢制快挂代替连接带套接会导致在大载荷冲击下破坏连接带（所以不要采用钢制快挂）。通常采用的备份伞连接带有两种方式，一种是倒V型，一种是H型。如果倒v型的连接带太短，可能会挂住伞员的脖子，而如果使用H连接带，通常在开伞的时候两肩的位置不一样高，会导致"Mae West"失效。这两种方式都有缺点，但是这些问题发生的几率还是非常小的。
下面两图由译者添加，源自：
http://www.southernskies.net/page_info/parachute_landing_fall.html

For hang gliders, it's best to anchor the parachute bridle directly to the main harness carabiner so that during the descent under parachute, the parachute supports the weight of the glider and the pilot will have some possibility of movement. If the parachute is attached to the pilot, the opposing aerodynamic forces of parachute and glider will trap the pilot in a likely undesirable position and, as unfortunately happened to Brad Koji, the bridle or control bar can hook under the pilot's chin. Watch for harnesses with large stiffeners in the back: can prevent your back from bending to absorb shock upon landing, thus leading the possibility of crushed vertebrae.
对于三角翼飞行员而言。。。（略。。。。）

Ease of repack: Ease of repack is a fundamental characteristic of an emergency parachute as is its capacity to function even if it has not been perfectly packed. The layout must be such to preclude the possibility of significant packing errors. It is vital to provide good packing instructions with the parachute and that no one with inadequate experience shoulders the responsibility of parachute repacking. Rogallo style parachutes must in all circumstances be packed by true experts.

容易重新折叠：这是备份伞的一个基本要求，布局必须清晰，排除任何明显的折叠错误的可能。备份伞必须随附一份清晰的折叠说明，而且没有经验的人是不允许自行折叠。而且，对于洛佳罗式的备份伞必须由真正的专家折叠。

Ease of maintenance: Maintenance, and especially timely repacks, must be easy to perform and be well-explained in a comprehensive owner's manual precluding chance of error. Packing a parachute every 3 or 4 months facilitates faster deployment and provides the best way to do a safety check on the system so that one is always confident it will work when needed. When buying a parachute do not discount the possibility that lines and/or bridle may be easily replaced.

容易维护：维护性，尤其是常常重新折叠，必须容易操作；三，四个月重新折叠一次有利于备份伞更快打开。但是在购买备份伞的时候不要考虑伞绳和手柄/连接带是否容易更换。

Long life span: Parachutes are constructed of synthetic materials which, while of impressive strength, deteriorate over time. The canopy nylon is very susceptible to UV radiation: left in the sun, the canopy can lose up to half of its strength in one week and, as such, must be effectively protected. Take note that many weaves of container material allow light (and hence UV) to filter through to the parachute. Regardless, it is best to retire a parachute after 10 years, or use it only as secondary parachute.

寿命长：现代降落伞都是有合成材料制成，具有非常高的强度，但是也不可避免的随着时间流逝而降解。制作伞布的尼龙对紫外线非常敏感，如果放在在阳光直射下，伞布会在一周后损失其一半的强度（◎＃￥％￥＃％……￥※！！！！），因此应该尽量避免阳光直射，妥善保管。同时备份伞出厂十年后应该报废，或者仅仅用于第二备份伞。（译者注：说句难听的话，现在再销售或者购买98年，99年就已经出厂的二手伞作为飞行使用是不合适的，即使这样的伞句根本就没有用过一次，当然作为地面斗伞训练是没有任何问题的）

Guaranteed specifications: A parachute's specifications must be printed on the canopy to allow a pilot to verify its suitability. These specifications must be guaranteed by the reliability of the manufacturer, or better yet, by a certification system which is both serious and comprehensive of everything which, in my opinion, does not yet exist.

各项指标稳定：每一顶降落伞的各项新能指标应该像其说明书里面标注的一样，这样飞行员才能购买合适的备份伞，这必须由生产商保证其可靠性。当然由一个严肃，专业的机构来认证更好，但是在我看来，这样的机构还没有。

Personal Thinking

Having provided this review, I leave it to the individual to carefully weigh the information, and upon final evaluation, decide the best compromise for oneself.

One might think that I have written much of the above to justify certain choices I have already made. Others would think that the above reflections have naturally led me to the parachute which I have designed providing the best compromise in my opinion. Everyone can think what they will, but I wish to here explain the reasons for my personal choices.

There is a profound difference between tests performed for certification, tests performed for demonstrative purposes and real life emergency parachute deployments. In the first case one wishes to verify that the parachute falls within parameters established more or less arbitrarily by some individual or organisation. In the second case one wishes to demonstrate that the parachute works well and brings you softly to the ground. In the third case one wishes to save one's life. In my opinion, an emergency parachute is used when one's life is in the balance and, as such, must offer the greatest probability to perform properly in the scenarios which have been shown to be the most common, the most important of which is low altitude above ground.

In the owner's manual of all my parachutes I provide the formula to calculate sink-rate using your own personal body weight (of course this formula is not applicable to other parachutes): the equivalent jump height which I advise whether using a CONAR or CLASSIC model is between 1.3 and 1.7 meters with an absolute maximum of 2.1 meters.

Until now (December '99), there have been 220 confirmed deployments of my parachutes in real life accidents, and probably many others I have not been made aware of. With the exception of minor scratches, in these accidents a total of six pilots were injured:

* torn knee ligaments in a pilot who landed in a boulder slope
* broken ankle with a pilot who landed in a wind of 70 km/h (the same day five friends died at Cornizzolo - Italy, due to a huge thunderstorm)
* broken jaw when a pilot hit their face on a fence post at landing
* a broken wrist when a paragliding pilot at Feltre - Italy, was dragged back up the slope in ridge lift after the parachute was deployed
* two broken ribs in a Brazilian pilot who came down on the roof of a house
* cuts on the nose of a pilot who came in, face first, at almost 3000 m in the mountains of Owens Valley - California.

A German pilot died at Castelluccio di Norcia, in Italy, because he added a deployment handle extension with "hook" Velcro to the existing deployment handle, which blocked opening of the pod.

Of these 220 deployments, roughly half were made below 100 m AGL, and a quarter below 50 m. We encountered two cases of free fall (both of them with the Classic model): at Laragne, in France, Derek Austin broke the keel of his hang glider and unfortunately was not able to throw his parachute before reaching very high speed; when he finally did deploy his parachute, the lines separated leading to his death. Andy Hediger in Zillertal, Austria, after all lines of his prototype paraglider broke, threw his parachute at a speed which was probably much higher than the 138 km/h measured by his barograph (recording data in 4 second intervals). He landed safely after a descent of more than 2000 vertical meters with an average sink-rate of 5.5 m/s.

Derek was the president of the safety commission of the British Association: he was my friend and in a sense I feel responsible for his death. If I had chosen a different compromise, perhaps he would still be with us. But then again, what would have become of the Karl Reicheggers, Robbie Whittals, Andrea Patruccos and others who threw their parachute less than 30 meters from the ground and the parachute opened just intime to save them?

Several years ago, the British Association compiled a general accident statistics showing that when an emergency parachute functioned correctly, it saved a pilot's life in 97% of deployments. In the remaining 3% were included cases where the parachute did not deploy properly or quickly enough, and further included a solitary case where the pilot died of the speed at impact under canopy.

This proves emergency parachutes in free flight do indeed work; there is always the possibility of improvement (a 3% failure is quite high anyway) and the developmental process must continue. Nonetheless, I believe the most useful step to take involves convincing all pilots that the parachute is not an accessory, but an indispensable piece of equipment and one must learn how to use it.