Tree well immersion (SIS) and deep powder snow suffocation survival¶

A tree well (or Snow Immersion Suffocation / SIS hazard) is a hidden, unconsolidated void of loose snow, low-hanging branches, and air surrounding the trunk of a conifer tree after heavy snowfall. When a skier or snowboarder catches an edge near an evergreen tree and tumbles headfirst into this hidden pit, the surrounding curtain of dry powder snow collapses inward like quicksand while their skis or snowboard wedge into the branches above, trapping them upside down in total darkness. According to the Northwest Avalanche Center (NWAC) and the National Ski Areas Association (NSAA) in the United States and Canada, non-avalanche Snow Immersion Suffocation accounts for roughly 20 to 25 percent of all in-bounds winter sports fatalities during deep powder seasons, and in survival experiments, 90 percent of volunteers placed into a tree well could not rescue themselves without a partner standing right outside the tree.

This guide walks skiers, snowboarders, snowshoers, and backcountry riders through what to do in the first 5 seconds if you fall into a tree well or deep powder pocket, why thrashing causes immediate snow compaction and suffocation, how partners must tunnel in horizontally from the downhill side rather than stepping on top of the hole, and how to prevent tree well traps on powder days.

现在就这样做¶

1. If you are falling toward a tree well: let go of your poles and grab the tree trunk or branches immediately. Never keep your hands inside ski pole wrist straps when riding near trees. As you fall, reach out with both hands to hug the solid wooden tree trunk or thick upper branches to stop your head and chest from dropping inverted into the void below.
2. If you land upside down in snow: DO NOT thrash, kick, or wiggle your legs. In loose, unconsolidated powder snow, struggling acts exactly like a mechanical cement vibrator: every kick knocks hundreds of kilograms of snow off the boughs above and packs it tighter around your chest and face, sinking you deeper. Freeze your legs immediately.
3. Create a breathing air pocket in front of your mouth and nose first. Before the snow settles, cross one forearm or cup your hands in front of your face to push a small 10- to 15-centimeter (4- to 6-inch) hollow space around your mouth and nose, and tuck your chin or pull your neck gaiter/collar up to keep loose powder from falling into your airway when you inhale.
4. Stay calm, breathe slowly, and blow your whistle (if near your mouth). Panic hyperventilation rapidly consumes your small oxygen pocket and melts snow around your face with warm breath, which refreezes into an airtight ice glaze ("ice mask"). If you can reach the tree trunk with one hand, hold onto it so you do not slide deeper, and wait for your partner.
5. If you are the partner outside: NEVER step on the rim of the hole or pull the victim straight up by their boots/skis. Stepping onto the top edge of the tree well collapses a ton of snow directly onto your friend's head, and yanking upward on wedged skis or a snowboard only drives their head deeper into the pit.
6. Call Ski Patrol or emergency services immediately and dig horizontally from the side or downhill toward their head. Shout for nearby riders to help, call the resort Ski Patrol emergency number (or call your local emergency number: 911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom; see our 紧急号码 directory), locate the victim's head beneath the boots, and tunnel inward from the side/downhill to clear an airway around their face before unclipping their bindings.

Immediate survival and partner rescue decision flow¶

Whether you are the rider falling into a tree well or the partner who just saw your friend vanish under the boughs, follow this sequence immediately.

flowchart TD
    A["Rider Falls Near Conifer Tree or Deep Powder Pocket"] --> B{"Which Role Are You In Right Now?"}
    B -->|"I Am the Rider Falling Into the Tree Well"| C["Drop Ski Poles Immediately and Grab Tree Trunk or Heavy Branches"]
    C --> D["Stop All Leg Thrashing and Kicking to Prevent Snow Funnel Collapse"]
    D --> E["Cup Hands or Forearm Over Mouth & Nose to Carve a Breathing Pocket"]
    E --> F["Hold Onto Trunk if Reachable, Breathe Slowly, and Wait for Partner Excavation"]
    B -->|"I Am the Partner Outside Who Saw Rider Disappear"| G["Keep Strict Visual Fix on Exact Tree (Mark With Upright Skis or Pole Outside Rim)"]
    G --> H["Call Resort Ski Patrol Emergency Number / 911 / 112 and Yell for Nearby Riders"]
    H --> I["DO NOT Step on Top Lip of Hole and DO NOT Pull Up on Victim's Skis or Snowboard"]
    I --> J["Probe Gently With Hand Along Trunk to Locate Victim's Head and Chest Depth"]
    J --> K["Tunnel Inward Horizontally From the Downhill Side Directly to Victim's Face"]
    K --> L["Clear Snow From Mouth and Nose First, Then Release Bindings and Extract"]

How a tree well forms and why conifers look safe from above¶

Many skiers and snowboarders assume that if there is 2 meters (6.5 feet) of fresh snow on the open ski run, the snow stays flat right up to the trunk of every pine, fir, spruce, or hemlock tree. In reality, low-hanging evergreen branches act like a giant umbrella:

1. The branch umbrella: As meters of snow fall over the winter, the wide, downward-sloping lower branches of fir, spruce, hemlock, and cedar trees catch the falling snow and prevent it from reaching the ground around the base of the trunk.
2. The hidden 2-to-3-meter (6-to-10-foot) void: Directly beneath the bottom branches sits a deep, conical pit of air, tangled dead branches, and loose, uncompacted feathers of dry snow extending all the way down to the bare forest dirt or rocks, even when the surrounding snowpack is 3 meters (10 feet) deep.
3. The visual illusion: From 5 meters (16 feet) uphill, the snow-covered outer tips of the tree branches blend smoothly into the smooth powder slope. A rider carving a turn too close to the outer branch skirt ("skirting the tree") breaks through the thin crust of branch tips and drops straight into the hidden vertical shaft headfirst.

Step-by-step survival protocol if YOU fall into a tree well¶

如果您失去控制或抓住边缘并感觉自己头朝下倒在针叶树的树枝下，那么您在雪落下前3到5秒的行动将决定您的生存。

第 1 步：努力保持直立或在树干上阻止滑行¶

• 切勿在树上佩戴滑雪杖腕带：当您跌入树井时，如果您的双手被套在滑雪杖腕带内，滑雪杖就会卡在树枝上，并将您的手臂向后压在头上，这样您就无法伸手去清除积雪。当滑雪林间空地或越野粉雪时，请务必握住滑雪杖握把不要将手穿过手腕环。
• 拥抱树干或粗大的内部树枝：当您冲过外部树枝时，用双臂猛冲向实木树干或粗大的内部树枝，并将您的手臂或腿包裹在它们上，就像攀爬考拉一样。即使你的滑雪板掉落在你下方，将你的头和肩膀挂在坑上方的树枝上也可以挽救你的生命。
• 尝试仰卧或侧卧（翻身和翻滚）：如果您在远离树的深空粉雪中越过车把，收起下巴并翻身到侧卧或仰卧，这样你的脸就指向天空，而不是面朝下埋没。

第 2 步：停止所有踢腿并创造呼吸空间¶

如果您已经倒立在树井内并且雪在您周围倾泻而下：

1. 立即冻结你的双腿：人类的每一种本能都在向你尖叫，要求你踢腿并尝试向上游。 完全抵制这种冲动。 因为您的滑雪板或滑雪板长 150 至 185 厘米（5 至 6 英尺），并且被锁在您上方的坚硬树枝内，所以踢腿无法让您向上移动，它只会摇动树冠，并将数百公斤的松散雪紧紧包裹在您的头部和胸腔周围。
2. 将手臂锁在脸上（“拳师卫士”）：将一只手或双手立即放在脸上。扫一下嘴和鼻子周围的空腔，然后将前臂或双手握在嘴前几厘米处，这样沉降的雪就会停在您的手臂上，而不是平压在您的嘴唇和鼻孔上。
3. 吸入之前吐出嘴里的雪：如果在翻滚过程中雪进入了您的嘴，请将其吐出或用戴手套的手指将其扫出之前深吸一口气，以免将粉末吸入气管。
4. 随着雪的沉降，扩张你的胸部：当松散的雪在你的躯干周围沉降时，深呼吸，并在前 10 秒内稍微向外保持肘部；这会在您的胸腔周围留下一个重要的 2 厘米（1 英寸）扩张间隙，以便您在雪停止移动后仍然可以呼吸。

第三步：如果你完全孤独，你还能自我解脱吗？¶

在树井研究员 Paul Baugher（西北雪崩中心）进行的具有里程碑意义的现场测试中，90% 被放入真实树井中的测试对象无法自行逃脱。对于那 10% 设法自救的人，或者如果你打破了粉雪滑雪的第一条规则并独自骑进树林，这是唯一有效的技术：

• 仅以缓慢、从容、毫米级的速度移动：切勿猛拉或猛击。
• 将一只手固定在坚固的树干或粗根/树枝上：使用树干本身作为唯一的坚固梯级。
• 不要尝试推挤松散的雪墙：不要尝试爬上雪，而是看看您是否可以沿着自己的腿慢慢向上弹出滑雪板固定脚跟或解开滑雪板脚踝带，仅如果您的上半身已经牢牢地楔在树干上，那么松开双脚不会导致您的身体从无底轴滑下 1 米（3 英尺）深。
• 检查是否可以沿着光秃秃的树干进一步向下或向侧面蠕动：在陡峭的斜坡上，树井的下坡侧通常比上坡侧的树枝和雪壁更薄。有时，被困的骑手可以将自己拉到树干光秃秃的树皮上，然后从侧面向下穿过树枝的下坡裙边，而不是向上走。

搭档救援：如何将人从树上挖出来而不杀死他们¶

超过 80% 的树井受害者死亡仅仅是因为他们的伴侣一直滑雪到缆车底部，在缆车线上等了 15 分钟，想知道“戴夫在哪里？”*，然后乘坐缆车回来开始寻找，此时 30 分钟过去了，受害者已经窒息而死。

当您在与伴侣的视觉和声音接触范围内骑行并看到他们跌入树井（或看到针叶树下伸出一个滑雪板尖端、滑雪板底座或手套）时，您有不到 15 分钟的时间让空气接触到他们的脸。

CRITICAL PARTNER EXCAVATION RULES FOR A TREE WELL:
1. NEVER step onto the top rim of the snow cone around the tree (collapses snow onto the victim's face).
2. NEVER grab the victim's boots, skis, or snowboard and yank upward (drives their head deeper and breaks legs/spine).
3. ALWAYS approach from the DOWNHILL or SIDE of the tree and tunnel INWARD HORIZONTALLY straight to the victim's head.

分步合作伙伴挖掘协议¶

1. 标记树并立即调用备份：
   • 将您自己的滑雪板或滑雪杖直立在树上 3 米（10 英尺）处的开阔雪地上，以便接近的滑雪巡逻队或其他骑手可以立即准确地找到那棵树（在拥有 500 棵相同冷杉树的茂密森林中，将视线从树上移开 10 秒钟可能会让您失去位置）。
   • 大声喊*“救命。这里的树上有滑雪者。”*以标记正在奔跑的路过的骑手。
   • 让第二个人（或在移动时使用免提）拨打度假村的滑雪巡逻紧急直拨电话（在骑行前将其编程到您的手机中；它打印在每张纸质路线图和电梯塔上）或拨打 911 / 112 / 999 并提供准确的路线名称和电梯塔号码。
2. 稳定受害者的脚，使其不会滑得更深：
   • 如果你看到受害者的靴子、滑雪板或滑雪板缠在上面的树枝上，不要把它们拉起来，并且不要解开绑带，如果这些被钩住的滑雪板是唯一阻止他们的身体再跌入坑底一米的东西。
   • 相反，如果有第二名救援人员在场，请让他们轻轻握住或将受害者的靴子/腿固定到位，这样当您挖掘到他们的头部时，受害者就不会滑得更深。
3. 组装雪崩铲并从山下一侧挖隧道：
   • 查看受害者腿部的角度，准确估计他们的头部和胸部靠在树干上的位置（通常距离靴子下方 1 至 1.5 米/3 至 5 英尺）。
   • 绕到树井的下坡侧（或下侧），完全远离上雪缘。
   • 使用可折叠的铝制雪崩铲（如果没有铲子，则使用您的手/滑雪板）在受害者头部的高度穿过较低的树枝和雪墙，直接向内切出一个水平门口，将雪从山上铲离树，这样雪就无法滑回去。
4. 首先清理嘴和鼻子周围的气道：
   • 当你戴着手套的手接触到受害者的头盔、夹克或肩膀时，停止在他们的头部附近使用金属铲刀片，这样你就不会击中他们的脸。
   • 用手扫去他们嘴、鼻子和胸部的积雪，拉下积雪的护颈或围巾，并从他们嘴里挖出雪塞。
   • 立即检查他们是否有意识和呼吸：
     • 如果他们有意识并且有呼吸：保持他们的呼吸道畅通，安抚他们，加宽他们躯干周围的水平沟槽，以便他们的胸部可以自由扩张，然后然后松开他们上方的滑雪固定器或滑雪板带，这样你就可以将他们轻轻地从侧通道滑出。
     • 如果他们反应迟钝且没有呼吸（或只是喘气）：立即将他们救到压平的平台上，同时保护他们的颈部，打开气道，进行5次初步人工呼吸（因为树井心脏骤停是由缺氧/窒息引起的，如果您受过训练，人工呼吸与胸部按压相结合至关重要；如果您无法进行人工呼吸，请开始连续人工呼吸） 徒手心肺复苏 立即按每分钟 100 至 120 次按压）并继续，直到滑雪巡逻队带着氧气和 AED 到达。

如何预防树井和深雪浸泡悲剧¶

通过遵循国家滑雪区协会 (deepsnowsafety.org) 和 MountainSafety.info 认可的五项不可协商的粉雪日规则，每一起树井事故都是可以预防的：

• 1.始终让您的伴侣处于直接视线范围内（不仅仅是“在电梯底部见面”）：如果您在跑步顶部分开并十分钟后在缆车上见面，“与朋友”一起骑行的好处为零。在树林里或在深粉雪的日子里，以短的蛙跳式骑行让您的伴侣保持在直接视线范围内（或每 15 秒持续语音呼叫和响应），直到你们都离开树林。
• 2.在进入任何林间空地或越野滑雪道之前，请将手从滑雪杖腕带上拿开：滑雪杖带将您的滑雪杖变成锚，将您的手臂固定在头顶上方的树上，并使拇指/肩膀在树枝上脱臼。当你失去平衡时，立即松开你的杆子。
• 3.佩戴响亮的无豌豆求生哨子，夹在下巴旁边：将 120 分贝的无豌豆塑料哨子（例如 Fox 40）用胶带或夹在夹克拉链头或背包胸带上，距离您的嘴仅 10 厘米（4 英寸），这样即使双臂抵在胸前，您也可以用牙齿够到哨子。
• 4.携带雪崩收发器（信标）、可折叠金属铲和探测器，即使是在深粉雪天也要携带雪崩收发器：许多滑雪者在度假村边界内滑雪时将雪崩信标和铲子留在车内。在任何有超过 30 厘米（12+ 英寸）新雪的日子或在滑雪胜地林间空地滑雪时，请在发送模式下佩戴有源 3 天线数字雪崩收发器 (457 kHz) 并携带带有金属铲的背包。拥有收发器和铲子的合作伙伴可以在 3 分钟内精确定位并挖掘完全埋在树下的骑手，而不是花 20 分钟猜测他们落在哪棵树下。
• 5.与针叶树保持距离，切勿在树枝滴水线下转弯：留在树木之间的开放白色车道上，而不是拥抱树干，控制速度，以便在撞到障碍物之前停下来，并注意从雪中伸出的 1 米（3 英尺）小“婴儿”常绿树顶，那个微小的绿色树顶实际上是一棵 6 米（20 英尺）高的树的树冠，其中有一个巨大的树隐藏在雪面下方。对于相关的冬季山区紧急情况，请阅读我们的 滑雪、单板滑雪和斜坡事故, 雪崩, 和 荒野低温和寒冷 指南。

常见问题¶

来源已检查¶

• Northwest Avalanche Center (NWAC, United States) & Paul Baugher (Crystal Mountain Ski Patrol Director): Tree Well and Deep Snow Safety (deepsnowsafety.org), Empirical Tree Well Immersion Survival Research and Partner Excavation Protocols.
• National Ski Areas Association (NSAA, United States) and Canada West Ski Areas Association (CWSAA, Canada): Deep Snow Safety and Snow Immersion Suffocation (SIS) Prevention Guidelines.
• International Commission for Alpine Rescue (ICAR / CISA-IKAR, International / Switzerland) and Wilderness Medical Society (WMS, United States): Clinical Practice Guidelines for Prevention and Management of Avalanche and Non-Avalanche Snow Burial Victims.
• Avalanche Canada and Canadian Ski Patrol (Canada): Tree Wells, Deep Powder Immersion, and Asphyxial Burial Resuscitation Standards.
• European Resuscitation Council (ERC, European Union) and American Heart Association (AHA, United States): Special Circumstances of Resuscitation, Accidental Hypothermia and Asphyxial Arrest Ventilation Protocols.

相关指南¶

• 滑雪、单板滑雪和斜坡事故
• 雪崩
• 荒野低温和寒冷
• 徒手心肺复苏