微量(结冰)是元素的总和

飞机结冰的潜在本质

In the mid 1950’s, a pilot learning to fly in Eastern Washington state seldom worried about ice. 他或她只有在天气合适、阳光温暖的时候才会飞. 如果一个无知的灵魂违反了基本的教义, 搜救队将被派往丘陵或山区寻找遗体.  Instrument flying in the clouds was for the airlines and even in that venue the results in winter were occasionally tragic. 四航向无线电范围, 叫做阿德科克范围, 仍然是北美大部分地区越野航行的中流砥柱. 美国正在慢慢地安装VOR测距仪, but the British were plotting to make the World-wide standard a convoluted system called Decca. 这在国际民航组织(ICAO)引起了足够的愤怒，以至于CAA(上世纪50年代还记得)?)并不急于加快安装速度. 的 tried-and-true NDB was the primary approach facility to the majority of the nation’s airports unless the city was large enough to warrant an ILS.

In 1956 the former Army Air Base at Walla Walla was a rather busy general aviation (GA) airport.  在那里 were many pilots; yet I knew of only two that possessed an instrument rating. 它们都不是当前的, 因为维持货币的唯一方法是乘坐一架在云端飞行的飞机. Currency was expensive and they weren’t going to fly IFR anyway as the majority of aircraft didn’t have the electronics, 对抗冰的工具或方法. 从工厂生产出来的带有加热皮托管的新飞机是件大事, 乐器六装是几年后的事了.

It was a cold, grey, overcast day, the ceiling about 400 feet with a light drizzle falling. 那是二月初的一个星期六.  I was working at the airport after school and weekends sweeping out one of the hangers that always seemed to fill with dust from the local wheat fields every time the large doors were opened. For the last hour, the only sound I heard was that of the broom scratching across the concrete.

周六只有两架飞机飞往瓦拉瓦拉, 几个小时后才到期. 然而,, far off, I heard the sound of an approaching light aircraft engine turning at very high RPM. 我从衣架里走出来，朝南边某处有声音的地方望去. 在那里, 紧紧抓住云层的底部, low over the buildings was a Piper Tri-Pacer on a tight base turn to the end of the runway 20, 它的引擎全速运转. 飞行员与跑道保持一致，在最后一刻关掉了引擎, 飞机像石头一样下降了最后6英尺, 轮胎撞在混凝土上, here and there shards of ice knocked loose by the abrupt landing fell from the airframe. 的 Tri-Pacer slowed, then taxied off the runway toward the FBO, pulling up to a stop where I stood. 螺旋桨刚停，驾驶舱的门就砰的一声打开了, 飞行员跳出飞机, running past me onto the wet grass lawn and then behind our little office shack that adjoined the hanger. 在那里，他上了厕所，他的背随着呼吸而起伏.

Margret, our office manager, took dim view of what was now going on outside her office window. 她怒气冲冲地从侧门冲出去，朝飞行员大喊大叫. 他转向她, 他脸色苍白，浑身发抖, 揭露可怕经历的后果. 玛格丽特一反常态地表示同情, 带他进了办公室，喝了杯咖啡，抽了支烟.  的 Tri-Pacer was covered with about 1/4 to 3/4” of clear and mixed ice on every leading edge. 在翅膀上，冰回去了一个很好的8“在顶部和3”在底部. 的 leading wing struts were not visible beneath the heavy mixed ice that completely enclosed them. 我以前从未见过飞机结冰，敬畏地看着.  大型螺旋桨上覆盖着厚厚的透明冰. I was able to pull off a complete ice mold of the spinner and I took it into the office.

看到我手里的冰, they paused their conversation for a moment and then the pilot lowered his head and spoke. “我在欧洲上空执行了28次飞行任务，我想我已经结束了. 完成.他停顿了一下，然后又说话了. “西海岸 [1] 飞到博伊西去?”

在离开办公室之前, 飞行员讲述了他是如何从博伊西到三城出差的. 博伊西的天气只有零星的云朵, but after he passed Nampa and closer to the Blue Mountains the clouds began to close up and the ceiling lowered with intermittent patches of dry 雪 falling. He could still see the ground and the mountain tops ahead, so he pressed on for 拉格兰德. 在那里，他发现他再也看不见山顶了, 因为他们被低云或潮湿的雪遮住了. 拉格兰德, OR was below him yet he chose to climb up into the clouds to an altitude higher than the mountain tops and continue on to Pasco. 如果我没记错的话, his airplane had an externally mounted venturi that drove the artificial horizon and directional gyro. 他的甚高频收音机是一个“毒品监督者”, the ADF a Mitchell “Airboy”; both considered relics even 10 years later. Without a heated pitot he climbed into the clouds and into the freezing precipitation that was plainly in view ahead and around him. 在某种程度上, 他设法使飞机在飞越蓝山的山口上空飞行, but on the upslope side he started icing up so bad he could no longer keep the wings level or hold altitude. 幸运的是, just east of Pendleton he found a hole and dove down leveling below the thickest clouds around five hundred feet AGL,沿着一条两车道的高速公路向北和向西行驶. 然而,, 这儿那儿下着小雨和毛毛雨, and his airplane skin was very cold from flight in the higher altitudes causing the moisture to freeze to the airframe. 如果这还不够的话, 几英里后, 小雨和毛毛雨变成了持续的冻雨和毛毛雨. 现在他的结冰速度更快了，每个暴露的边缘都覆盖上了透明的冰. 每次他都试图转向地势较低、空气较暖的西面, 乌云挡住了他的去路. 他继续摸索着去瓦拉瓦拉机场. During the last 20 minutes of flight the Tri-Pacers engine was at full power; the plane often shuddering on the edge of a stall as he approached to land. 

He left the airplane there until late March when a salesman arrived to fly it to a new owner.

在1956年，这是一场灾难的公式. 一个有使命的商人. 军事训练，但肯定不是目前的国际无线电飞行. 即使在当时标准不严格的情况下，飞机也配备了最低限度的IFR飞行装备. 的 known weather forecast that day for icing and low ceilings from Stampede pass to 拉格兰德. 即使是我，一个还没有独立飞行的新手，也知道这一点. Almost every moderate sized airport in the Northwest had a Flight Service Station or the Weather Bureau based on or close to the field and a rather good weather report with forecasts and graphic charts were very available along with full explanations. 然而,他走.

现在问问你自己. 60多年来发生了什么变化? 什么没有?

除非完全一无所知, every pilot has read the usual t雨ing materials about icing and how it affects an airplane. 也许他们经历了一些很快就消失的痕迹. 这件事只会成为喝酒时谈论的话题，仅此而已. 的 problem is that most GA pilots have yet to find out just how quickly and completely an airplane can be overwhelmed by icing. 机身结冰是潜伏的. 你可能会注意到前缘或挡风玻璃周围有痕迹, 你觉得没什么好担心的. 你继续, until in a blink of an eye you are packing it on to the point the deicing and anti-ice systems are close to being overwhelmed. 

冰有很多种解释，美国国家海洋和大气管理局将其定义为四种类型. You know of them; Clear, 霜, mixed and frost. 事实上, each type of ice (they say) is formed from specific types of clouds associated with a front or condition. 然而,, 当地的地理布局, 气团类型, 配上合适的加湿器往往会产生较大的水分, 更为持久, 以及微妙而持续的危险变化. 一旦冰附着在机身上，就很难移除. 让十大网赌网站大全来看看北美的一些危险地区.

的级联

这条山脉始于加拿大，向南延伸到北加州. 的y are considered without parallel for creating some of the most intense icing conditions in North America. Cool, moisture laden air is quickly lifted up the mountain sides from six to fourteen thousand feet. 平均风速为500mb (18,000’) is seldom less than 50 knots out of two hundred and twenty degrees (220°) from October to April. 低至14,000’ the prevailing winds can obtain speeds greater than 120 knots with frontal passages. 集中的太平洋湿气会迅速上升并冷却, being thrust like a fast-flowing river tumbling over huge boulders that impede the flow. 的 动荡 in the moisture can harbor pockets of differing types or intensity levels of ice. 建造速度比在阿勒甘尼山脉发现的还要快, 甚至是落基山脉上最恶劣的吸积物. 

Icing conditions on the west side of the Cascades are commonly at altitudes from 4000’ up to 22,0000’. On the east side of the mountains the freezing level and possibility for icing is from the ground up. If you are in route from east to west and start picking up icing as far east as Moses Lake or the Tri-Cities expect moderate or greater (severe) levels of mixed 霜 past Ellensburg or Wenatchee and on the descent into the Seattle area.

级联通过

In the winter the cold Canadian Polar and Plains air masses will sometimes settle in over eastern Washington and Oregon with the resultant temperatures to be much colder on the east side of the state. This polar high builds and creates a steep pressure gradient from east to west often producing very cold VFR conditions in central Washington. Because of the lower pressure on the westside the colder high-pressure air starts out-flowing down any available pathway to fill the lower pressure western Washington and Oregon.

多年来, the only way to fly from one side of Washington or Oregon to the opposite was via a few passes marked on an aeronautical chart. 以500 '或1000 ' AGL飞行, 在山脊间蜿蜒盘旋，停留在云层之下, 飞行员通过Stampede或Stevens山口或哥伦比亚河峡谷穿越. 许多飞行员，包括我自己，都做到了安全. 然而，这些路线总是存在问题. Just when you were about to clear the mountains there was a bend in the path and here you would find a wall of dense fog, 雨, 或严重结冰的情况. Attempting to turn around in the narrow confines of the Gorge often resulted in disaster.

海岸山脉

奥运会, the Siskiyou’s and California Klamath are a coastal range of mountains that are the first to feel the western steering winds that come charging off of the Pacific Ocean. 在这里，充满水分的空气首先被提升并冷却.  If it is 雨ing at 4000’ and about 2°C on the approach to Astoria or Hoquiam expect up to moderate mixed ice lurking in the clouds above 5000’ MSL if you head east. 从沿海机场飞往尤金的航班, 梅德福, Klamath Falls or Northern California can produce soul searching moments with fighting icing crossing over these ranges. 这里的冰有一个更大的湿度水平和沉重的混合冰应该是可以预料的.

的Alleghanies

作家欧内斯特·K. 江恩[2] 写了一个晚上在阿勒加尼山脉的DC-3型飞机上与冰搏斗的故事. 在他早期的一本书中曾描述过一场类似的冰战[3] of ice’s effects upon a lone mail plane and pilot as they challenged the weather Gods to complete their route.

Across that range to coastal New England flying on a winter’s night even into mid-May you’ll find thunder 雪 and aggressive 霜 greeting you as you descend from the flight levels. 事实上, 飞越17度以下的阿勒加尼和波科诺山脉,000 '可以呈现清楚, 霜, 在短短250英里的路段内混合了冰和少量的冻雨. 的 northern part of the range is affected by Lake Effect Snow that can cause airport delays that mount into days. Ice accumulation can be slow and stealthy or sudden as super cooled water droplets slam into your plane, 听起来像是霰弹枪射出来的铅弹. Without fail it will build to the point of overwhelming GA aircraft if flight is sustained too long in the freezing air. 的 AOPA航空安全协会 (ASI)最近制作了一段很好的视频，记录了两起与GA结冰有关的事故, 在这片山脉上两天内发生. 所有飞行员都应该看那个视频.

五大湖效应

Winters in the region of states and provinces that border the Great Lakes are known for sudden and severe ice and 雪storms. 的 lakes themselves do not “moderate” or warm the temperature as the Pacific Ocean or Puget Sound might affect the Seattle area. 而不是, the Great Lakes add a base line of cold moisture to the colder Canadian and Polar air masses that sweep down across the Plains from the north. This then mixes with advancing fronts from the west and is often compounded when warmer Gulf air feeds in over lower Illinois, 爱荷华州, 印第安那州和俄亥俄州. 在这些锋面的穿越过程中，雾凇和混合冰会迅速形成. 如果有雷暴，预计也会有清晰的冰. Heavy 雪 fall in the form of large flakes can obliterate forward visibility to zero in a heartbeat leaving one to depend upon their instrument flying skills. If you’re lucky the worst you’ll experience is being stuck for days when the airport can’t keep the runways open, i.e.纽约州的布法罗和奥尔巴尼.  在最近一段时间, 两个地区航空公司, 一个驾驶ATR, 另一辆Dash 8因结冰而坠毁, 天气还在继续夺走生命, 特别是通用飞机.

落基山脉

This massive backbone range of the American continent faces the prevailing westerlies that sweep off of the Pacific Ocean from Canada south to the warmer climes of Southern California and Mexico. 然而, this range is actually the second or third range of mountains that have been kissed by ocean washed air. 的 leading edge of the air mass crossing the range will develop upslope conditions similar to that across the mountains closer to the Pacific, 不过谢天谢地，除非有雷雨, 冰的强度通常较低，因为水滴的水分较少. 大风, 动荡, 雪, and very limited visibility against a white background trying to identify a runway are common problems on approach. Our old nemesis Rime ice will show up at the lower altitudes or around the temp line of an inversion.

今天, we have more digital and visual weather products at our eyes and fingertips than at any time in aviation. From applications on mobile devices to digital weather reports through GPS in the cockpit, 飞行员可以获得大量的信息. 然而, while parsing through the pages of information it can be easy to gloss over important weather forecasts that could give clue to icing hazards. We as pilots should maintain a better understanding of the unique regional weather patterns that can lead to aircraft icing, 相关的危害, and develop skills to actively manage the constantly changing situation we may find while flying in the winter months.

By 迈克·奥斯瓦尔德 - cfi, cfii, mei, atp

[1] 西海岸航空公司，早期的太平洋西北航空公司，后来被休斯航空公司合并.

[2] “命运是猎人”，E. K. 江恩

[3] 《十大网赌网站大全》，E.K. 江恩