第一次尝试着翻译Quora上的文章，还选了一篇自己一点都不熟悉的题材，估计很多专业用语用的不准确，还希望各位看观能指点指点，给我留个言~
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题目：What would happen if a plane flies too high?
作者： Tom Farrier, Retired USAF command pilot; former Director of Safety, Air Transport Association
我的翻译：
People have done this, and they have died doing it. For example, the crew of Pinnacle Airlines 3701, October 2004 (Page on ntsb.gov), was taking their aircraft from one airport to another without passengers -- a so-called "re-positioning" flight. They were supposed to fly at 33,000 feet, but instead requested and climbed to 41,000 feet, which was the maximum altitude at which the aircraft was supposed to be able to be flown. Both engines failed, the crew couldn't get them restarted, and the aircraft crashed and was destroyed.
如果一架飞机飞的太高会发生什么？
曾经有人试着飞的更高，然而他们都死了。例如，Pinnacle Airlines 3701的机组人员（参见2004.10Page on ntsb.gov），驾驶着他们的飞机到另一个无乘客飞机---被称作“重新定位”飞行。他们本该飞到33000英尺，但是被要求飞到41000英尺，这是飞机所能飞到的最高海拔。所有的引擎都熄火了，全体人员无法再重新启动，最终飞机坠毁了。
The National Transportation Safety Board determined that the probable causes of this accident were:
国家运输安全委员会断定照成这次事故的原因是：
(1) the pilots’unprofessional behavior, deviation from standard operating procedures, and poor airmanship, which resulted in an in-flight emergency from which they were unable to recover, in part because of the pilots’inadequate training;
飞行员的非专业行为，偏离了标准操作程序，并且欠佳的飞行术，导致飞行中的紧急情况他们无法重新应对，另一部分原因是飞行员的培训不足。
(2)the pilots’failure to prepare for an emergency landing in a timely manner, including communicating with air traffic controllers immediately after the emergency about the loss of both engines and the availability of landing sites;
飞行员未能及时准备紧急降落，包括紧急情况发生后立即和空中管制员沟通引擎失效和可能的着陆点。
(3) andthe pilots’improper management of the double engine failure checklist, which allowed the engine cores to stop rotating and resulted in the core lock engine condition.
另外飞行员不恰当的操纵双引擎故障检测表，允许引擎内核停止旋转，导致内核锁定引擎的状态。
Contributing to this accident were:
这次事故的照成是：
(1)the core lock engine condition, which prevented at least one engine from being restarted, and
内核锁定引擎的状态会阻止至少一个引擎重新发动，
(2)the airplane flight manuals that did not communicate to pilots the importance of maintaining a minimum airspeed to keep the engine cores rotating.
同时飞机飞行指南没有给飞行员传达维持飞机最小空速来保持引擎内核运行的重要性。
Accidents also happen when the "density altitude" - a combination of the temperature and atmospheric pressure at a given location - is too high. At high altitude on a hot day, some types of aircraft simply can't climb. They might get off the ground after attempting a takeoff, but then they can't gain altitude and they crash because they run out of room in front of them or because they try to turn back to the airport and stall the aircraft in doing so. An example of this scenario is described in WPR12LA283.
事故也发生在密度高度，在固定的位置上温度和气压的结合--飞行太难了。炎热一天的高海拔，某些类型飞机无法上升，他们可能在试图起飞后离开地面，但是他们不能上升海拔，他们坠毁是因为他们起飞的空间不足或者因为他们试图返回机场然而飞机失速。WPR12LA283描述的就是这样一个例子.
There's a helicopter version of this problem as well. Helicopter crews calculate the "power available" at a given pressure altitude and temperature, and then compare that to the "power required" under those same conditions. The latter are different for hovering "in ground effect"(IGE, with the benefit of a level surface against which their rotor system can push) and "out of ground effect" (OGE, where the rotor system supports the full weight of the aircraft).
有一个直升机版本也是这个问题。直升机机组人员在给定的海拔压力和温度下计算“可用功率”，然后比较在这相同条件下的“电源要求”，后者不同于飞机“地面效应”悬停 而是“无地面效应”悬停。
It's kind of unnerving to take off from, say, a helipad on top of a building and go from hovering in ground effect and moving forward to suddenly find yourself in an OGE situation, not having enough power to keep hovering as you slide out over the edge of the roof.
就是说，直升机在高楼顶部起飞降落场由地面效应起飞， 移动时候突然发现自己是处在无地面效应的情况下，当你滑出屋顶的边缘没有足够的电力保持悬停。这是非常令人不安的。
This is why helicopter pilots always will establish a positive rate of climb from such environments as quickly as possible -- when you get moving forward at around 15 to 20 knots, the movement of air through the rotor system provides some extra ("translational") lift.
这就是为什么在这样的环境中直升机飞行员要尽可能快的建立有利的爬上速度--当你前进的速度在15-20海里/小时 ，空气运动通过转子系统提供一些额外的平移上升。
It also feels ugly to drop below that translational lift airspeed too high above the surface and abruptly be in a power deficit situation -- maybe you have IGE power, but you don't have OGE power. In such cases, you may not have enough power to cushion your landing as you don't so much fly as plummet. (Any Monty Python fans?)
另外令人讨厌的是在水平面上过度升力的空速太高突然电力不足的情况
在这种情况下，你可能没有足够的力量来缓冲着陆，因为你不能一下子垂直下降一样。
Finally, for some insight into the pure aerodynamics at play when airplanes fly too high, I'd recommend reading the responses to What happens to aircraft that depart controlled flight at the coffin corner?
最后，想知道纯航空力学当飞机飞在高处时的东西，推荐阅读Quora“当飞机在航行死角离开控制飞行会发生什么”的回应。
***********************************************************************************到此我的翻译结束，这是我的处女作，英语水平也远远达不到翻译的水平，接下来还请大家吐槽，谢谢~~~
