There's always a risk in flying, but the phase in which a plane is cruising at high altitude is widely considered to be safe. And that's what makes the mystery of what happened to so confounding.
飞行总是存在风险，但人们普遍认为飞机在较高的高度巡航的阶段是安全的。因此马航MH370的失联才如此让人迷惑。

"Whatever happened happened quickly and resulted in a catastrophic departure from the air," Mark Rosenker, former chairman of the National Transportation Safety Board who is now a consultant with CBS news, told NPR's Melissa Block.
美国国家运输安全委员会的前任主席马克·罗森克目前是CBS新闻的一名顾问，他对NPR的梅丽莎·布洛克表示，“不论发生了什么，一定是在瞬间发生，并且导致了飞机在空中发生了灾难性的事故”。

There have been a number of cases in which planes have fallen from the sky — from factors that include catastrophic failure and sabotage. As Patrick Smith, a commercial pilot who runs the popular:
飞机从空中坠落曾经有一些案例，原因包括严重故障和遭到蓄意破坏。民航飞行员帕特里克·史密斯的分析获得了广泛认同：

"All we know for sure is that a plane went down with no warning or communication from the crew. That the crash did not happen during takeoff or landing — the phases of flight when most accidents occur — somewhat limits the possibilities, but numerous possibilities remain. The culprit could be anything from sabotage to an in-flight fire to a catastrophic structural failure of some kind — or, as is so common in airline catastrophes, some combination or compounding of human error and/or mechanical malfunction."
“我们现在唯一清楚的就是飞机没有发出任何警报或通信就发生了事故。而这个事故并没有发生在起飞或降落的时候，这两个阶段是大部分航空事故发生的阶段，所以可能性减少了，但依然存在许多可能。罪魁祸首可能是蓄意破坏，也可能是飞机起火，也可能是重大的结构损坏，或者是许多空难当中的原因，即人为失误加上机械故障。”

Here are some of the problems an aircraft can experience during flight:
飞机在飞行途中可能会遇到下列问题：

Stresses
压力

An aircraft undergoes two kinds of routine stresses: a mechanical stress on the cabin caused by the pressurization and depressurization cycle that happens on each flight; and stress on the plane when it lands.
一架飞机会承受两种必有的压力：一是每架飞机中的增压降低的循环导致的机舱机械应力，二是飞机落地时的压力。

The structural fatigue and damage they cause "are typically taken care of by periodic maintenance," Todd Curtis, an aviation safety analyst who now runs the Foundation, said in an email.
由压力导致的飞机结构性疲劳和损失“一般都通过定期维护来解决”，航空安全分析员托德·柯蒂斯在一封电子邮件中说，他现在运营着航空安全基金会。

The Malaysian Airlines Boeing 777 was last inspected just 10 days ago and was said to be in proper condition. The 777 is a long-haul aircraft that is regarded as safe. , it's had about 60 incidents since it entered service in 1995.
这家马航波音777飞机在10天前刚刚检查过，而且据称状况良好。波音777是一种远程飞机，普遍认为安全性很高。从1995年投入使用以来只发生过60次事故。

Takeoff and landing are typically the riskiest portions of the flight. A Boeing 777 operated by Asiana Airlines was involved in the crash at San Francisco Airport last year that killed three people.
起飞和降落通常是飞行过程中最危险的两个时段。一家韩亚航空的波音777去年在旧金山机场降落时就发生了事故，造成3人死亡。

But the en-route portion of the flight, which the Malaysian Airlines flight was on, is seen as the safest. According to a Boeing analysis, only 9 percent of fatal accidents occur at cruising altitude.
但在飞行途中，也就是马航飞机失联的时段，普遍认为是最安全的。根据一份波音公司的分析，只有9%的致命事故发生在巡航高度。

"Cruise is generally a pretty good place," says David Ison, assistant professor at Embry-Riddle Aeronautical University, who was a transport pilot with international and transoceanic experience. "There's stable conditions. The weather at higher altitudes is generally better. The only issue is turbulence and sometimes thunderstorm activity."
埃姆伯里-利德尔航空学院的助理教授大卫·艾森说，“巡航通常是一个非常不错的阶段”。艾森曾经是一名运输机飞行员，有过国际以及跨洋飞行的经历。“这个阶段条件很稳定。高度越高，天气状况通常越好。唯一的问题是气流，偶尔会有雷暴活动。”

Weather
天气

While weather is a factor at higher altitudes, Flight MH370 was traveling in good weather conditions.
虽然在较高的高度飞行时天气也是需要考虑的因素，但是MH370航班当时的天气状况很好。

Referring to the Malaysian Airlines flight, Curtis said:
关于马航失联航班，柯蒂斯说：

"Weather can be a factor, but it is unclear if it was a factor in this event. One factor that was happening during this event was that the aircraft is flying over the ocean at night. Under these visual conditions, the crew may not be able to look out the window and use the horizon as a sort of backup aircraft altitude indicator. This may make it harder for the pilots to recover the aircraft if it gets into an unusual attitude."
“天气会有影响，但在这次事件中还不清楚这是否是其中一个因素。这次事件有一点，飞机当时是在夜间在海洋上空飞行。在这种视觉条件下，飞行员也许无法看清窗外，利用地平线作为飞机高度的参考。这样一旦飞机的高度出现异常，飞行员想要做出调整难度就会加大。”

Technical/Catastrophic Failure
严重的技术故障

Catastrophic failure can affect one or more critical aircraft structures or systems, making it difficult or impossible for the crew to safely land the aircraft.
严重的故障可能会对一处或多处飞机结构或系统造成影响，从而导致飞行员难以甚至无法让飞机安全降落。

There are exceptions to this, of course. The most famous being the "miracle on the Hudson" in 2009, when U.S. Airways Flight 1549 took off from LaGuardia Airport in New York, struck some birds on its way into the sky, lost both engines and was then successfully guided to a safe landing.
当然也有例外。最著名的一次是2009年的“哈德逊河奇迹”，一家全美航空1549航班从纽约的拉瓜迪亚机场起飞，升空后遭遇鸟击，双引擎失灵，最终依然成功平安降落。

Curtis says, "Because many aircraft systems have backup systems or backup procedures, it usually takes multiple failures to occur before those failures are considered catastrophic or potentially catastrophic."
柯蒂斯说，“因为很多飞机系统都有后备系统或后备程序，如果发生严重的毁灭性的故障，那么一定是发生了多重故障。”

One example of this is Air France Flight 447 that crashed over the Atlantic in 2009. An accident report blamed faulty air speed sensors and pilot error for the crash that killed 228 people.
比如2009年在大西洋坠毁的法航447航班。事故调查报告认为，飞行速度传感器和飞行员操作失误共同导致了这次造成228人死亡的空难。

Ison of Embry-Riddle notes that aircraft today are so reliable that technical failures are highly unlikely in regular operations. In 75 percent to 80 percent of such cases, he notes, the error is human — either by the pilot or by air traffic controllers.
埃姆伯里-利德尔航空学院的艾森认为，今天的飞机都非常可靠，正常操作下不太可能出现技术故障。他认为75%-80%的飞行事故都是人为原因造成的，要么是飞行员的失误，要么是空中交通管理员的失误。

Sabotage
蓄意破坏

Sabotage is the single-biggest reason for en-route accidents, writes Max Kingsley-Jones, a reporter for Flight Global, an aviation magazine.
飞行途中发生的事故，蓄意破坏是最大的原因。一家航空杂志《环球飞行》的记者马克思·金斯利琼斯在报道中这样写。

Here's more from his story:
下面的内容也来自他的报道：

"Including the MAS 777, Ascend Online shows that a total of 46 western-built jet airliners have crashed with the loss of all on board while in the en-route phase. Of these, 13 were caused by sabotage, two more by hijacks and one was shot down. Three more were caused by undetermined causes where flightcrew suicide is suspected."
“包括这次马航777飞机，Ascend网站显示，总共有46架西方生产的飞机在飞行途中完全坠毁。其中13起事故是蓄意破坏导致的，两起是劫机，一起是飞机被击落。还有3起原因不明，飞行员自杀也被怀疑是原因之一。”

And, he notes, "In some cases, in-flight events happen so rapidly that the flightcrew are unable to issue any form of mayday, but it is extremely" unusual.
他还注意到，“在某些案例中，飞行中的状况发生的太突然，以至于飞行员来不及发出任何警报，但这种情况非常少见。”

Pilot's Role
飞行员的角色

When faced with a crisis, the main job of the pilots is to maintain control of the aircraft. That may explain why there was no communication from the Malaysian Airlines plane.
面临危机时，飞行员的主要任务就是保持对飞机的控制。这也许可以解释为什么马航客机没有和地面联系。

"If the pilots are distracted doing something else, then talking to air traffic controllers is not a priority," said John Cox, a former commercial airline pilot who is now CEO of Safety Operating Systems.
“如果飞行员因为做其他事情而分心，那他就不会优先选择和空中交通控制员通话，”安全操作系统的CEO约翰·考克斯说，他曾经也是一名民航飞行员。

Ison notes that in the event there's no communication, it could mean that something catastrophic has happened, or simply that the crew was unaware of what was happening. That was the case, he says, with Air France Flight 447. The pilots "didn't communicate [with air-traffic controllers], even though they had an opportunity to," he said.
艾森注意到，在这起事故中没有任何通信，这也许意味着发生了某些毁灭性的的事故，或者飞行员根本不知道发生了什么。他说，法航447航班事故就是这样。飞行员“并没有和空中交通控制员联系，即使当时他们还来得及这么做。”

The black box recordings in that case showed that the pilots seemed unaware that the plane was going to crash until just seconds before they hit the water.
这起事故中的黑匣子录音表明，飞行员似乎直到飞机坠入海中的前几秒才意识到飞机即将坠毁。

What's Next
接下来该怎样做

The black boxes on that Air France flight were found two years later, and it took investigators until 2012 to piece together what happened on Flight 447. That may also be what's in store for Malaysian Airlines Flight 370.
法航事故中的黑匣子两年之后才找到，调查人员直到2012年才推断出447航班上到底发生了什么。也许马航MH370这次也会面临同样的情况。

"Of course, once this plane is found, it'll be much more clear what may have happened to the aircraft," Curtis said. "In any case, it may be months or years before the true nature of this event is understood."
“当然，一旦找到飞机，查明真相会更加清楚，” 柯蒂斯说。“在任何空难中，都需要花上数月甚至数年才能弄清事故的真相。”

Ison, however, said there's no reason why it takes so long to locate an aircraft after it goes missing.
然而，艾森认为飞机失联后要花如此长的时间来确定位置，是没有理由的。

"In this day and age, having no ability to pinpoint these aircraft is really not acceptable," he said. "We have technology to make it happen. We really need to do something ... so we can prevent the loss of aircraft."
“今时今日依然没有能力定位飞机，这简直不可接受，”他说。“我们有技术做到这一点。我们真的需要采取行动，避免这种空难的发生。”

The holdup, said Rosenker, the former NTSB chair, is cost. One recent study said a U.S. airline with a global network would have to spend at least $300 million per year to transmit its flight data.
美国国家运输安全委员会的前任主席马克·罗森克说，这种事故代价高昂。一项最近的研究表明，一家有全球航线的美国航空公司每年至少需要花费3亿美元来发送它的飞行数据。