波音737-8到底是一款什么样的飞机？

从蓝天“宠儿”到众矢之的

1967年，波音737原型机实现首飞。

2006年数据显示：平均每秒钟有1,250架波音737正在飞行，每五秒就有一架737正在世界的某个地方进行起降。

截至2018年，已生产超过10,000架的波音737成为全球民航史上最畅销的客机。

而5个月内的两起坠机事故，一时间令波音737整个家族蒙羞。

2018年10月29日清晨，印尼狮航一架波音737 MAX 8飞机从雅加达起飞，竟成了噩梦的开始。飞机仅在13分钟后就和控制台失去联系，随后在印尼爪哇岛近海坠毁。机上189人全部遇难。

On the morning of October 29, 2018, an Indonesian Lion Air flight serviced by a Boeing 737 Max 8 plane with 189 people on aboard crashed shortly after taking off from Jakarta to Pangkal Pinang. All 181 passengers and eight crew members died.

谁也没想到，相似的悲剧在5个月内再次上演。

A similar tragedy happened nearly five month later. 

当地时间2019年3月10日上午8时38分，一架埃航ET302航班在起飞仅6分钟后便迅速坠毁。机上来自30多个国家共157人无一人生还，包括149名乘客和8名机组人员，其中有8名中国乘客。

Ethiopian Airlines Flight 302 went down minutes after takeoff on March 10, 2019 from Addis Ababa, killing all 157 people on board, including 8 from China.

这是继狮航空难后，第二起波音737 MAX 8飞机发生事故。两场悲剧也让波音737 MAX 8机型的安全性在世界范围内受到质疑。

Two crashes within such a short time have brought global attention to aviation safety, and more specifically, Boeing's 737 Max 8 planes.

为确保中国民航飞行安全，中国民航局3月11日发出通知，要求国内运输航空公司于2019年3月11日18时前暂停波音737 MAX 8飞机的商业运行。随后，全球多国和监管机构陆续禁飞波音737 MAX 8全系列或部分机型。美国是最晚宣布禁飞的国家，于3月13日宣布禁飞。至此，所有有波音737 MAX 8型飞机执飞航班的国家和地区都已经停飞了这一机型。

China ordered to ground Boeing 737 Max 8 jets on March 11. Over 50 countries followed suit in four days, shaping a worldwide boycott.

两次掉下来的都是波音737最新一代客机

目前世界上投入使用的只有两个系列的波音737飞机：波音737 Next Generation系列（简称737NG系列，意思是次世代），以及波音737 MAX系列。

There are currently two types of Boeing 737 aircrafts in use across the globe, which are actually quite different with distinctive technology. The Boeing 737 Next Generation (737NG) and its successor the Boeing 737 MAX planes are the two models.

一些媒体在报道中误将失事客机机型翻译成了波音737-800，让不少人立刻慌了——

就是那个我们经常坐的波音737-800掉下来了吗？

别慌，不是。

两次失事的客机属于737 MAX 系列。这一系列包括737 MAX 7, MAX 8, MAX 9和MAX 10。

更确切的说，两次坠毁客机均是737 MAX系列中的737 MAX 8，也称波音737-8，它在2017年5月刚刚完成首次交付，距今还不到2年时间。

而这个波音737家族中的“新秀”却在5个月的时间内造成两起机毁人亡、无一人生还的重大空难事故，简直令人费解。

问题出在哪儿？

While the 737 MAX series incorporates Boeing's latest technology, it has also become a growing worry among the global airline industry with its 737 MAX 8, or 737-8 plane at the center of both crashes.

“罪魁祸首”是“MCAS”吗？

2011年，波音在宣布737 MAX的研发计划时称，737 MAX将会成为单通道飞机市场有史以来“最省油、运营成本最低”的全新机型。

When Boeing unveiled its plans for 737 MAX in 2011, it said that the new aircraft would be "the most fuel efficient, most capable airplane with the lowest operating costs in the single-aisle market."

然而，最新一代的737 MAX系列飞机被安装了一个其它737家族的飞机都没有的系统，而这个系统也成为两起坠机事故的调查重心——它就是被称为“MCAS”（Maneuvering Characteristics Augmentation System）的自动防失速系统。

There is one thing that differentiates Boeing 737 MAX from previous 737s – the re-engined 737 MAX is equipped with a system known as the Maneuvering Characteristics Augmentation System, or MCAS. This system has now become a focus of investigators.

MCAS was introduced by Boeing on the 737 Max aircrafts because of the heavier, more fuel-efficient engines, which changed the aerodynamic qualities of the workhorse aircraft and can cause the plane's nose to pitch up in certain conditions during manual flight.

737 MAX飞机换装了直径更大更省油的先进发动机，但这一换装有一个致命缺陷，它容易导致飞机在大迎角飞行失速。为了解决这个缺陷，波音研发了“MCAS”这一自动防失速系统随时监测飞机迎角：如果迎角超过了安全界限，就会自动压低机头进入可能长达10秒之久的俯冲增速状态。

Angle of attack sensors on the aircraft tells the MCAS to automatically point the nose of the plane downward if it is at risk of going into a stall.

然而，这一原本为了防止飞机失速而研发的安全系统却很可能成为两次空难的“罪魁祸首”：

因为一旦传感器误读数据，该系统会误判飞机姿态，而优先级极高的这一系统会直接绕过飞行员进行俯冲加速，化解并不存在的“失速”。

However, problems could arise if the MCAS system gets wrong sensor readings. In that case, the system would automatically put the plane in a steep dive that could last as long as 10 seconds, overriding the pilots' commands.

According to the flight data recorder, the pilots of Lion Air Flight 610 struggled to control the aircraft as the automated MCAS system repeatedly pushed the plane's nose down following takeoff.

The pilots of the Ethiopian Airlines plane reported similar difficulty before the aircraft plunged into the ground shortly after takeoff.

也许系统设计的缺陷难以预知，但令人不解的是，波音在737 MAX的介绍手册中没有公开这一机型新增了自动防失速系统这一重要信息，也没有对可能导致飞机俯冲的这一关键功能进行任何警告。

更令人瞠目结舌的是，据《纽约时报》报道，许多驾驶737MAX机型的飞行员，因其有737机型的飞行经验而被认定不需要接受新机型的模拟机训练，而仅仅通过iPad软件学习这个新机型。

As to the pilot training regarding the new 737 MAX aircrafts, there was hardly any at all, according to a recent report by The New York Times. 

The Federal Aviation Administration determined that there were not enough differences between the new model and the prior iteration of 737 to require pilots to go through simulator training when Boeing first rolled out the 737 MAX 8. As a result, though astonishing, many pilots with 737 experience learned about the new model on an iPad.

两起坠机事故有“明显的相似之处”

埃塞俄比亚交通部一名发言人17号表示，对埃航坠机黑匣子的初步分析显示，这起空难与去年10月印尼狮航波音737-8客机发生的空难有“明显的相似之处”。发言人还提到，将在30日内发布上周坠机的初步调查报告。

Black box data recovered from an Ethiopian Airlines plane that crashed last week show "clear similarities" with a recent crash in Indonesia of the same type of aircraft, Ethiopia's transport minister said on Sunday.

While declining to give details, Dagmawit Moges told journalists the parallels would be the "subject of further study during the investigation," with a preliminary report issued in 30 days.

但不管怎样，现在作何结论都言之过早。

真相如何，我们拭目以待。

Sources: The New York Times, CBS, CNN, 央视新闻