Plane crash investigations are incredibly complex, and it can take months or even years to identify what went wrong. But video and photos of the Air India crash on Thursday prompted some early thoughts from aviation experts.

空难调查异常复杂，可能需要数月甚至数年的时间才能查明原因。但周四印度航空坠机事件的视频和照片引发了航空专家的一些初步分析。

A widely shared video of the crash showed the Boeing 787 Dreamliner descending over buildings with its nose pointed upward, an unusual position, said John Cox, a former airline pilot and chief executive of Safety Operating Systems, a consulting firm.

前飞行员、咨询公司安全操作系统的首席执行官约翰·考克斯说，一段被广泛分享的坠机视频显示，这架波音787梦想客机在机头上仰的异常姿态下越过建筑物坠落。

The plane’s position looks as if “it should be climbing, and in fact it’s descending,” he said. “The question is why.”

飞机的姿态看起来“应该是在爬升，实际上却是在下降”，他说。“问题是为什么。”

Mr. Cox and other experts cautioned against jumping to conclusions. Planes and the aviation system have many redundancies to prevent a single problem from leading to a calamity. As a result, crashes are typically caused by multiple failures, which can include equipment malfunctions, improper maintenance, bird strikes or pilot error. Early hypotheses often are ruled out during lengthy, technical crash investigations.

考克斯和其他专家警告不要妄下结论。飞机和航空系统有许多冗余设计，以防单一问题引发空难。因此，坠机通常是由多种失效叠加所致，可能涉及设备故障、维护不当、鸟撞或飞行员操作失误等因素。在漫长的技术性事故调查中，早期的假设往往会被排除。

Officials looking into the crash will have no shortage of questions to ask, said Greg Feith, a former investigator at the National Transportation Safety Board.

美国国家运输安全委员会前调查员格雷格·费斯说，调查此次事故的官员会有很多问题要问。

“Did they properly configure the airplane when it took off? What was occurring with them? Was there a loss of thrust?” he asked. “Was there fuel contamination? Fuel starvation where both engines weren’t getting fuel that would have caused a loss of thrust on both engines?”

“飞机起飞时配置是否正确？飞行过程中发生了什么？是不是失去了推力？”他问。“燃油是否遭到污染？是不是两个引擎都没有得到燃油？这会导致两个引擎都失去推力。”

The N.T.S.B., the lead U.S. agency in crash investigations, said it would send a team to India to help with the investigation, which will be led by India’s aviation authority. The Federal Aviation Administration said it would provide technical expertise and assistance, and its counterpart in Britain, where the flight was headed, made a similar offer.

美国负责空难调查的主要机构美国国家运输安全委员会表示，将派遣一个小组前往印度协助调查，调查将由印度的民航当局牵头。美国联邦航空管理局表示，将提供技术支援，航班目的地英国的相关部门也做出了类似承诺。

In the video, the plane’s descent appeared to be controlled. That suggests that the pilots may have been trying to slow it down, said Ben Berman, a safety consultant who is also a former airline pilot and federal crash investigator in the United States.

在视频中，飞机的下降似乎得到了控制。安全顾问本·伯曼说，这表明飞行员可能一直在试图让飞机减速。他曾任民航飞行员和美国联邦空难调查员。

“Any reduction you can make to the airspeed at impact is going to have a big positive effect,” he said. “It’s consistent with that, but it could also mean any number of other things.”

“任何能够降低飞机撞击速度的操作都会产生显著的积极影响，”他说。“这与视频看到的相符，但也存在其他多种可能性。”

Heat is another consideration. The weather topped 100 degrees in Ahmedabad, the city from which the plane departed on Thursday. High temperatures make takeoffs more difficult because engines produce less thrust and warm air is less dense, making it harder for the airplane to generate lift.

高温是另一个需要考虑的因素。飞机周四起飞的城市艾哈迈达巴德的气温高达38摄氏度左右。高温会增加起飞难度，因为发动机产生的推力会随之降低，热空气的密度更低，这使得飞机更难产生升力。

While the full investigation could take more than a year, corrective actions could potentially arrive sooner, Mr. Feith said.

费斯说，虽然全面调查可能需要一年多的时间，但纠正措施可能会更早出台。

“The whole purpose of accident investigation is to identify safety critical issues — if there’s a problem with the airline, the crew, the airplane itself — you want to get those safety critical issues identified and corrective actions implemented sooner rather than later,” he said.

“事故调查的全部目的是找出重大安全隐患——无论是航空公司、机组人员，还是飞机本身的问题——都必须尽快查明并采取整改措施，”他说。

The plane’s black boxes should provide early insights, too. The information on the flight data recorder includes time, altitude, airspeed and heading. The cockpit voice recorder can offer clues about the moments leading up to the crash, including what the pilots were saying, engine noises, stall warnings or other equipment sounds.

飞机的黑匣子应该也将为初步调查提供关键线索。飞行数据记录仪上的信息包括时间、高度、空速和航向。驾驶舱语音记录器能还原坠机前的关键时刻，包括飞行员说了什么、引擎异响、失速警告或其他设备的声音。

“If they functioned correctly, they’ll give a tremendous amount of information, because the 787 has a huge number of parameters recorded,” Mr. Berman said.

伯曼说：“若黑匣子完好，将提供海量数据。波音787记录的飞行参数极为详尽。”

That data could be recovered and assessed preliminarily within days, Mr. Cox said.

考克斯说，这些数据可以在几天内恢复并进行初步评估。

The footage of the plane’s descent is shaky and grainy, and it wasn’t clear whether the wing’s trailing edge flaps were properly extended as they typically would be when a plane is taking off, experts said. Those flaps, as well as slats at the front of the wing, are typically extended during ascent to provide more surface area and alter the shape of the wing to help lift the plane at relatively low speeds.

专家说，尽管飞机下降的画面不稳定、不清晰，也不清楚机翼后缘襟翼是否如正常起飞时那样适当地展开。这些襟翼以及机翼前部的板条，通常在飞机上升过程中伸展开来，以提供更大的表面积，改变机翼的形状，帮助飞机在相对较低的速度下上升。

“In the video, you see the landing gear is still down, but the flaps look to be in a relatively up position,” Mr. Feith said. “That will have to be examined. Normally on a large aircraft like that, you need to use some level of flap deployment. If the airplane was not properly configured, that can present a performance issue.”

“在视频中，你可以看到起落架仍然是放下的，但襟翼看起来处于一个相对向上的位置，”费斯说。“这一点必须加以研究。通常这样的大型飞机需要襟翼一定程度的展开。如果飞机配置不当，就会出现性能问题。”

Mr. Berman said that typically pilots retract landing gear, which includes the plane’s wheels, quickly after taking off because it can create drag as the plane tries to climb, but not always. The brakes on a larger, heavier jet like the Dreamliner can get very hot, and sometimes pilots may leave the landing gear down for a bit to cool them off, he added.

伯曼说，通常情况下，飞行员会在起飞后迅速收起起落架（包括飞机的机轮），因为它会在飞机试图爬升时产生阻力，但并非总是如此。他还说，像梦想客机这样更大、更重的飞机的刹车可能会变得非常热，飞行员有时会延迟收起起落架以辅助散热。

“It might have been intentional,” he said. “It might have been that they had a massive problem right after takeoff, and they may have neglected to raise the gear. We’ll need to know a lot more about the airplane to comment on this intelligently.”

“这可能是故意的，”他说。“也可能是他们在起飞后出现了严重问题，导致来不及将起落架收起。我们需要有更多的飞行数据，才能做出准确判断。”

The crash on Thursday has some similarity to a 1987 one on Northwest Airlines Flight 255, which crashed in Michigan after the plane’s pilots failed to extend its wing flaps and slats for takeoff. After lifting off, that plane rolled to the left and right and then hit light poles and a rental car building before crashing, killing all but one person on board and several people on the ground. Despite some broad similarities, experts cautioned that the Air India crash could have been from any number of causes.

周四的空难与1987年西北航空公司255号航班的坠机事件有一些相似之处，当时该飞机在密歇根州坠毁，原因是飞行员未能展开机翼襟翼和板条起飞。起飞后，飞机左右剧烈摇晃，撞到电线杆和租车公司大楼，然后坠毁，机上除一人外全部遇难，地面上还有数人罹难。尽管存在一些大体上的相似之处，但专家提醒说，印度航空的这起事故可能有多种成因。