20090216/美客机黑匣子揭秘：坠毁前经历恐怖26秒

美国联邦航空局的官员2月15日发表声明称，导致12日晚，一架美国大陆航空公司的客机在水牛城附近坠毁，并造成50人死亡的事故原因，是因为在冰冻环境下，飞行员错误地启动了自动驾驶功能，导致飞机降落过程中失控。

美联社报导，美国国家运输安全委员会(National Transportation Safety Board)官员史蒂夫·切兰德(Steve Chealander)称，科尔根航空公司(Colgan Air)建议飞行员在冰冻环境下手动驾驶飞机。飞行员都会被要求按照这一建议在冰冻天气状况下手动操控飞机。

遇事飞机的飞行员曾在飞机坠毁之前报告称，飞机的前挡风玻璃和两侧的机翼上都结上了冰。切兰德还说道，根据现场的初步调查可以得知飞机在坠毁后其自动驾驶功能处于启动状态。

美国调查人员15日宣布，本月12日在纽约州布法罗市坠毁的客机直到触地爆炸前26秒才发生“无法控制的异常状况”，结果造成50人不幸遇难。当时，这架一直处于“正常飞行状态并准备降落”的飞机突然失去控制，并因失速而“直挺挺”地从空中“拍”在机场附近的居民房上起火燃烧。

从飞机“黑匣子”中记录的数据看，当时机上的除冰设备处于启动状态。不过，有关方面拒绝透露这个关键设备是否工作正常。据介绍，机组发现飞机结冰时，正处在距地面3000多米的空中，并且做好了降落准备。在飞机距地面还有600多米时，驾驶员成功放下了起落架，20多秒后，飞机打开减速板，此后竟翻滚着扎向地面。

人民网报导，从事故现场看，坠机地点距离机场跑道不足10公里。飞机出现故障时，其航行高度只有600多米，并且在5秒钟内下降了300米。在这种情况下，飞行员根本无法采取有效措施来挽救机毁人亡的命运。调查人员从飞机残骸的驾驶挡风玻璃和机翼前端都发现了大量结冰现象。机组人员在飞机坠毁前曾向塔台报告此事。

失事客机黑匣子所记录的数据显示，机舱语音记录在遭到巨大撞击后才终止。此前26秒时，舱内响起报警声，提醒飞行员这架客机正在失去动力，并可能因此失速坠毁。紧接着，机上的自动驾驶仪将机头压低，以便保持速度，并切换到了手动驾驶状态。突然，机头向上抬高到了与海平面呈31度角的位置。

坠机地点火光冲天

据悉，上述角度远远大于失事客机能承受的爬升仰角。目前尚不清楚，机组以如此大角度抬高机头是否为“下意识反应”。转眼间，飞机开始向下扎，机头很快就与海平线呈-45度角，如同战斗机那样向地面俯冲。与此同时，机身先向左侧倾斜45度，然后又向右倾斜翻超过106度，最终机腹着地摔在了一座房屋上。

调查人员指出，在飞机坠毁前的“翻滚过程中”，机组和乘客经受的过载压力超过地面正常水平的两倍（相当于每个人身上都压上了大于自己两倍体重的重物），其中滋味可想而知。这种情况再加上坠毁瞬间的猛烈撞击以及熊熊烈火，遇难人员的身份多数要通过对遗体进行DNA测试或者牙医纪录才能确定。

有人怀疑，失事飞机隶属的航空公司为了节约成本，可能会雇佣“新手”开飞机。不过，有关资料显示，这位机长已有3379个小时飞行经验，并从去年12月开始操作坠毁的“冲锋-8”型客机。该机副驾驶是位有着2244小时飞行经验的女性，她接触“冲锋-8”客机的时间更是高达774小时之多，他们都不存在经验不足的问题。

调查人员指出，这架失事客机的飞行员在冰雪天气中使用自动驾驶仪，结果掩盖了飞机系统中不正常的工作状态。据悉，美国政府航空管理部门曾规定，在冰雪天气中，最好手动驾驶飞机，以便及时掌握飞机因体表结冰而发生的“操控不灵”现象，并且提前采取应对措施，但这一要求不是强制性的。

不过，据失事飞机使用手册上规定：除非天气（结冰现象）“异常严重”，否则驾驶员可正常使用机上的自动驾驶仪，此举反而能让飞行状态更加平稳。此外，机组在从纽瓦克起飞升空后，立刻就打开了机上的除冰设备。在分析了相关气象资料后，人们发现航线上的天气情况不算太反常，这让上述机身结冰现象的原因成了谜。

美国调查机构表示，找到本次空难正式原因需要花费18个月左右的时间。目前，救援人员正在抓紧工作，以便在一场新的暴风雪到来之前，将遇难者遗体抢救出来，然后再把飞机残骸和被烧毁的房屋废墟清理干净，整个过程可能需要数周时间才能完成。因此，目前有关事故原因的种种说法，都是“推测”。

出事飞机为加拿大庞巴迪公司生产的“冲锋-8Q400”型74座支线客机。航空公司表示，这架飞机刚出厂不久，而且拥有很好的安全纪录。目前，共有220架同型号飞机在世界各地的航空公司中运送旅客，是中小航空公司和中程以下航线的“宠儿”，但“冲锋-8Q400”型客机除冰性能一般，容易发生机体结冰现象。

2007年，这种飞机曾因在三天内发生两次严重事故而根据厂家要求全部停飞接受检查。不过，本次事故的调查人员已经确信，在布法罗坠毁的“冲锋-8”客机上的两台发动机“工作正常”。资料显示，“冲锋-8”中型客机配有两部涡轮螺旋桨发动机，可比相同级别的喷气式飞机节油30-40%左右。这样，在800公里以内的短途航线上，此类“老式螺旋桨”飞机的竞争力远远强于波音-737飞机。目前，庞巴迪公司正在开发一种可搭乘90名乘客的世界上最大的涡轮螺旋桨客机，以便占据更大的市场份额。

《时代》周刊宣称，在布法罗坠毁的“冲锋-8”型飞机安全纪录欠佳，2007年加拿大庞巴迪公司曾下令凡是有一万次起降记录的“冲锋-8”型飞机，必须要停飞接受检查。此前，这种飞机曾经在三天内发生了两次严重事故。目前，共有220架同型号飞机在世界各地的航空公司中运送旅客。

这种售价2400万美元的中型客机配有两部涡轮螺旋桨发动机，比相同级别的喷气式飞机节油30-40%。在800公里以内的短途航线上，这种飞机的竞争力远远强于波音-737飞机。目前，庞巴迪公司正在开发一种可搭乘90名乘客的世界上最大的涡轮螺旋桨客机，以便占据更大的市场份额。

就在美国发生机毁人亡事故后不到24小时，一架英国航空公司的客机在伦敦机场降落时前起落架断裂，结果让飞机在“脑袋贴地”的情况下滑行了相当距离。所幸，机上71名乘客和机组人员中，只有一人受轻伤，其他人都安全逃离了现场。

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Pilot’s actions under scrutiny in Buffalo crash

Feb 16, 2009 12:20 PM

THE ASSOCIATED PRESS

BUFFALO, N.Y.—The sounds of the last desperate minutes in the cockpit aboard Flight 3407 could be clues to the cause of a crash that came violently and suddenly, with the doomed plane dropping steeply and pitching and rolling like a rollercoaster.

Investigators in Washington and Buffalo have begun an in-depth study of the plane’s voice cockpit and voice data recorders.

They also plan to scrutinize all pieces of the engines to learn whether the Canadian-built plane was intact when it hit the ground. Steve Chealander of the National Transportation Safety Board said the engines would be taken by crane from the debris field Monday.

Families of the victims were hoping to visit the site as well, Chealander said.

On Sunday, Chealander released facts illustrating how the Continental Connection flight disappeared from radar late Thursday, plunging into a house and killing 50 people.

Chealander said information from the plane’s flight data recorder indicated that the aircraft pitched up at an angle of 31 degrees in its final seconds, then pitched down at 45 degrees.

The plane rolled to the left at 46 degrees, then snapped back to the right at 105 degrees — 15 degrees beyond vertical.

Radar data shows Flight 3407 fell from 1,800 feet, or 550 metres, above sea level to 1,000 feet, or 300 metres, in five seconds, he said. Passengers and crew would have experienced G-forces up to twice as strong as on the ground.

Authorities said Monday that gawkers continue to seek access to the site, forcing officials to again close a road that leads to the suburban Clarence neighbourhood where the plane crashed into a house, killing all 49 people on board and one person in the home. The victims included one Canadian.

A road that leads to the neighbourhood was reopened to traffic about 6 p.m. Sunday but closed again after residents complained that people were parking cars and then trespassing on backyards in a bid to get close, according to Capt. Steven Nigrelli of the New York State Police.

Three people have been arrested trying to get to the site, including a man caught hiding behind a home and videotaping the crash site Friday.

The plane crashed belly-first on top of a house about 10 kilometres short of Buffalo Niagara International Airport, two to three minutes from when it should have touched down on the runway.

Just before the plane went down, the pilots discussed “significant” ice buildup on their wings and windshield. Other aircraft in the area told air traffic controllers they also experienced icing around the same time.

Chealander said in an interview that the pilot may have rejected federal safety recommendations and the airline’s own policy for flying in icy conditions by leaving the autopilot on even after he notified air traffic control that the flight crew had spotted ice on the leading edge of the wings and the windshield.

The Bombardier Dash 8 Q400 plane, operated by Colgan Air, was equipped with a “stick shaker” and “stick pusher” mechanism that rattles the yoke to warn the pilot if the plane is about to lose aerodynamic lift, a condition called a stall. If not corrected in time, the mechanism automatically pushes the stick forward to avert a stall.

Chealander said the plane was on autopilot until the “stick shaker” and “stick pusher” kicked in, automatically putting the plane back in the pilot’s hands.

At some point, the pilot switched on an anti-stall device that increases the speed of the plane by 20 knots and gives a pilot more margin to recover from a stall if it occurs.

Asked whether the pilot might have overreacted by pulling the stick back when it automatically went forward, Chealander said, “Yes, it’s possible.”

Still, he was careful not to be critical of the pilot.

“Everything that should have been done was done, so we keep looking,” he said. “We keep looking, trying to find out why this happened.”

Chealander said the plane’s de-icing system was turned on 11 minutes after it took off from Newark, N.J., and stayed on for the entire flight. Indicator lights showed the system appeared to be working.

He said the pilot was being “very conservative” by turning it on so soon.

Investigators who examined both engines said they appeared to be working normally at the time of the crash.

Colgan Air operates a fleet of 51 regional turboprops for Continental Connection, United Express and US Airways Express.

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Victims of the crash of Flight 3407

Updated: 02/15/09 04:39 PM

The following people are confirmed victims of the Flight 3407 crash Thursday in Clarence. A complete list of the 49 people on the flight from Newark, N.J., to Buffalo has not been released by the airline or by authorities. These names have come from a variety of sources, including friends and family.

? MARY JULIA ABRAHAM, 44

? GEORGE ABU-KAREM, 27,TIBERIAS, ISRAEL

? DAVID M. BORNER, 49, PENDLETON

? LINDA DAVIDSON, 61, WESTFIELD

? RONALD DAVIDSON, 66, WESTFIELD

? ALISON L. DES FORGES, 66, BUFFALO

? BEVERLY ECKERT, 57, STAMFORD, CONN.

? JOHN FIORE, 60, GRAND ISLAND

? BRAD GREEN, 53, AMHERST

? RON GONZALEZ, 44, NEW BRUNSWICK, N. J.

? ZHAOFANG GUO, 53, AMHERST

? KEVIN JOHNSTON, 52, EAST AMHERST

? STEVE JOHNSON, NORTHROP GRUMMAN EMPLOYEE

? ELLYCE KAUSNER, 24, CLARENCE

? NICOLE KORCZYKOWSKI, NEW YORK CITY

? JEROME KRASUSKI, 53, CHEEKTOWAGA

? BETHANY KUSHNER, 19, ANGOLA

? SEAN LANG, 19, MONTGOMERYVILLE, PA.

? MADELINE LOFTUS, 24, PARSIPPANY, N. J.

? LORIN MAURER, 30, PRINCETON, N. J.

? COLEMAN MELLETT, 34, EAST BRUNSWICK, N. J.

? DON MCDONALD, 48, FORT ERIE, ONT.

? DAWN MOSSOP, 48, BLOOMFIELD, N. J.

? DONALD MOSSOP, 42, BLOOMFIELD, N. J.

? SHAWN MOSSOP, 12, BLOOMFIELD, N. J.

? JENNIFER NEILL, 34, CLARENCE

? GERRY NIEWOOD, 64, GLEN RIDGE, N. J.

? JOHNATHAN PERRY,27, NEW YORK CITY

? MARY “BELLE” PETTYS, 50, WEST SENECA

? DONNA PRISCO, 52, RANDOLPH, N. J.

? MATILDA QUINTERO, 57, WOODBRIDGE, N. J.

? FERRIS REID, 44, BLOOMFIELD, N. J.

? CAPT. MARVIN RENSLOW, 47, LUTZ, FLA..

? JOHN ROBERTS III, 48, INDIA

? REBECCA SHAW, 24, MAPLE VIEW, WASH.

? JEAN SRNECZ, 59, CLINTON, N. J.

? DARREN TOLSMA, 45, LANCASTER

? SUSAN WEHLE, 55, AMHERST

? ERNEST WEST, 54, CLARENCE

? DOUGLAS C. WIELINSKI, 61, CLARENCE

? CLAY YARBER, 62, RIVERSIDE, CALIF.

? CAPT. JOSEPH ZUFFOLETTO, 27, JAMESTOWN

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Final descent was nearly 20 times faster than normal

Updated: 02/16/09 12:39 PM

Mary B. Pasciak and Aaron Besecker
NEWS STAFF REPORTERS

Everything seemed normal for the first 59 minutes and 34 seconds of Flight 3407 from Newark to Buffalo.

But the last 26 seconds launched a terrifying descent in which the crew tried to regain control of the plummeting plane as it was rolling and twisting, according to information retrieved from the two black box recorders of the ill-fated plane and released Sunday.

A minute before the plane crashed, nothing appeared amiss. The autopilot was controlling the descent at 154 mph, the landing gear and flaps were lowered, and, at 1,650 feet above the ground, the plane was on course for landing on Runway 23 at Buffalo Niagara International Airport.

But 34 seconds later, the plane suddenly went out of control and began a deadly roller-coaster descent that ended at 10:20 Thursday night.

The pilot and first officer heard a warning tone, signaling that the autopilot had automatically disengaged.

Instead of easing toward the landing strip at a gradual descent, the nose of the plane suddenly pitched up at a 31-degree angle, far steeper than what’s normal for a plane during takeoff.

At that point, it appears that the crew took over from the autopilot and rammed the throttles all the way forward, trying to prevent the plane from stalling.

Seconds later, the nose of the plane dipped dramatically. At the same time, the plane rolled to the left, its left wing dipping and the right wing pointing up. Then the plane rolled even more dramatically to the other side.

Inside the cabin, passengers and crew felt a gravitational pull of two Gs, twice the force of gravity.

The wings then came back toward level flight. But the nose of the plane still pointed down, and the plane was pointed in the opposite direction from the airport. It had reversed direction.

Continental Connection Flight 3407 also was dropping nearly 20 times faster than normal … falling 800 feet in 5 seconds. The last recorded data showed the plane 250 feet above ground level, at 115 mph, less than 5 seconds before impact.

Finally, the plane hit flat on the ground, igniting a fireball that took the lives of all 49 people onboard and one in the Clarence Center house it struck.

That is the terrifying sequence of events that federal investigators reconstructed for reporters Sunday evening in a hotel in Amherst.

What caused the plane to pitch out of control and crash remains a question, according to representatives from the National Transportation Safety Board. But some of the details of the final moments of the flight have started coming to light.

It is too early to determine what role icing played, said Steven R. Chealander, the NTSB member overseeing operations locally. The flight’s crew had reported “significant” icing on the windshield and leading edge of the wings. “Significant,” however, is not a technical term, but merely the words the crew chose to describe what they saw.

Icing is categorized by the Federal Aviation Administration as light, moderate or severe.

“We have not gotten reports yet suggesting it was severe icing,” Chealander said.

The takeoff of Flight 3407 was delayed for more than two hours from New Jersey on Thursday night, departing at 9:20. The delay, though, was related to winds as high as 57 mph in the metropolitan New York City area, Chealander said, not because of any weather conditions in the Buffalo area.

“It really was not a bad weather day, and they chose to launch,” he told reporters gathered at the Buffalo/Niagara Marriott in Amherst.

The crew turned on the de-icing system 11 minutes after takeoff, and it remained on throughout the flight, he said.

As in most routine flights, autopilot was engaged, controlling the plane’s maneuvers prior to landing. But the autopilot shut off just half a minute after the landing gear was lowered, signaling to the flight crew that conditions were too extreme for autopilot to handle.

As federal investigators continue to comb through the evidence, the level of icing is likely to become a key factor. The manufacturer of the twin-engine Bombardier Dash 8 Q400 turboprop recommends that in “severe” icing, autopilot be disengaged so the pilot can correct for weather conditions more efficiently, Chealander said.

In general, the NTSB recommends that when icing occurs, “you might want to disengage the autopilot so you have a manual feel for what might be changing because of the ice,” he said.

“We suggest you take it off autopilot to better feel the airplane and stay ahead of changes as a result of the icing,” he said.

But the FAA offers a different recommendation to pilots who encounter icing conditions.

This federal agency encourages pilots to “use the autopilot to help you handle the workload in these highly intense weather situations. To say they shouldn’t have been flying on autopilot is not correct,” Chealander said.

The FAA has not adopted the NTSB’s guidelines.

And that point, in the months ahead, may become a point of contention between the FAA, which regulates aviation, and the NTSB, which is charged with investigating various types of transportation accidents.

“The FAA sees things a little differently than we do,” said the NTSB’s Chealander.

Both organizations are federal agencies under the umbrella of the Department of Transportation. Neither has direct oversight of the other.

Investigators are continuing to dig through the debris on Long Road in Clarence, still searching for the remains of victims, as well as pulling out plane parts. “The plane doesn’t seem to have lost anything prior to impact,” Chealander said.

Crews have found all six blades to Engine 2, he said. Engine 1 was consumed by fire, but fragments of four blades, all badly burned, have been found.

A crane is being used to lift the engines and put them on the road for investigators to examine, he said.

In addition to its de-icing system consisting of pneumatic boots and electrically heated propellers, the plane also has a related, “sophisticated” system that helps deal with icing, Chealander said.

If the pilot flips the “reference speed increase switch,” the instruments add a margin to the “stall speed,” or the speed at which the wings no longer create lift and the plane drops.

“It basically adds 20 knots [about 23 mph] to everything you’re doing to help protect you against a stall,” he said. “From every indication that we’ve got right now off [the] flight data recorder and so forth, that switch was engaged.”

Chealander said airline representatives have told the safety board that all pilots received training in winter operations prior to this season. During that training, pilots were instructed they should activate de-icing systems before the planes enter icing conditions, he said.

The NTSB will continue to piece together evidence and try to determine what caused the disaster. But that may require considerable time.

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