Joined: Apr 30, 2004
Location: Caracas - VE o Cochabamba - BO
|Posted: Tue Jan 31, 2006 9:31 pm Post subject: Evalúan varias teorías sobre accidente aéreo en Venezuela
|Evalúan varias teorías sobre accidente aéreo en Venezuela
CARACAS - Las autoridades todavía tiene varias teorías y preguntas sin responder sobre el accidente aéreo ocurrido en Venezuela en agosto, en el que murieron los 160 pasajeros que iban a bordo, declaró el martes una oficial que dirige las investigaciones.
La aeronave de West Caribbean Airways se estrelló en el occidente de Venezuela el 16 de agosto. En el accidente murieron 152 turistas franceses de la isla caribeña de Martinica, y los ocho tripulantes colombianos.
El piloto llamó a la torre de control diciendo que estaban "flame out (apagadas)", las dos turbinas de la nave McDonnell Douglas MD-82 antes de caer a tierra, pero los funcionarios venezolanos han señalado que ellos no creen que las turbinas fallaron, situación que ha incrementado las dudas sobre las causas del accidente.
"Tenemos varias hipótesis", expresó en una conversación telefónica la directora de la Junta de Investigación de Accidentes Aéreos de Venezuela, la teniente coronel Lorllys Ramos Acevedo, quien declinó dar mayores especificaciones.
"Son muchos los factores que tenemos que estudiar para llegar a una conclusión definitiva", agregó Ramos Acevedo, pero precisó que los investigadores está evaluando "el factor humano", así como el funcionamiento de la aeronave y las condiciones climáticas.
Al ser consultada en cuanto a que si las formaciones de hielo en el avión pudieron haber sido un factor que incidió en el siniestro, la funcionaria manifestó que todavía no se puede decir nada al respecto de forma definitiva.
Se prevé que los investigadores podría hacer un reporte con los últimos hallazgos a finales de marzo, pero esto puede tomar más tiempo para ofrecer conclusiones definitivas, expresó Ramos Acevedo.
"Hay muchas preguntas todavía", refirió la funcionaria. "No vamos a descartar ningún factor", añadió.
Expertos franceses, colombianos y estadounidenses han cooperado con las autoridades venezolanas en las investigaciones. Las cajas negras del avión fueron enviadas a Francia para su evaluación.
Un reporte inicial que realizaron en noviembre pasado los investigadores venezolanos señaló que el avión tuvo un ascenso normal desde los 9.450 metros hasta los 10.060 metros, cerca de 20 minutos antes de caer.
Se refiere que el avión se niveló dos minutos después y aceleró con aparente normalidad. Noventa segundos después el avión comenzó a desacelerar sin parar, y luego fue activado el piloto automático.
Al ser interrogada respecto al planteamiento de algunos investigadores en cuanto a que una rápida subida pudo haber afectado el sistema del piloto automático, Ramos Acevedo dijo que "eso es falso".
Grant Brophy, director de seguridad de vuelos y programas de seguridad de Embry-Riddle Aeronautical University en Daytona Beach, Florida, dijo que una gran pregunta es por qué la velocidad del avión comenzó repentinamente a disminuir.
El aparato volaba desde Panamá a Martinica.
Pilots of crashed MD-80 in Venezuela may have missed key directive.
Investigators looking into the crash of a Boeing MD-82 that killed 160 people in August said that the accident occurred after the plane made the kind of rapid climb that Boeing had warned in 2002 should be avoided because the autopilot might power engines back too much when the plane leveled off.
Most of the victims of the Aug. 16 crash in northern Venezuela of the West Caribbean Airways flight from Panama to Martinique were residents of the island territory, which is part of France.
Investigators, who spoke on condition of anonymity because official statements are supposed to come from Venezuela, said that the plane appeared to react just as a 2002 Boeing service bulletin said an MD-82 would react after making a rapid climb from 31,000 feet to 33,000 feet, or 9,450 to 10,000 meters.
The investigators said records they had examined indicated that, after the plane reached 33,000 feet, the autopilot kept working for about six minutes to keep the craft flying at the proper altitude. When the autopilot could do no more, it abruptly shut off as it is designed to do and the crew was suddenly confronted with a jet that needed a larger dose of power and a steady hand to keep it flying.
Investigators said the crew apparently did not notice anything amiss, and may not have been familiar with the 2002 service directive.
As older jetliners are released by major airlines, they are often sold to countries in South America and Africa where training may be less profound than in Europe or the United States, and where such directives do not always reach everyone. The plane was built in 1986 by McDonnell Douglas, which later merged with Boeing.
A Nov. 22 interim official report from the Comite de Investigacion de Acci-dentes Aereos of Venezuela, approved by assisting investigation agencies in France, the United States and Colombia, did not mention the 2002 Boeing bulletin because it had not yet been discovered in the normal investigative process. The report did not reach any conclusions about what caused the crash of the twin-engine Boeing MD-82. A 2002 Boeing bulletin warned that planes in the MD-80 family, including the one that crashed, should not be set on autopilot to climb at too high a rate. After leveling off, Boeing said, the engine power setting could be slightly too low, and "the airplane could decelerate into a stall warning before the autopilot trips off."
That can happen in such a subtle way, the bulletin said, that several minutes could go by while the autopilot is trying to compensate for deteriorating speed, and pilots might not notice until stall warnings suddenly begin sounding. The investigators said that while it was too early to draw any conclusions, that sounds very similar to what happened to the West Caribbean aircraft.
Investigators and aviation professionals, who said they could not be identified because of rules forbidding any information to be released except in official statements, said it was clear that whatever happened, the crew then took actions that would never allow the plane to recover.
The interim report contained a wealth of details from the plane's flight data recorder and cockpit voice recorder, showing that the crew was incorrect in saying that the plane had experienced a "dual engine flameout," and that the crew took the opposite action to recover from an aircraft stall than action that is taught to every beginner pilot. That suggests that the crew did not recognize that the plane was, in effect, stalling.
According to evidence found in the wreckage, the crew pulled the control yoke back toward their chests as they went down, which would raise the nose and lower speed, preventing air from flowing over the wing properly.
The official report said that about 20 minutes before the crash, the plane made a routine climb from 31,000 feet to 33,000 feet. The engines were operating properly at that time, the report said.
About 90 seconds after the plane reached 33,000 feet, it began to slow down for reasons that are not clear. The plane's autopilot began to point the plane's nose up slightly in an effort to compensate for the slowing speed and keep the plane at 33,000 feet. During this time, both engines still appeared to be operating normally, the interim re-port said.
About eight minutes after first leveling at 33,000 feet, the autopilot disengaged and the plane began to descend. The autopilot is designed to disengage on its own if it cannot control an air- craft in extreme situations.
This was about three minutes and 30 seconds before impact. That means the plane was descending at an average of almost 10,000 feet a minute, almost a free fall. A controlled but rapid descent would be about 3,000 feet a minute.
The right engine went to idle shortly after the descent began, although there is no indication why, according to the interim report. It is possible the crew reduced the engine to idle for a moment while trying to troubleshoot their problem. Because of the problem with the flight data recorder, it is unclear what the power settings were on the left engine during this time, although both engines were turning at high speed later at the time of impact.
Almost a minute after the descent began, or two minutes and 46 seconds before impact, the loud stall warning sounded, according to the interim report which has been made public.
After a stall warning sounds, crews are trained to bring the nose of the plane down to allow the plane to gain speed. Stall warnings are designed to engage well before an actual stall, loudly warning the crew of the potential danger.
But the flight data recorder indicated that the crew kept pulling the control yoke backward, reaching a maximum 12 degree nose-up position and holding the yoke there all the way to the ground. The attention of air traffic controllers at Maracaibo was aroused by the crew's sudden and continuous requests for lower altitude.
"The flight crew states that they had a dual engine flameout when asked by ATC if they had a problem," the report said. ATC refers to air traffic control. That was one of the last reports from the plane.
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