China Airlines B747 Crash (Merged)
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"The resulting deduced track-plot of "debris" might be totally skewed
by invalid data. And so the end result of any multi-radar correlated
plot might be so much wishful thinking (or at best, the best guess,
and possibly useless for any meaningful deductions)."
UNCTUOUS, that was my point. The ASC called the reverse direction
track "puzzling" for good reason. Until it is understood it can't
really be used to support any particular theory. A long time ago
I worked on radar problems that involved deliberately introduced
"debris." Balancing the two possible errors of a statistical
decision algorithm (false positives and false negatives) is an
especially tricky problem in this setting.
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Excerpted from the June 6 Taipei Times
Data show flight CI611 broke up during ascent
With the assistance of data provided by China, authorities have also
concluded that the plane's speed and heading were highly erratic before
the accident.
Chinese radar data given to Taiwan has helped confirm that the
ill-fated China Airlines flight CI611 broke into four pieces during
its ascent, an official from the Aviation Safety Council said yesterday.
Council Managing Director Yong Kay (¦¥³Í) yesterday confirmed
that the plane broke apart at an altitude of between 10,360m and
11,250m and that the aircraft's speed and heading were highly
erratic in the moments before the disaster.
"The data are very consistent. It shows the plane had not
reached cruising altitude when the accident occurred,'' said
Yong.
"Before today, we thought that the plane had actually reached its
cruising altitude -- which is at about 10,668m."
Meanwhile, radar information provided by Beijing's Chinese Civil
Aeronautics Administration shows that the aircraft flew at varying
speeds and in the wrong direction two minutes before it hit the
water. Taiwan's radar systems failed to register this data, officials
said.
"To sum up the information that we have, we can confirm that the
aircraft broke into four pieces. According to the radar data, one
piece of the debris reached a height of 11,250m after the plane
broke up" Yong said.
"In addition, Chinese radar information shows that the plane
briefly flew at the wrong speed and in the wrong direction before
it crashed. Unfortunately, we do need the `black boxes' -- the
flight data recorder and the cockpit voice recorder -- to confirm
our observations."
Yong said radar data shows that it took approximately 1 minute
and 40 seconds for the biggest and heaviest debris to fall into the
sea and 1 hour and 30 minutes for the lightest piece to "float"
down and finally land.
After the crash, Tainan radar recorded unidentified material
"floating" in the air and finally disappearing above Changhua
County.
Aircraft passengers' belongings, found by investigators in the
Changhua area, confirm the radar information.
Data show flight CI611 broke up during ascent
With the assistance of data provided by China, authorities have also
concluded that the plane's speed and heading were highly erratic before
the accident.
Chinese radar data given to Taiwan has helped confirm that the
ill-fated China Airlines flight CI611 broke into four pieces during
its ascent, an official from the Aviation Safety Council said yesterday.
Council Managing Director Yong Kay (¦¥³Í) yesterday confirmed
that the plane broke apart at an altitude of between 10,360m and
11,250m and that the aircraft's speed and heading were highly
erratic in the moments before the disaster.
"The data are very consistent. It shows the plane had not
reached cruising altitude when the accident occurred,'' said
Yong.
"Before today, we thought that the plane had actually reached its
cruising altitude -- which is at about 10,668m."
Meanwhile, radar information provided by Beijing's Chinese Civil
Aeronautics Administration shows that the aircraft flew at varying
speeds and in the wrong direction two minutes before it hit the
water. Taiwan's radar systems failed to register this data, officials
said.
"To sum up the information that we have, we can confirm that the
aircraft broke into four pieces. According to the radar data, one
piece of the debris reached a height of 11,250m after the plane
broke up" Yong said.
"In addition, Chinese radar information shows that the plane
briefly flew at the wrong speed and in the wrong direction before
it crashed. Unfortunately, we do need the `black boxes' -- the
flight data recorder and the cockpit voice recorder -- to confirm
our observations."
Yong said radar data shows that it took approximately 1 minute
and 40 seconds for the biggest and heaviest debris to fall into the
sea and 1 hour and 30 minutes for the lightest piece to "float"
down and finally land.
After the crash, Tainan radar recorded unidentified material
"floating" in the air and finally disappearing above Changhua
County.
Aircraft passengers' belongings, found by investigators in the
Changhua area, confirm the radar information.
Last edited by bblank; 6th Jun 2002 at 06:34.
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>"In addition, Chinese radar information shows that the plane
briefly flew at the wrong speed and in the wrong direction before
it crashed."<
I fear something is being lost in the translation, and clarity may have to await release of the radar track values for all four parts of the plane. It is hard to envision how an intact plane could achieve the values already published, such as for the 36 seconds below:
time/heading/speed/altitude
15:28.31 224/452/347
15:28.43 070/413/347
15:28.55 057/417/369
15:29.07 186/241/351
For what its worth, a similar number of TW 800 bodies were recovered floating on the seasurface as were recovered from CI611. Approximately 10 percent of the TW800 floating bodies showed evidence of thermal burns, generally first and second degree. Apparently, there is no indication of burns on the CI 611 bodies recovered from the seasurface.
briefly flew at the wrong speed and in the wrong direction before
it crashed."<
I fear something is being lost in the translation, and clarity may have to await release of the radar track values for all four parts of the plane. It is hard to envision how an intact plane could achieve the values already published, such as for the 36 seconds below:
time/heading/speed/altitude
15:28.31 224/452/347
15:28.43 070/413/347
15:28.55 057/417/369
15:29.07 186/241/351
For what its worth, a similar number of TW 800 bodies were recovered floating on the seasurface as were recovered from CI611. Approximately 10 percent of the TW800 floating bodies showed evidence of thermal burns, generally first and second degree. Apparently, there is no indication of burns on the CI 611 bodies recovered from the seasurface.
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Possibly Relevant
1.17.01 Previous Cargo Door Incident
On March 10, 1987, a Pan American Airways B-747-122, N740PA,
operating as flight 125 from London to New York, experienced an incident involving the forward cargo door. According to Pan Am and Boeing officials who investigated this incident, the flightcrew experienced pressurization problems as the airplane was climbing through about 20,000 feet. The crew began a descent and the pressurization problem ceased about 15,000 feet. The crew began to climb again, but about 20,000 feet, the cabin altitude began to rise rapidly again. The flight returned to London. When the airplane was examined on the ground, the forward cargo door was found open about 1 1/2 inches along the bottom with the latch cams unlatched and the master latch lock handle closed. The cockpit cargo door warning light was off.
According to the persons who examined the airplane, the cargo door had been closed manually and the manual master latch lock handle was stowed, in turn closing the pressure relief doors and extinguishing the cockpit cargo door warning light. Subsequent investigation on N740PA revealed that the latch lock sectors had been damaged and would not restrain the latch cams from being driven open electrically or manually. It was concluded by Boeing and Pan Am that the ground service person who closed the cargo door apparently had back-driven (opened) the latches manually after the door had been closed and locked. The damage to the sectors, and the absence of other mechanical or electrical failures supported this conclusion. Further testing of the door components from N740PA and attempts to recreate the events that led to the door opening in flight revealed that the lock sectors, even in their damaged condition, prevented the master latch lock handle from being stowed, until the latch cams had been rotated to within 20 turns (using the manual 1/2 inch socket drive) of being fully closed. A full cycle, from closed to open, is about 95 turns with the manual drive system.
1.17.01 Previous Cargo Door Incident
On March 10, 1987, a Pan American Airways B-747-122, N740PA,
operating as flight 125 from London to New York, experienced an incident involving the forward cargo door. According to Pan Am and Boeing officials who investigated this incident, the flightcrew experienced pressurization problems as the airplane was climbing through about 20,000 feet. The crew began a descent and the pressurization problem ceased about 15,000 feet. The crew began to climb again, but about 20,000 feet, the cabin altitude began to rise rapidly again. The flight returned to London. When the airplane was examined on the ground, the forward cargo door was found open about 1 1/2 inches along the bottom with the latch cams unlatched and the master latch lock handle closed. The cockpit cargo door warning light was off.
According to the persons who examined the airplane, the cargo door had been closed manually and the manual master latch lock handle was stowed, in turn closing the pressure relief doors and extinguishing the cockpit cargo door warning light. Subsequent investigation on N740PA revealed that the latch lock sectors had been damaged and would not restrain the latch cams from being driven open electrically or manually. It was concluded by Boeing and Pan Am that the ground service person who closed the cargo door apparently had back-driven (opened) the latches manually after the door had been closed and locked. The damage to the sectors, and the absence of other mechanical or electrical failures supported this conclusion. Further testing of the door components from N740PA and attempts to recreate the events that led to the door opening in flight revealed that the lock sectors, even in their damaged condition, prevented the master latch lock handle from being stowed, until the latch cams had been rotated to within 20 turns (using the manual 1/2 inch socket drive) of being fully closed. A full cycle, from closed to open, is about 95 turns with the manual drive system.
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Is anybody else suspicious that the recorders have not been found? Surely by now they would be. I wonder if they have been recovered and the data is not such that the authorities want known? Conspiracy, anyone?
Is anybody else suspicious that the recorders have not been found? Surely by now they would be
Moderate, Modest & Mild.
I hate to admit it, yellow dust, but I expressed EXACTLY those words to the F/O I was with today.
TWO WEEKS, and the "black boxes" have STILL not been recovered??!!
TWO WEEKS, and the "black boxes" have STILL not been recovered??!!
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I believe that the reason for the lack of recovery of the Black Boxes has at least in part been the presence of a typhoon in the area. This is Typhoon Naguri, which is currently situated off the NE coast of Taiwan, having routed from the South China Sea to the south of Hang Kong, initially eastwards then northwards parallel to the Taiwan coast.
Although the typhoon has been some distance from the crash site, it is enough to cause signifcant swells that make underwater operations in the shallow water of the Taiwan Straights very difficult. It is likely that the debris is also being redistributed by these processes.
Unfortunately we are now at the start of the typhoon season, so recovery of the debris is urgent.
Incidentally, the typhoon may also be an interesting factor in Wednesday's World Cup match, being forecast to route along the east coast of Japan over the next two days.
Dr Dave
Although the typhoon has been some distance from the crash site, it is enough to cause signifcant swells that make underwater operations in the shallow water of the Taiwan Straights very difficult. It is likely that the debris is also being redistributed by these processes.
Unfortunately we are now at the start of the typhoon season, so recovery of the debris is urgent.
Incidentally, the typhoon may also be an interesting factor in Wednesday's World Cup match, being forecast to route along the east coast of Japan over the next two days.
Dr Dave
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Good grief! It's never too early for conspiracy theories, is it?
American Underwater Search and Survey, the outfit used by the NTSB, is
on hand mapping the seabed. They may be hampered by weather as Dr. Dave
has suggested, but, according to the ASC, nothing is being recovered
because Taiwan lacks the specialized equipment needed for the salvage.
They have hired Global Industries for that.
The divers and equipment are not scheduled to arrive until June 14.
American Underwater Search and Survey, the outfit used by the NTSB, is
on hand mapping the seabed. They may be hampered by weather as Dr. Dave
has suggested, but, according to the ASC, nothing is being recovered
because Taiwan lacks the specialized equipment needed for the salvage.
They have hired Global Industries for that.
The divers and equipment are not scheduled to arrive until June 14.
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Time Running Out for Taiwan to Find Crash Black Boxes
TAIPEI (Reuters) - Nearly three weeks after a China Airlines jet crashed mysteriously killing 225 people, Taiwan is running out of time to retrieve the "black boxes" from the ocean floor with signals from them weakening and possibly stopping in days.
Though the location of the cockpit voice and flight data recorders have been known for more than two weeks, officials said on Tuesday choppy seas and strong underwater currents have made it difficult for divers to retrieve them from waters nearly 70 meters (230 feet) deep.
A 23-year-old Hong Kong-bound Boeing 747-200, belonging to Taiwan's largest carrier, broke into four pieces at a height of 30,000 feet (9,000 meters) and fell into the Taiwan Strait near Penghu island some 20 minutes after takeoff on May 25.
The cause of the crash remains a mystery and investigators are hoping the black boxes will help explain what caused it.
Officials said signals from one of the black boxes, which normally last for up to 30 days, had begun to weaken.
Navy divers went underwater again on Tuesday, but strong undercurrents prevented efforts to recover the cockpit voice and flight data recorders.
"Undercurrent is delaying recovery," said Kay Yong, managing director of the Taiwan cabinet's Aviation Safety Council.
"Sometimes, the wind is pretty bad. Wave height is around two to four meters (6.5 to 13 feet)," Yong told Reuters.
"The weather will get worse in the next couple of days."
Salvage teams have instead focused on the retrieval of bodies and wreckage in the choppy seas, but only a fraction of the aircraft has been recovered.
Search teams recovered five more bodies on Monday, bringing to 110 the total number found so far, a spokesman for the government's disaster response center said.
The ill-fated jet's cabin chief was still strapped to his seat when his body was found, puzzling investigators.
Normally, food is served to passengers on Taipei-Hong Kong flights at around 12,000 feet (2,700 meters) because such flights are short and take only 90 minutes, but the cabin chief was still buckled to his seat when the plane broke apart at 30,000 feet, the spokesman said.
Grieving relatives have vented their anger at the government and the airline not only for the carrier's poor safety record and delays in retrieving bodies but also for giving no explanation for what caused the crash.
U.S. crash experts who investigated the mid-air explosion of a Trans World Airlines 747-100 in 1996 are in Taiwan to help determine the cause of China Airlines' fourth fatal accident since 1994 which in total have claimed more than 650 lives.
Aviation experts have floated several theories for the crash, including metal fatigue, an internal explosion, sudden loss of cabin pressure, a mid-air collision or a military accident.
TAIPEI (Reuters) - Nearly three weeks after a China Airlines jet crashed mysteriously killing 225 people, Taiwan is running out of time to retrieve the "black boxes" from the ocean floor with signals from them weakening and possibly stopping in days.
Though the location of the cockpit voice and flight data recorders have been known for more than two weeks, officials said on Tuesday choppy seas and strong underwater currents have made it difficult for divers to retrieve them from waters nearly 70 meters (230 feet) deep.
A 23-year-old Hong Kong-bound Boeing 747-200, belonging to Taiwan's largest carrier, broke into four pieces at a height of 30,000 feet (9,000 meters) and fell into the Taiwan Strait near Penghu island some 20 minutes after takeoff on May 25.
The cause of the crash remains a mystery and investigators are hoping the black boxes will help explain what caused it.
Officials said signals from one of the black boxes, which normally last for up to 30 days, had begun to weaken.
Navy divers went underwater again on Tuesday, but strong undercurrents prevented efforts to recover the cockpit voice and flight data recorders.
"Undercurrent is delaying recovery," said Kay Yong, managing director of the Taiwan cabinet's Aviation Safety Council.
"Sometimes, the wind is pretty bad. Wave height is around two to four meters (6.5 to 13 feet)," Yong told Reuters.
"The weather will get worse in the next couple of days."
Salvage teams have instead focused on the retrieval of bodies and wreckage in the choppy seas, but only a fraction of the aircraft has been recovered.
Search teams recovered five more bodies on Monday, bringing to 110 the total number found so far, a spokesman for the government's disaster response center said.
The ill-fated jet's cabin chief was still strapped to his seat when his body was found, puzzling investigators.
Normally, food is served to passengers on Taipei-Hong Kong flights at around 12,000 feet (2,700 meters) because such flights are short and take only 90 minutes, but the cabin chief was still buckled to his seat when the plane broke apart at 30,000 feet, the spokesman said.
Grieving relatives have vented their anger at the government and the airline not only for the carrier's poor safety record and delays in retrieving bodies but also for giving no explanation for what caused the crash.
U.S. crash experts who investigated the mid-air explosion of a Trans World Airlines 747-100 in 1996 are in Taiwan to help determine the cause of China Airlines' fourth fatal accident since 1994 which in total have claimed more than 650 lives.
Aviation experts have floated several theories for the crash, including metal fatigue, an internal explosion, sudden loss of cabin pressure, a mid-air collision or a military accident.
Moderate, Modest & Mild.
"Aviation experts have floated several theories for the crash, including metal fatigue, an internal explosion, sudden loss of cabin pressure, a mid-air collision or a military accident."................................but still NOT an encounter with severe weather??
Which might help explain why, "The ill-fated jet's cabin chief was still strapped to his seat when his body was found, puzzling investigators.
Which might help explain why, "The ill-fated jet's cabin chief was still strapped to his seat when his body was found, puzzling investigators.
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Excerpted From Aviation Week
Crash Spurs Revamp Of China Airlines
MICHAEL A. DORNHEIM/LOS ANGELES
The search for victims' bodies is occupying the imited recovery resources at the China Airlines Flight 611 crash site, and slowing the retrieval of wreckage and the "black boxes." The flight data
and cockpit voice recorders were located on May 29, but had still not been recovered as of late last week.
Military radar shows debris falling in several different directions, grouped by color, over a 4-min. period (3:27:56 to 3:31:55 p.m.) following loss of the beacon signal (except the dot marked *, which was observed 7 sec. before loss of signal). [Chart omitted]
Investigators are anxious to retrieve them as their beacon batteries may get weak around June 14. Ocean currents and weather also have been hampering recovery from 130-260-ft. depths.
Shortly after the accident, the ASC obtained primary radar data of the falling debris from the military, but it was in a processed form that did not show individual pieces, and it stopped below about 31,000-ft. altitude. The last transponder return indicates the 747 came apart at 33,500 ft. Since then, raw skin returns going down to almost the ocean have been obtained from two civil radars, one
nearby and the other about 150 naut. mi. away.
The new civil data generally confirm the military tracks, which show the debris initially falling in about four different heading groups, including some that are opposite to the airplane's direction, Yong said. But he cautioned that the calculated speed is
questionable because the radar could be hopping between pieces.
China has provided a transponder track to the ASC. It is overall similar to the Taiwanese transponder track with some minor shifts in reported altitude and speed, possibly caused by timing differences. "It shows an altitude dip of 100 meters (330 ft.) 5
sec. before the transponder signal disappears, which we didn't see," Yong said. But neither track shows any rapid maneuvers.
The new skin returns give a more precise location of where pieces hit the ocean. An initial imaging sonar survey shows the major wreckage is in a rectangle about 4 naut. mi. north-south by 5 naut. mi. east-west, surrounding the data recorders, which are at 23 deg. 35 min. N. Lat., 119 deg. 24 min. E. Long. The resolution of the broad search was too low to identify anything, and a higher resolution survey is now being made.
A remote control submersible took pictures of what was suspected to be a large fuselage piece, but it turned out to be a 40 X 10-meter field of smaller debris, including either first- or business-class seats. Most of the recovered wreckage, 454 pieces
as of late last week, has been parts of control surfaces floating on the ocean. These include the vertical stabilizer leading edge and parts of flaps, slats and ailerons.
The year-round ocean current of 2-4 kt. makes underwater operations difficult, and the recovery crew will try to take advantage of roughly half-hour periods when the current stagnates, Yong said. The Taiwan Straits are also windy and choppy.
Maintenance records show that the aircraft, tail No. B18255, had its last full heavy maintenance in December 1993. The D check takes place every 25,000 flight hours and was subsequently split into two staggered "mid-period" half D checks, Yong said. The last mid-period D check took place in January 1999 and included corrosion work, though it is not clear whether that meant prevention or repair. The check was done by CAL during a
40-day period. The 1979-vintage aircraft had about 64,800 hr.
The last C check was done in November 2001. "We can't say yet what was done in the C check, but we're looking at it very carefully," Yong said. The Taiwanese Civil Aeronautics Administration principal maintenance inspector for CAL has been
interviewed, and "we are seeing how they comply with all the airworthiness directives, service bulletins, and so on," he said.
A major maintenance item on 747-200s is ensuring that the "section 41" fuselage nose is not weakened by cracks. This can be accomplished by repetitive inspect-and-repair, or by extensive reinforcement that can cost $5 million. "It seems it
was done from a first look at the records," Yong said, but it was not clear yet whether it was by inspection or reinforcement. "We haven't gotten further because we are short on people." The ASC
will also look at how CAL's other four 747-200s were maintained.
Crash Spurs Revamp Of China Airlines
MICHAEL A. DORNHEIM/LOS ANGELES
The search for victims' bodies is occupying the imited recovery resources at the China Airlines Flight 611 crash site, and slowing the retrieval of wreckage and the "black boxes." The flight data
and cockpit voice recorders were located on May 29, but had still not been recovered as of late last week.
Military radar shows debris falling in several different directions, grouped by color, over a 4-min. period (3:27:56 to 3:31:55 p.m.) following loss of the beacon signal (except the dot marked *, which was observed 7 sec. before loss of signal). [Chart omitted]
Investigators are anxious to retrieve them as their beacon batteries may get weak around June 14. Ocean currents and weather also have been hampering recovery from 130-260-ft. depths.
Shortly after the accident, the ASC obtained primary radar data of the falling debris from the military, but it was in a processed form that did not show individual pieces, and it stopped below about 31,000-ft. altitude. The last transponder return indicates the 747 came apart at 33,500 ft. Since then, raw skin returns going down to almost the ocean have been obtained from two civil radars, one
nearby and the other about 150 naut. mi. away.
The new civil data generally confirm the military tracks, which show the debris initially falling in about four different heading groups, including some that are opposite to the airplane's direction, Yong said. But he cautioned that the calculated speed is
questionable because the radar could be hopping between pieces.
China has provided a transponder track to the ASC. It is overall similar to the Taiwanese transponder track with some minor shifts in reported altitude and speed, possibly caused by timing differences. "It shows an altitude dip of 100 meters (330 ft.) 5
sec. before the transponder signal disappears, which we didn't see," Yong said. But neither track shows any rapid maneuvers.
The new skin returns give a more precise location of where pieces hit the ocean. An initial imaging sonar survey shows the major wreckage is in a rectangle about 4 naut. mi. north-south by 5 naut. mi. east-west, surrounding the data recorders, which are at 23 deg. 35 min. N. Lat., 119 deg. 24 min. E. Long. The resolution of the broad search was too low to identify anything, and a higher resolution survey is now being made.
A remote control submersible took pictures of what was suspected to be a large fuselage piece, but it turned out to be a 40 X 10-meter field of smaller debris, including either first- or business-class seats. Most of the recovered wreckage, 454 pieces
as of late last week, has been parts of control surfaces floating on the ocean. These include the vertical stabilizer leading edge and parts of flaps, slats and ailerons.
The year-round ocean current of 2-4 kt. makes underwater operations difficult, and the recovery crew will try to take advantage of roughly half-hour periods when the current stagnates, Yong said. The Taiwan Straits are also windy and choppy.
Maintenance records show that the aircraft, tail No. B18255, had its last full heavy maintenance in December 1993. The D check takes place every 25,000 flight hours and was subsequently split into two staggered "mid-period" half D checks, Yong said. The last mid-period D check took place in January 1999 and included corrosion work, though it is not clear whether that meant prevention or repair. The check was done by CAL during a
40-day period. The 1979-vintage aircraft had about 64,800 hr.
The last C check was done in November 2001. "We can't say yet what was done in the C check, but we're looking at it very carefully," Yong said. The Taiwanese Civil Aeronautics Administration principal maintenance inspector for CAL has been
interviewed, and "we are seeing how they comply with all the airworthiness directives, service bulletins, and so on," he said.
A major maintenance item on 747-200s is ensuring that the "section 41" fuselage nose is not weakened by cracks. This can be accomplished by repetitive inspect-and-repair, or by extensive reinforcement that can cost $5 million. "It seems it
was done from a first look at the records," Yong said, but it was not clear yet whether it was by inspection or reinforcement. "We haven't gotten further because we are short on people." The ASC
will also look at how CAL's other four 747-200s were maintained.
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Haven't read every post in this thread but had a quick look thru and have found no reference to CAT. Is it not possible that an a/c of this age and condition could break up quite rapidly if it hit a patch of severe CAT?