b747-100..JAL123 ACCIDENT
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b747-100..JAL123 ACCIDENT
Recently watch a late evening programme on PBS of `Aircraft Accidents Recreated` where guest pilots are given an accident scenario ,and try to recreate the outcome,and later try to resolve it to a safe result,in a `simulator`.In the JAL 123 accident ,after the decompression and loss of fin and rudder,and hydraulics,no mention is made of attempting to use the trim system to move the stabiliser in pitch to control the phugoid motion.? Is the stabiliser `jack` a screw jack,electrically powered ,or electro-hydraulic powered,and unable to move...? Is it physically possible to move the ailerons with no fluid..? How are the LE Slats operated...? in conjunction with the flaps...?
Overall ,a tragic accident,and in retrospect the cockpit crew should have been on oxygen as soon as possible.
I put it here ,as the quality of answers are usually best...
Overall ,a tragic accident,and in retrospect the cockpit crew should have been on oxygen as soon as possible.
I put it here ,as the quality of answers are usually best...
Recently watch a late evening programme on PBS of `Aircraft Accidents Recreated` where guest pilots are given an accident scenario ,and try to recreate the outcome,and later try to resolve it to a safe result,in a `simulator`.In the JAL 123 accident ,after the decompression and loss of fin and rudder,and hydraulics,no mention is made of attempting to use the trim system to move the stabiliser in pitch to control the phugoid motion.? Is the stabiliser `jack` a screw jack,electrically powered ,or electro-hydraulic powered,and unable to move...? Is it physically possible to move the ailerons with no fluid..? How are the LE Slats operated...? in conjunction with the flaps...?
Overall ,a tragic accident,and in retrospect the cockpit crew should have been on oxygen as soon as possible.
I put it here ,as the quality of answers is usually best...
Overall ,a tragic accident,and in retrospect the cockpit crew should have been on oxygen as soon as possible.
I put it here ,as the quality of answers is usually best...
The phugoid was quite a substantial amplitude, but at the same time the directional stability had been compromised, they did amazingly well to keep it in the air as long as they did. UAL 232 had similar phugoids that the crew had to try and compensate for, as all aircraft have. The B777 and B787 even being FBW have a phugoid that is quite gentle and damped, but is a slight surprise for a FBW aircraft. The Airbus ( "C*" logic) FBW doesn't look at the Speed trim function U in the pitch mode, Boeing ("C*U") does so it naturally gets a phugoid as a gift. Makes the Airbus a bit nicer in pitch to fly normally. When stuff goes wrong, the reversion requires manual trim and that too often gets overlooked in all of the entertainment. Seem to recall the control process was a PI design, the PID doesn't always work well with humans in the loop. Could be wrong, PID or PLC works well for full auto light systems that don't have to deal with human delays and gain issues.
Last edited by fdr; 11th Jul 2022 at 16:01.
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Some interesting comments about the rescue(possibly assuming all must have died.....
"The japanese military took 14 hours to arrive to the crash site, which caused more deaths that could've been saved if they arrived faster, the 4 survivors said they were able to hear many people screaming all night in the forest. I can't imagine how terrifying that must've felt"
"Very True, the US military was first to arrive but were called back by the Japanese Authorities. ️ They even radioed a signal to the Japanese and a nearby air base. I’m not sure how management was like back then but wow. I’m shocked by this delay. If only authorities didn’t call back the US military. Refusing help in moments like this is a BIG Mistake."
"The Marines had scrambled a medevac to help survivors and were there within an hour iirc. The Japanese government demanded that the Marines be recalled."
"For all their successes, Japanese authorities can have serious bouts of incompetence and xenophobic arrogance especially when foreigners (Gaijin) are involved. It was pure arrogance rejecting the help of the USMC on that day. It was also a contributing factor to the Fukushima disaster, when the plant was designed and American GE engineers pointed out that the backup generators were at risk of flooding, the Japanese management ignored them."
