737-500 missing in Indonesia
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Good write up KG.
Your last comment is wise regarding speculation. Until all relevant information is collected it is wise to be cautious in arriving at an early conclusion.
Your last comment is wise regarding speculation. Until all relevant information is collected it is wise to be cautious in arriving at an early conclusion.
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Hi Folks. Just joined this thread with not having read it all but I have been browsing. There seems to be little doubt that the A/T malfunction was the fault which was the precursor to the crash. Is that correct?
If so, and I apologise if that is not a correct assumption, then the A/T was not the >cause < of the crash.No auto throttle fault (because it not required for dispatch or flight) should be of the least concern to the crew.
Certainly that is my experience of 10,000 plus hours on the 737 all variants (except the MAX) and I would love to fly that of course. No auto-thrust? Set manually. Split thrust - disconnect and set the correct power. One T/L moves when it shouldn't? Put it back and if it doesn't behave, disconnect. So I am not sure where all the discussion about the A/T is going here. Seems that the most likely scenario is that a thrust asymmetry occurred ( given its history on this plane it would have been expected and not a surprise) which would cause the autopilot to put in aileron to counteract the thrust imbalance. [The rudder cannot act in this way so is not involved] This would be blindingly obvious to the pilots because the thrust levers are no longer aligned and the ailerons are displaced. If it wasn't noticed, which seems very strange, then the A/P hits the authority limit at about 25 degrees of aileron and then AP disconnects. A rapid roll would ensue. The remedy is again part of our training ( I am assuming that the people reading this haven't been trained in such a situation) which would be to set symmetrical thrust and roll wings level using full aileron.
I am being lazy here but there are so many pages that I haven't found this mentioned yet. Looking forward to the latest information which must be known by now. The memory card for the VCR? Hard to find in deep water in mud I would think but that is a terrible shame since there lies the complete answer.
If so, and I apologise if that is not a correct assumption, then the A/T was not the >cause < of the crash.No auto throttle fault (because it not required for dispatch or flight) should be of the least concern to the crew.
Certainly that is my experience of 10,000 plus hours on the 737 all variants (except the MAX) and I would love to fly that of course. No auto-thrust? Set manually. Split thrust - disconnect and set the correct power. One T/L moves when it shouldn't? Put it back and if it doesn't behave, disconnect. So I am not sure where all the discussion about the A/T is going here. Seems that the most likely scenario is that a thrust asymmetry occurred ( given its history on this plane it would have been expected and not a surprise) which would cause the autopilot to put in aileron to counteract the thrust imbalance. [The rudder cannot act in this way so is not involved] This would be blindingly obvious to the pilots because the thrust levers are no longer aligned and the ailerons are displaced. If it wasn't noticed, which seems very strange, then the A/P hits the authority limit at about 25 degrees of aileron and then AP disconnects. A rapid roll would ensue. The remedy is again part of our training ( I am assuming that the people reading this haven't been trained in such a situation) which would be to set symmetrical thrust and roll wings level using full aileron.
I am being lazy here but there are so many pages that I haven't found this mentioned yet. Looking forward to the latest information which must be known by now. The memory card for the VCR? Hard to find in deep water in mud I would think but that is a terrible shame since there lies the complete answer.
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Hi,
When the media are talking about the search of the "memory card", "memory unit" or "memory module" of the CVR, do they mean that barrel-shaped, armored steel capsule that is, by volume, several times the size of the already found pinger?
Or do they actually mean smaller parts that have somehow gotten out of their protective container during the crash?
When the media are talking about the search of the "memory card", "memory unit" or "memory module" of the CVR, do they mean that barrel-shaped, armored steel capsule that is, by volume, several times the size of the already found pinger?
Or do they actually mean smaller parts that have somehow gotten out of their protective container during the crash?
Safety of the divers is very important when working in all kinds of weather. Continued searches likely need additional equipment. It takes time to sort out what equipment exists and is available on short notice. Meanwhile you standdown part of the investigating team and reorganize later. Some of the landlubbers get sick while bobbing in flat bottom boats at sea for days
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M68
There is a picture posted many pages back that shows the pinger and the destroyed remains of the CVR. The memory module is not there. There are 2 pingers, the destroyed remains and the FDR in the box.
There is a picture posted many pages back that shows the pinger and the destroyed remains of the CVR. The memory module is not there. There are 2 pingers, the destroyed remains and the FDR in the box.
Last edited by hunbet; 31st Jan 2021 at 20:17. Reason: Add pictur
How on earth did you come to that conclusion?
Everything is on the table so far.
There seems to be little doubt that the A/T malfunction was the fault which was the precursor to the crash. Is that
Everything is on the table so far.
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Hi Icarus2001. I did say it as a question because as I said I am new to this thread. I said. >>> Is that correct?
If so, and I apologise if that is not a correct assumption? However I have been reading the the subject aircraft had been suffering AT problems for a few days and here is REUTERS a couple of days ago but it has been in many other reliable journals. Of course the Indonesian AAIB will have that information and a 30 day report should be out soon. Indonesia probing whether faulty system contributed to Sriwijaya Air crashAgustinus Beo Da CostaJAKARTA (Reuters) - Indonesia’s air accident investigator is probing whether a problem with the autothrottle system, that controls engine power automatically, contributed to the Sriwijaya Air crash on Jan. 9 that killed all 62 people on board, an official said on Friday.
National Transportation Safety Committee (KNKT) investigator Nurcayho Utomo said a problem with the Boeing 737-500’s autothrottle system was reported after a flight a few days earlier.
“There was a report of malfunction on the autothrottle a couple of days before to the technician in the maintenance log, but we do not know what kind of problem,” he told Reuters. “If we find the CVR (cockpit voice recorder) we can hear the discussion between the pilots, what they talked about and we will know what is the problem.”
It remains unclear whether a problem with the autothrottle system contributed to the crash, Utomo said, adding he could not recall any other issues raised in the maintenance log.
It is acceptable for a plane to fly with an autothrottle system that is not working because pilots can control it manually instead, he said.
Sriwijaya said he was unable to comment on technical matters involving the investigation before an official statement was made by KNKT. A preliminary report is expected to be issued within 30 days of the crash, in line with international standards.
The plane’s flight data recorder (FDR) has been recovered and read by investigators but an underwater search for the CVR’s memory unit at the crash site in the Java Sea is continuing.
Citing sources close to the investigation, the Wall Street Journal (WSJ) on Thursday reported the FDR data showed the autothrottle system was not operating properly on one of the plane’s engines as it climbed on departure from Jakarta.
Instead of shutting off the system, the FDR indicated the pilots tried to get the stuck throttle to function, the WSJ said. That could create significant differences in power between engines, making the jet harder to control.
If so, and I apologise if that is not a correct assumption? However I have been reading the the subject aircraft had been suffering AT problems for a few days and here is REUTERS a couple of days ago but it has been in many other reliable journals. Of course the Indonesian AAIB will have that information and a 30 day report should be out soon. Indonesia probing whether faulty system contributed to Sriwijaya Air crashAgustinus Beo Da CostaJAKARTA (Reuters) - Indonesia’s air accident investigator is probing whether a problem with the autothrottle system, that controls engine power automatically, contributed to the Sriwijaya Air crash on Jan. 9 that killed all 62 people on board, an official said on Friday.
National Transportation Safety Committee (KNKT) investigator Nurcayho Utomo said a problem with the Boeing 737-500’s autothrottle system was reported after a flight a few days earlier.
“There was a report of malfunction on the autothrottle a couple of days before to the technician in the maintenance log, but we do not know what kind of problem,” he told Reuters. “If we find the CVR (cockpit voice recorder) we can hear the discussion between the pilots, what they talked about and we will know what is the problem.”
It remains unclear whether a problem with the autothrottle system contributed to the crash, Utomo said, adding he could not recall any other issues raised in the maintenance log.
It is acceptable for a plane to fly with an autothrottle system that is not working because pilots can control it manually instead, he said.
Sriwijaya said he was unable to comment on technical matters involving the investigation before an official statement was made by KNKT. A preliminary report is expected to be issued within 30 days of the crash, in line with international standards.
The plane’s flight data recorder (FDR) has been recovered and read by investigators but an underwater search for the CVR’s memory unit at the crash site in the Java Sea is continuing.
Citing sources close to the investigation, the Wall Street Journal (WSJ) on Thursday reported the FDR data showed the autothrottle system was not operating properly on one of the plane’s engines as it climbed on departure from Jakarta.
Instead of shutting off the system, the FDR indicated the pilots tried to get the stuck throttle to function, the WSJ said. That could create significant differences in power between engines, making the jet harder to control.
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If there was a tech log entry for the A/T system the engineers should have carried out the required tests, for those of you with interest they can be seen on the video here:
https://www.sjap.nl/?s=autothrottle
In any event, a failed A/T should not be a reason to crash, presuming the pilots are " in the loop" and competent to diagnose and apply the appropriate actions, the QRH directs the pilots to the most appropriate actions: Re-engage or Disconnect. Taking actions outside of the manufactures guidance is not advised, however, again we are in the realms of speculation, and in this part of the world when anyone says a "source close to" take it with a very large pinch of salt.
https://www.sjap.nl/?s=autothrottle
In any event, a failed A/T should not be a reason to crash, presuming the pilots are " in the loop" and competent to diagnose and apply the appropriate actions, the QRH directs the pilots to the most appropriate actions: Re-engage or Disconnect. Taking actions outside of the manufactures guidance is not advised, however, again we are in the realms of speculation, and in this part of the world when anyone says a "source close to" take it with a very large pinch of salt.
Without the CVR, what output to the DFDR would confirm what the pilots were doing to the auto-throttle? Is it not possible that the pilots showed no recognition nor took any action until an upset?
The DFDR should have throttle position - if it splits with the autothrottle on, that would be pretty good indication that a clutch was slipping, if that split persists it would similarly be a good indication that the crew wasn't addressing the problem (or, in the case of a seized throttle, was unable to address).
They're going to need the CVR to understand the why.
BTW, it would be pretty much unheard of for the memory module to come out of it's protective steel (or titanium) protective shell. I can't tell much from the photo above, but I suspect the protective shell separated from the rest of the CVR module - it's that protective shell they need to find. If it's steel, they may be able to use a magnetic anomaly indication to help locate it.
They're going to need the CVR to understand the why.
BTW, it would be pretty much unheard of for the memory module to come out of it's protective steel (or titanium) protective shell. I can't tell much from the photo above, but I suspect the protective shell separated from the rest of the CVR module - it's that protective shell they need to find. If it's steel, they may be able to use a magnetic anomaly indication to help locate it.
Parts sent to the US and GB (Reuters)
"Indonesia’s air accident investigator has sent five components of a crashed Sriwijaya Air jet to the United States and Britain for examination, including the autothrottle that controls engine power automatically, the agency’s head said on Tuesday."
"Indonesia’s air accident investigator has sent five components of a crashed Sriwijaya Air jet to the United States and Britain for examination, including the autothrottle that controls engine power automatically, the agency’s head said on Tuesday."
Am I being simplistic, but why on earth should any A/T malfunction/ unserviceability cause any aircraft to crash? All aircraft are cleared to fly with the A/T u\s. On my last type we could even carry out CATIII autolands manipulating the Thrust Levers manually.
On first sign of malfunction when airborne, disconnect and operate the Thrust Levers manually as normal. Even if required, possibly disconnect the autopilot and fly manually while you sort out the automatics. Or am I missing something?
On first sign of malfunction when airborne, disconnect and operate the Thrust Levers manually as normal. Even if required, possibly disconnect the autopilot and fly manually while you sort out the automatics. Or am I missing something?
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On 2021.02.01 Chairman of the KNKT Soerjanto Tjahjono announced that search operations for the CVR resumed after being suspended for 3-4 days due to bad weather & high waves.
From a translation, it appears teams of three divers are inspecting 5M x 5M sections of a grid pattern for twenty minute intervals before moving to a fresh section.
From a translation, it appears teams of three divers are inspecting 5M x 5M sections of a grid pattern for twenty minute intervals before moving to a fresh section.
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If you are referring to the PS3 sense pressure line, there can be loss of "automatic thrust control" as the FCU will attempt to adjust the fuel flow and hence shaft speed to the Thrust lever position, however, as the CDP (compressor discharge pressure or PS3) is an element required by the FCU To adjust the calculated fuel flow to the current air density at the combustor inlet, the FCU needs at least the inputs of the compressor inlet temperature (CIT AND the compressor discharge pressure (CDP or Ps3) additionally to the N2 speed and the power lever input.
If the inputs are not available there is a potential for the engine to either operate outside the surge limits or flame out limits, in which case the crew would need to carry out the associated QRH or recall (memory items) and either operate with the engine shut down or manage within the limits (surge only).
Another video here for the tech heads!
If the inputs are not available there is a potential for the engine to either operate outside the surge limits or flame out limits, in which case the crew would need to carry out the associated QRH or recall (memory items) and either operate with the engine shut down or manage within the limits (surge only).
Another video here for the tech heads!
EPR increases while N1 remains stable. Read the Swiftair MD-83 accident report for full details: https://reports.aviation-safety.net/...D83_EC-LTV.pdf
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"EPR increases while N1 remains stable. Read the Swiftair MD-83 accident report for full details: https://reports.aviation-safety.net/...D83_EC-LTV.pdf"
I think Nik was referring to the P3 pressure pipe on the engine not the P2 sensor on the nose cone
I think Nik was referring to the P3 pressure pipe on the engine not the P2 sensor on the nose cone