737-500 missing in Indonesia
Too many times you see crews failing to nail a simple request like "approximately 40%", will not wait for the engines to react and push even more forward asking 60-70%.
We also see PM's who "back up" the thrust levers as they move under TOGA and then for some reaon keep their hand behind the thrust levers while the PF has his hand on the thust levers. Old Wives Tales again from DC3 era about throttles and dodgy friction nuts. if the PF suddenyly chops the throttles to abort, the PM is in danger of severely damaging his hand caught between the aft edge of the throttles and the start levers in the 737.
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According to KNKT, the flight data recorder (FDR) was filled with 370 flight parameters from 27-hour flight recording, which is in total 18 flights that include its tragic final flight.
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In my two posts on 11.1.21, which were deleted for some reason, I stated (in my opinion as someone who has worked on various aspects of aircraft safety) that the CG position on SJ-182 could be “marginal...too far forward”, but that a trigger event such as “a throttle back” would be needed in order for a sudden pitch down ‘incident’ to occur. An auto-throttle fault could be just such a trigger; the CG problem would worsen and the situation could be unrecoverable.
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Amazing how some people here seems always to know better without even knowing the details of the event. I have many PIC hours on the 737 so I am not your newbie you can teach on a forum on how to fly, It was easy to recognize and correct. But it can happen. It also happened on initial approach before LOC capture nowhere near final (that's your wrong assumption) and the hand was on the MCP for just few seconds, enough to develop some asymmetric thrust that was then quickly corrected. Not saying that this is what happened here, just saying that it can happen to anyone.
VicMel As someone who did load control on just about every 737 variant built, I can say with some degree of confidence that you have to work really-really hard to get a -500 out of forward CG limits. Should this happen, the first thing the pilots will notice is that it will refuse to rotate after the Vr call.
Last edited by andrasz; 20th Jan 2021 at 08:36.
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Yes I think he did , but even VR, that did not prevent aircraft from trying to take off before , albeit sometimes scrapping the tail but generally managing to get airborne. and none resulted in an accident.( western passenger aircraft that is ) so not really relevant here I would say.
MCP = Mode Control Panel. (In Airbus world it’s called the FCU - Flight Control Unit.) In either case it’s the centre instrument panel mounted on the glareshield. It’s where the flight path controls are located - heading, height, speed, flight directors, autothrottle, autopilot etc.
Last edited by Bleve; 19th Jan 2021 at 23:02.
Couldn't agree more. Seen that in 80% of simulator sessions in the 737. Just as illogiocal are those who overshoot the approximately 40% N1 advice during the rolling start, then hurriedly reduce power back to approx 40% N1 when they realise what has happend and then shove open to takeoff power hitting TOGA on the way, oblivious to the fact that they are eating up runway distance and invalidating V1 in some cases.
that is a natural response to the way we do an evaluation of crew performance. it is a measurable "error" that an instructor or examiner can comment on, so commentary on that and a consequential irrational emphasis can result. The problem of being human. Institutional training devolves over time towards a firm grasp on the trivial, unless an independent review of system behavior occurs.
As you describe, the outcome from an excessive concentration on a specific value rather than the underlying reason for a value, (achieving near symmetric acceleration of the engines results in a loss of SA on the equally serious matter of achieving takeoff performance. it's a good example of consequences, as was the overemphasis on automation use which led to loss of skills and more importantly, loss of SA of many crews reliant on automation.
We also see PM's who "back up" the thrust levers as they move under TOGA and then for some reaon keep their hand behind the thrust levers while the PF has his hand on the thust levers. Old Wives Tales again from DC3 era about throttles and dodgy friction nuts. if the PF suddenyly chops the throttles to abort, the PM is in danger of severely damaging his hand caught between the aft edge of the throttles and the start levers in the 737.
VicMel
ANDRASZ's answer covers this matter as being remote. My own flight testing on the -500, we were required to do baseline stalls of the aircraft at its limit cases, fore, and aft, at high and low weights. Those we had to meet by having a couple of tons of drinking water from Sams Club and moving from aft hold to forward hold, we also had movable ballast inside the aircraft so that the TO and LDG were done within the basic envelope of the aircraft. longitudinal stability was adequate at all times. The only notable curiosity in the plane was a clean stall where the slat rigging could result in a minor amount of roll but it was a non-event.
On the autothrottle musings, the info available so far doesn't match well to a thrust change occurring leading to a yaw/roll/APLT disc/uncommanded open-loop roll departure. it is a simple scenario, but with a relatively steady state before the upset, a thrust change is not evident. That may be the data granularity, or the scenario doesn't fit. It is unlikely that the asymmetry was there for minutes undetected, so a change in rates immediately before the upset would be expected in the ATR clutch scenario, and that doesn't seem to be there.
ANDRASZ's answer covers this matter as being remote. My own flight testing on the -500, we were required to do baseline stalls of the aircraft at its limit cases, fore, and aft, at high and low weights. Those we had to meet by having a couple of tons of drinking water from Sams Club and moving from aft hold to forward hold, we also had movable ballast inside the aircraft so that the TO and LDG were done within the basic envelope of the aircraft. longitudinal stability was adequate at all times. The only notable curiosity in the plane was a clean stall where the slat rigging could result in a minor amount of roll but it was a non-event.
On the autothrottle musings, the info available so far doesn't match well to a thrust change occurring leading to a yaw/roll/APLT disc/uncommanded open-loop roll departure. it is a simple scenario, but with a relatively steady state before the upset, a thrust change is not evident. That may be the data granularity, or the scenario doesn't fit. It is unlikely that the asymmetry was there for minutes undetected, so a change in rates immediately before the upset would be expected in the ATR clutch scenario, and that doesn't seem to be there.
The aircraft track shows 10 seconds of an absolutely level LH turn from the departure track of 045° onto 015°, followed by a further 10 seconds of continuing but descending LH turn onto about 340°, before starting the 12 second RH spiral descent which continued all the way to impact.
[insert compatible scenario here]
[insert compatible scenario here]
AvHerald:
The KNKT have already developed a general picture of the accident, however, need further data from the cockpit voice recorder before publishing any information. Inspections of Boeing 737-300, 737-400 and 737-500 in Indonesia have been ordered.
A first hint that Technical Causes played a role.
The KNKT have already developed a general picture of the accident, however, need further data from the cockpit voice recorder before publishing any information. Inspections of Boeing 737-300, 737-400 and 737-500 in Indonesia have been ordered.
A first hint that Technical Causes played a role.
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Not necessarily
“In the letter signed by the Executive Director of Airworthiness and Aircraft Operations Udi Tito Priyatna, DKPPU will conduct an examination of 7 main aspects, namely:
– Implementation of the airworthiness directive (AS) compliance
– Carrying out routine inspections and major inspections
– Repetitive monitoring
– Implementation of pilot training
– Implementation of a pilot professional check
– Crew duty time”
http://netral.news/en/ministry-of-tr...indonesia.html
“In the letter signed by the Executive Director of Airworthiness and Aircraft Operations Udi Tito Priyatna, DKPPU will conduct an examination of 7 main aspects, namely:
– Implementation of the airworthiness directive (AS) compliance
– Carrying out routine inspections and major inspections
– Repetitive monitoring
– Implementation of pilot training
– Implementation of a pilot professional check
– Crew duty time”
http://netral.news/en/ministry-of-tr...indonesia.html
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You left out the important line above:
“... starting January 11, 2021,” quoted from the letter obtained by Kompas.com, Monday (11/1/2021)."
This is all old news from the time before the FDR was even found - let alone downloaded. At this point, they basically had no facts about the accident and thus triggered the most generic news release - basically saying they will look into everything (maintenance, ADs, pilots, training, ...). No surprises there.
It'd be more interesting to know what actions they decided to trigger after the FDR was found (12/1/2021) and after its data is downloaded (13/1/2021)...
“... starting January 11, 2021,” quoted from the letter obtained by Kompas.com, Monday (11/1/2021)."
This is all old news from the time before the FDR was even found - let alone downloaded. At this point, they basically had no facts about the accident and thus triggered the most generic news release - basically saying they will look into everything (maintenance, ADs, pilots, training, ...). No surprises there.
It'd be more interesting to know what actions they decided to trigger after the FDR was found (12/1/2021) and after its data is downloaded (13/1/2021)...