Ethiopian airliner down in Africa
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Clearly you have never left the US and are not familiar with the various forms of noise abatement procedures used worldwide. Google NADP2 (Proc B) and you'll understand most non-US carriers worldwide routinely accelerate and commence flap retraction at >800' (NADP2) or >1000' (Proc B) above 1000' AFE.
Noise Abatement Procedures
Last edited by Dune; 13th Mar 2019 at 05:35.
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Don't get me wrong, I totally agree. The 737 should stop at 150 people and 3 hours, (if B wants a bigger plane start building the 757NG.) If you have stretched your plane so far you need an extra telescoping landing gear and higher speeds to prevent a tailstrike, and software trimming because of inherent instability you are doing something wrong. If you implement said band-aid with a single source input and call it a day, you are well on your way to criminal negligence. MCAS should never have been designed, build or approved this way, my post was just a reply to someone who was more scared of software than hardware, and I disagreed with his POV.
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Clearly you have never left the US and are not familiar with the various forms of ICAO noise abatement procedures. Google NADP1 vs NADP2 and you'll understand most non-US carriers worldwide routinely accelerate and commence flap retraction (NADP2) above 1000' AFE.
http://www.b737mrg.net/downloads/b737mrg_noise.pdf
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What does the data say?
Non-pilot but expert number cruncher with a basic questions about the DATA shown in post 69 and several prior to that.
Looking at the ADS-B numbers, in ascending time sequence from the start of the takeoff roll at 05:38:01Z, I see:
18 seconds with 0 elevation gain (to 7,200') and acceleration from 0 to 93 knots (ETH-302 still on the runway?)
5 seconds with 25' elevation gain (to 7,225') and acceleration from 93 to 105 knots (ETH-302 still on the runway?)
11 seconds with 00' elevation gain (to 7,225') and acceleration from 105 to 154 knots
11 seconds with 25' elevation LOSS (to 7,200') and acceleration from 154 to 183 knots (did ETH-402 try to lift off runway and then settle back on to it?)
14 seconds with 25' elevation gain (to 7,225') and acceleration from 183 to 200 knots
59-seconds after beginning the takeoff roll - the plane was at 200-knots and had gained NO altitude above the runway (based on elevation at 105-knots). Is that possible?
At 59-seconds there could not be much of the ~12,465' runway left ahead of the plane since it had been doing an average of 150-knots (250 fps) for 33-seconds (8,250') and had travelled about 3,000' accelerating in the first 26-seconds.. At what point would the takeoff be rejected? Or is this just a normal takeoff at a hot and high airport?
I assume MCAS could not have been active during the first 60-seconds of the takeoff event.
Continuing with the sequential timestamps:
50-seconds with 925' elevation gain (to 8,150') and acceleration from 200 to 263 knots.
25-seconds with 450' elevation LOSS (to 7,700') and acceleration from 263 to 323 knots.
45-seconds with 900' elevation gain (to 8,609') and acceleration from 323 to 283 knots.
From the time ET-402 reached 226-knots at 7,575' there were 33 ADS-B reports of which only 7 showed a loss of altitude and they all occurred in a 21-second period (5:39:55 to 5:40:16)
During the period 5:40:09 to 5:40:45 the plane maintained an altitude of 7,750' +25'/-50'.
From 5:40:35 to 5:41:02 (end of data) the plane climbed steadily and gained 875' while accelerating to 383-knots.
How does the data above fit with the theory of MCAS forcing a rapid descent?
Looking at the ADS-B numbers, in ascending time sequence from the start of the takeoff roll at 05:38:01Z, I see:
18 seconds with 0 elevation gain (to 7,200') and acceleration from 0 to 93 knots (ETH-302 still on the runway?)
5 seconds with 25' elevation gain (to 7,225') and acceleration from 93 to 105 knots (ETH-302 still on the runway?)
11 seconds with 00' elevation gain (to 7,225') and acceleration from 105 to 154 knots
11 seconds with 25' elevation LOSS (to 7,200') and acceleration from 154 to 183 knots (did ETH-402 try to lift off runway and then settle back on to it?)
14 seconds with 25' elevation gain (to 7,225') and acceleration from 183 to 200 knots
59-seconds after beginning the takeoff roll - the plane was at 200-knots and had gained NO altitude above the runway (based on elevation at 105-knots). Is that possible?
At 59-seconds there could not be much of the ~12,465' runway left ahead of the plane since it had been doing an average of 150-knots (250 fps) for 33-seconds (8,250') and had travelled about 3,000' accelerating in the first 26-seconds.. At what point would the takeoff be rejected? Or is this just a normal takeoff at a hot and high airport?
I assume MCAS could not have been active during the first 60-seconds of the takeoff event.
Continuing with the sequential timestamps:
50-seconds with 925' elevation gain (to 8,150') and acceleration from 200 to 263 knots.
25-seconds with 450' elevation LOSS (to 7,700') and acceleration from 263 to 323 knots.
45-seconds with 900' elevation gain (to 8,609') and acceleration from 323 to 283 knots.
From the time ET-402 reached 226-knots at 7,575' there were 33 ADS-B reports of which only 7 showed a loss of altitude and they all occurred in a 21-second period (5:39:55 to 5:40:16)
During the period 5:40:09 to 5:40:45 the plane maintained an altitude of 7,750' +25'/-50'.
From 5:40:35 to 5:41:02 (end of data) the plane climbed steadily and gained 875' while accelerating to 383-knots.
How does the data above fit with the theory of MCAS forcing a rapid descent?
Sorry to disappoint you, but I have 5 type ratings, 10K+ hours, FAA ATP & JAA ATPL.
And as explained more clearly below MCAS has nothing to do with thrust, and everything with aerodynamics.
I suggest you read it, and let me know if you need any more help becoming less condescending.
Hans - your patience is amazing. You are correct about the relationship between 737MAX engines and need for MCAS. It has nothing to do with the thrust pitching moment!!!
There is a cert requirement that as AOA increases, the nose up pilot command required must not decrease. This is demonstrated at fixed thrust levels so there is no change in thrust pitching moment. The 737MAX issue here that gives rise to the need for MCAS is that as AOA increases the lift provided by the engine cowling that is so large and mounted so far forward of the wing causes a nose up pitching moment that results is a decrease in the column pull needed to maintain a steady positive AOA rate. That characteristic is not compliant with the requirements. MCAS comes active during this maneuver putting in nose down stabilizer that must be countered by the column. The net effect of engine cowling lift and MCAS nose down stabilizer as AOA increases is that the column needed to complete the maneuver does not decrease part way through the range of AOA for which characteristics must be demonstrated. 737MAX without MCAS fails the cert demo. 737MAX with MCAS passes the cert demo.
There is a cert requirement that as AOA increases, the nose up pilot command required must not decrease. This is demonstrated at fixed thrust levels so there is no change in thrust pitching moment. The 737MAX issue here that gives rise to the need for MCAS is that as AOA increases the lift provided by the engine cowling that is so large and mounted so far forward of the wing causes a nose up pitching moment that results is a decrease in the column pull needed to maintain a steady positive AOA rate. That characteristic is not compliant with the requirements. MCAS comes active during this maneuver putting in nose down stabilizer that must be countered by the column. The net effect of engine cowling lift and MCAS nose down stabilizer as AOA increases is that the column needed to complete the maneuver does not decrease part way through the range of AOA for which characteristics must be demonstrated. 737MAX without MCAS fails the cert demo. 737MAX with MCAS passes the cert demo.
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We don't know about Ethiopian, but I am convinced Lion Air is directly caused by faulty AOA info to MCAS. Should the pilots have been able to recover like the ones did the day before? Probably/absolutely, but that doesn't change that the MCAS design is a major problem.
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Well, while not exactly the same, I guess you think they better dump the 777-300ER as well due to the design features needed on that jet??
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MCAS event could happen at any phase of flight. You just need: a failed AoA sensor, AP disengaged (would failed AoA disengage AP?) and flaps up.
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Tacoma Sailor....How does the data above fit with the theory of MCAS forcing a rapid descent?
This data may not fit any theory yet, but there is fairly solid evidence of a rapid descent.
There is a large crater with small bits of 737Max in it.
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And that, ladies and gentlemen, is complete bull****. Porsche only built the 911 from 1963 until 1989. The model that is sold today under the marketing designation 911 has zero commonality (other than styling and marketing) with the actual model 911, very much unlike the 737 MAX.
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Time frame for CVR and data recorder analysis
I am a non professional, so grateful for any insight regarding recorder analysis. If the recorders are in a reasonable condition, I presume down loading data is like down loading from a massive USB stick. This surely must have already be done by now? As it seems that the cockpit crew were able to communicate with the tower, so there must have also been some crucial conversation between captain and first officer as well. That voice recording could quite quickly tell us what they thought was going on. What I am really asking i suppose, is how quickly, are we likely to hear a preliminary report of what happened to aircraft. For an example, if there was a terrorist saying, " i will blow up this plane", surely Boeing would release this information ASAP. However, if the voice clearly points to a stall system fault, would they be as quick to release their preliminary findings ?
AoA Sensor
So the AoA Sensor is usually a pretty rugged piece of kit.
What could cause it to fail?
Either the output has an anomaly (electrical/electronic side) or there is a mechanical problem (vane stuck).
What could cause a vane to stick?
Fine sand? Volcanic ash?
Where did this happen?
What could cause it to fail?
Either the output has an anomaly (electrical/electronic side) or there is a mechanical problem (vane stuck).
What could cause a vane to stick?
Fine sand? Volcanic ash?
Where did this happen?
at least those pilots who saved the previous pk-lqp Dps-cgk lion air won against Mcas accident, without knowing Mcas even existed and stick shaker blaring all along flight.
as a pax, are these pilots that could handle this situation are rare or not ?
if not then Boeing should really re examined their mcas, and aoa parts should be on MEL.
But could whole AOA system tested on ground ?
The cheese happened to line up for the crash crew; bad day, sub standard, no sleep, ex wife giving grief, fo thinking about his upcoming tinder date...
sometimes it just all comes together, sadly.
One big read button on the yoke that disables ALL automatic functions, including MCAS!
I don’t fly the 737, but the regional airliner I have flown for the last 20 years gives total control to the pilot once this button is pushed. Not even the yaw damper is retained. I mean Jesus H Christ! What the hell has happened to simple common sense in design?