Ethiopian airliner down in Africa
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What is the source for the above statement? There is no information in the current B738M AOM that tells crews that the "MCAS cycles between the left AoA and the right AoA sensor".
Some rough working assumptions (probably overly optimistic):
350 aircraft
In service for 2 years, each aircraft available 340 days/yr, 5 sectors/day.
Total number of departures: approx 1.2m giving a fatal accident rate of 1.67 per million flights.
In comparison using figures up to 2017:
Banderantie - 3.07. (Ouch!)
Concorde - 11.36 (indicative of very low numbers in service and utilisation)
F28 - 1.65
A310 - 1.34
B747 (early models) 1.02
B747 (-400 onwards) - 0.06
B737 (all models) - 0.28
A320 series - 0.11
350 aircraft
In service for 2 years, each aircraft available 340 days/yr, 5 sectors/day.
Total number of departures: approx 1.2m giving a fatal accident rate of 1.67 per million flights.
In comparison using figures up to 2017:
Banderantie - 3.07. (Ouch!)
Concorde - 11.36 (indicative of very low numbers in service and utilisation)
F28 - 1.65
A310 - 1.34
B747 (early models) 1.02
B747 (-400 onwards) - 0.06
B737 (all models) - 0.28
A320 series - 0.11
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https://www.reuters.com/article/ethi...-idUSL1N20Z01K
Just wow... Begs the question, how long have they known about the issues???
Was the aircraft pushed out too early to "meet schedule" and increase profit?
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This is correct. MCAS is implemented within the two Flight Control Computers (FCCs). The Left FCC uses the Left AOA sensor for MCAS and the Right FCC uses the Right AOA sensor for MCAS. Only one FCC operates at a time to provide MCAS commands. With electrical power to the FCCs maintained, the unit that provides MCAS changes between flights. In this manner, the AOA sensor that is used for MCAS changes with each flight.
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This still will not prevent an urgent or quick movement of the switches to the OFF position if necessary.
From B707's, B727 & B747 all the same where in the event of a runaway stabilizer (or serious Nose Up\Down Stab trimming) the procedure was/is to switch the Stab Trim off and revert to Manual trim.
Instilled into me when flying these types and exercises practiced in simulator form time to time.
Would have thought this would have summed all up and provided operations Departments and Pilots with fairly clear instructions?
From B707's, B727 & B747 all the same where in the event of a runaway stabilizer (or serious Nose Up\Down Stab trimming) the procedure was/is to switch the Stab Trim off and revert to Manual trim.
Instilled into me when flying these types and exercises practiced in simulator form time to time.
Would have thought this would have summed all up and provided operations Departments and Pilots with fairly clear instructions?
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We are all keenly interested in what the FDR and CVR will show from this second accident.
Either they will show:
Either they will show:
- a similar scenario as Lion or
- something different.
IF it has occurred again, AND the crew haven't done the checklist, then we really should be looking at pilot training. However, despite conclusions that many are jumping to here, we should be awaiting the CVR and FDR outcome because this has the potential to be one of many scenarios.
Last edited by greenfields; 12th Mar 2019 at 07:02.
(Top right above) Quote: "Pilots are reminded that an erroneous AOA can cause some or all of the following indications and effects."
How calm would you need to be, and long would you need to sort out all of those?
So, not only erroneous AOA sensors can set off MCAS.
How calm would you need to be, and long would you need to sort out all of those?
So, not only erroneous AOA sensors can set off MCAS.
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Really? I'll admit to being wrong, but can you give some examples? I've done a small bit of traveling around Western and Eastern Europe (France, England, Bulgaria), and I don't remember anything about the light switches, and I feel like it would stick out in my memory as a shocking adjustment had they been down=on.
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737 pilot here.
What concerns me, is that many people are saying “I’d just set Power and Pitch, I’d notice if the aircraft was trimming against me, and move the STAB TRIM CUTOUT switches” Which, following the Lion Air accident, was exactly what I was thinking.
However, if this accident also turns out to be MCAS related, do we need to explore the possibility that the MCAS operation in flight, combined with the possibility of Airspeed Unreliable, Stall Warning, Possible Windshear alerts, is much more violent and hard to control than we initially thought?
Two sets of pilots can’t deal with it- is my aircraft actually flyable under these conditions 1000ft above the ground?
What concerns me, is that many people are saying “I’d just set Power and Pitch, I’d notice if the aircraft was trimming against me, and move the STAB TRIM CUTOUT switches” Which, following the Lion Air accident, was exactly what I was thinking.
However, if this accident also turns out to be MCAS related, do we need to explore the possibility that the MCAS operation in flight, combined with the possibility of Airspeed Unreliable, Stall Warning, Possible Windshear alerts, is much more violent and hard to control than we initially thought?
Two sets of pilots can’t deal with it- is my aircraft actually flyable under these conditions 1000ft above the ground?
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Put another way, if you’ve got a problem why would you choose to stay so low? As someone else said, set power, pick an attitude, get away from the ground and take things from there.
The first question must be - why didn’t/couldn’t the crew do that? Sort of sums-up 600+ Forum posts.
The first question must be - why didn’t/couldn’t the crew do that? Sort of sums-up 600+ Forum posts.
That may be so. Looking at the GS vs time profile shows a gradual, steady acceleration with no spikes. It doesn't look like UAS, particularly given that it's GNSS-derived and not dependent on air data,
How does the old saying go Chris?
Better to remain mute and let people think you are...... Than to open your mouth and remove all doubt!
I honestly can’t see a spin that will extricate certain authorities from this.
Better to remain mute and let people think you are...... Than to open your mouth and remove all doubt!
I honestly can’t see a spin that will extricate certain authorities from this.
Boeing is allegedly to 'deploy a software upgrade' which will 'make an already safe airplane safer'.
In April.
So that's OK then....
Surely the 737 Max8 should be grounded immediately until the cause of the accidents has been established and appropriate modifications incorporated? Boeing has said that the software enhancements include "limiting stabiliser trim commands in response to erroneous readings, pilot displays, operation manuals and crew training". Which sounds rather more than a software upgrade to me....
In April.
So that's OK then....
Surely the 737 Max8 should be grounded immediately until the cause of the accidents has been established and appropriate modifications incorporated? Boeing has said that the software enhancements include "limiting stabiliser trim commands in response to erroneous readings, pilot displays, operation manuals and crew training". Which sounds rather more than a software upgrade to me....
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Krusty 34, agreed. As we’ve found in the UK (Shoreham Hunter crash), sometimes the regulator is a little too close to the action. One trusts that the NTSB keep their excellent reputation.
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I don’t drive the MAX but I think I understand what MCAS does and doesn’t do (maybe). Is it possible that two things could be true and that whilst Boeing have stuffed up on a few different levels as I see it could it also be the case that if training were appropriate neither of these incidents would’ve been fatal?