Ethiopian airliner down in Africa

[CONSO]

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".

I **suspect** ther confusion comes from a much earlier post- probably re lion/maintenance comments that as I ***vaguely *** recall - there is an automatic change/switch of right side to left side computer systems/ TO displays every flight cycle or similar.

[etrang]

Originally Posted by Cows getting bigger

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

First 737 max was delivered in May 2017 so none have been in operation for 2 years. Most have been in operation for less than 1 year. 5 sectors per day is also a very high estimate.

[Old King Coal]

Originally Posted by MD80767 Driver

Captain was Pilot Flying. Addis is a "Capt only" Airport

Not necessarily. In FlyDubai I seem to recall that it was, but in other airlines that I've been in it was not. It depends upon the airline and how they choose to categorise it.

[Chris2303]

Originally Posted by PlatinumFlyer

I profoundly hope and pray this doesn't come back to bite them

[c53204]

Originally Posted by Dee Vee

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?

Sick of hearing the “safety come first” quote. How many accidents have been caused by trying to save money? Do they think people are stupid?

[FCeng84]

Originally Posted by PJ2

Is this correct? Can someone cite the source?

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.

[PJ2]

Thanks very kindly, FCeng84.

The switching from left to right to left etc., would likely be handled by the air-ground condition, I suspect?

[Dark Knight]

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?

[greenfields]

Originally Posted by c53204

Sick of hearing the “safety come first” quote. How many accidents have been caused by trying to save money? Do they think people are stupid?

Well aren't they? They'll go with the dodgiest of airlines to save $50! So the answer is, yes, people are stupid so maybe they are thinking exactly that.

Originally Posted by RatherBeFlying

We are all keenly interested in what the FDR and CVR will show from this second accident.

Either they will show:

1. a similar scenario as Lion or
2. something different.

Barring something out of control by the crew and manufacturer, neither outcome will reflect well on the MAX.

Really? Do we not understand that had the crew in the Lionair accident performed the Runaway Stabiliser NNC then the jet will have in all likelihood have landed safely, as it did when the previous crew followed procedure? The Boeing bulletin is emphasising a procedure that already exists and all 737 crew should be aware of.

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.

[jolihokistix]

(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.

[FlightlessParrot]

Originally Posted by Vessbot

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.

FIL's house in Australia, where down = on. Light switches baffling, because house first built for Finnish sea-captain: Finland, up=on. But not ALWAYS baffling. Anyway, as already pointed out, this is an arbitrary convention: the point is to implement a convention consistently.

[gravityf1ghter]

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?

[Cows getting bigger]

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.

[DaveReidUK]

Originally Posted by fox niner

So? That is outrageously fast 5 minutes into the flight. Even at a “high” airport. You need some serious trimming (either by yourself or by the MCAS) to achieive that.

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,

[KRUSTY 34]

Originally Posted by PlatinumFlyer

Perhaps they should have done so after the first prang. Oh that’s right, they’re the ones who certified the aircraft (and it’s MCAS) in the first place.

The FAA shouldn’t be anywhere near the investigation.

[KRUSTY 34]

Originally Posted by Chris2303

I profoundly hope and pray this doesn't come back to bite them

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.

[BEagle]

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....

[Cows getting bigger]

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.

[Berealgetreal]

One poster summed it up so well.

”imagine you’re the crew walking down the aerobridge to fly one of these things”.

[Jeps]

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?