Ethiopian airliner down in Africa

[Speed of Sound]

Originally Posted by bucoops

Maybe just prevent journalists from getting on?

Journalists tend not to involve themselves in discussions but prefer to just lift chunks of it, often out of context, and don't even have to register as this is a public site.

[Sailvi767]

Originally Posted by OLVpilot

Not really. The crew put that aircraft into a stall after they failed to apply basic aeronautical techniques for stall recovery.

Big difference between that and an aircraft pitching uncontrollably nose down at low altitudes.

A aircraft with uncommanded trim does not pitch uncontrollably nose down. As the trim motor adds nose down trim up elevator can compensate until the stabilizer overpowers the elevator. At that point the nose will start down. Normally it’s a smooth progression unless the aircraft is on autopilot. The autopilot disengaging with a out of trim condition will cause a more violent pitching moment. Prior to that however there should be several warning signs. The fix takes about 1 second to activate and the flight should be able to continue with manual trim. Had it happen on a 727. It was a non issue. Trim ran away nose down, trim disconnected and flight continued.

[ph-sbe]

Originally Posted by Snyggapa

Well, in theory you should design to be safe for the worst crews on their worst days. Even if something is designed to be usable by the "average crew", nearly half of your pilots on a given day will be below the level that you designed for.

In technical certifications, we create three standard candidates for the test we're about to write:

- The Clearly Acceptable Candidate: this is a candidate who should pass the exam with minimal to no preparation;
- The Minimally Acceptable Candidate: this is a candidate who should pass the exam with some preparation. Some will pass with high marks, while some will score the cut-score or just above;
- The Not Acceptable Candidate: this is a candidate who lacks the proficiency to pass the exam and should fail;

Any system that you design should be built to the specs of the Minimally Acceptable Candidate: someone who is unfamiliar with the matter (let's say, a pax) does not necessarily need to understand the system. However, those who are trained and licensed to fly should be able to understand the system without much difficulties. If one needs to be an expert on the system itself in order to use it, it is by definition unusable.

Similar to the big internet. Everyone reading this uses the internet, but I doubt more than 1% will even remotely know what a BGP community is. And that's fine, because this system was designed for the "average" user.

When I passed my Private's checkride, I had a reasonable understanding of the 172 I was flying. Engine, electrical systems, flight controls, instruments; the lot. I even understood the workings of the shimmy dampener (it does help if you fly an aircraft with a broken shimmy for a change). Any airman should be able to understand MCAS, or any other flight system for that matter, even on a bad day. If not, then either the system is too complex and risky to introduce, or the airman should not have received their license and rating(s).

[GHOTI]

Originally Posted by sSquares

Average of 350 plane years of operation. (0 to 350 over 2 years) Two hulls lost. Next hull loss will be 6 months from today (on average.)

This equates to a dangerous aircraft on my matchbox. Anyone else get a different mathematical answer?

I am reminded of Concorde, which with one accident went, statistically speaking, from the safest to deadliest airliner then flying.

[42...]

Originally Posted by Sunfish

Now is probably a great time to buy Boeing shares. I have rarely seen such utter tripe talked over two accidents that look, at least at first glance, to be caused by sub standard pilots getting caught by the same tricky but surviveable system failure. Read the 3$%^&ing Boeing AD! Another reason to stop putting undertrained muppets in airline pilot seats.

P.S To ‘Rananim” a pilot of a large passenger jet will NOT be able to distinguish between a faulty sensor and a “real” stall since the aircraft is not certified to stall at all, it is never intended to be stalled, nor does it provide the physical warnings of an incipient stall. That is the reason for all those stall protection systems! That is also the reason for extensive training on systems and their failure modes.

Not certified to stall? Hogwash, we just did full stall recoveries in the sim. Extreme buffet, wingrocking, 6000 plus vvi sinking stalls. This however was not a MAX sim.

[mattymagoo]

Has anyone considered the idea that MCAS was activated appropriately and the crew fought through it even though it was trying to “help” them? ie- they were in a nose high, low airspeed condition. I believe in the Colgan Dash-8 crash, the Captain pulled through the shaker and pusher not believing the aircraft had stalled but (speculation) perhaps believed he was in a tailplalne stall.

[mattymagoo]

Originally Posted by 42...

Not certified to stall? Hogwash, we just did full stall recoveries in the sim. Extreme buffet, wingrocking, 6000 plus vvi sinking stalls. This however was not a MAX sim.

6000’?? I saw 9999 when I did my EET!

[JamesT73J]

Originally Posted by ph-sbe

In technical certifications, we create three standard candidates for the test we're about to write:

- The Clearly Acceptable Candidate: this is a candidate who should pass the exam with minimal to no preparation;
- The Minimally Acceptable Candidate: this is a candidate who should pass the exam with some preparation. Some will pass with high marks, while some will score the cut-score or just above;
- The Not Acceptable Candidate: this is a candidate who lacks the proficiency to pass the exam and should fail;

Any system that you design should be built to the specs of the Minimally Acceptable Candidate: someone who is unfamiliar with the matter (let's say, a pax) does not necessarily need to understand the system. However, those who are trained and licensed to fly should be able to understand the system without much difficulties. If one needs to be an expert on the system itself in order to use it, it is by definition unusable.

Similar to the big internet. Everyone reading this uses the internet, but I doubt more than 1% will even remotely know what a BGP community is. And that's fine, because this system was designed for the "average" user.

When I passed my Private's checkride, I had a reasonable understanding of the 172 I was flying. Engine, electrical systems, flight controls, instruments; the lot. I even understood the workings of the shimmy dampener (it does help if you fly an aircraft with a broken shimmy for a change). Any airman should be able to understand MCAS, or any other flight system for that matter, even on a bad day. If not, then either the system is too complex and risky to introduce, or the airman should not have received their license and rating(s).

Aviation, particularly transport aviation, is a high-performance profession; constant training and knowledge are fundamental for safe operations.

Like nuclear engineering or medicine, procedure is king. However, the operator needs sufficient knowledge to understand "What's it doing? Why is it doing it? Do I need to stop it? How do I stop it? What else does stopping it do?". It's a bit sad to see some sentiment that the crew are just trained to watch the computers (see the old pilot and dog in the cockpit joke) and follow the QRH, otherwise they might be overwhelmed. I really doubt it, in most cases. Aviation got to where it is because of these practices, via some extremely tough lessons.

[Ancient-Mariner]

Both the FDR and CVR have been found.
https://www.bbc.co.uk/news/world-africa-47521744

[Jorge Newberry]

Aerolineas Argentinas pilots concerned and demanding a decision from management. My guess is that if the decsion isn't to ground the Max they'll decline to operate it till matters are clarified

https://www.pagina12.com.ar/180169-p...olineas-argent

[EDLB]

Originally Posted by Sunfish

to be caused by sub standard pilots getting caught by the same tricky but surviveable system failure.

Utter drivel. The plane came down on a clear sky, CAVOK day in daylight conditions. From the momentum obvious with two working donks. Even a substandard pilot should not fall in this conditions out of the sky with a brand new plane.
We most likely know now with 20/20 hindsight, that the AD was not a sufficient reaction to prevent further fatalities.

[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

[SigWit]

Originally Posted by mattymagoo

Has anyone considered the idea that MCAS was activated appropriately and the crew fought through it even though it was trying to “help” them? ie- they were in a nose high, low airspeed condition. I believe in the Colgan Dash-8 crash, the Captain pulled through the shaker and pusher not believing the aircraft had stalled but (speculation) perhaps believed he was in a tailplalne stall.

They were not in a speed low situation. Their speed was steadily increasing.

[glennfish]

alleged video of crash

on twitter. I can't post URL. twitter account JuguarNana

[GotTheTshirt]

Is there some logic in having a couple of switches operating in the opposite sense to the rest ??

[silverstrata]

Originally Posted by Sailvi767

A aircraft with uncommanded trim does not pitch uncontrollably nose down. As the trim motor adds nose down trim up elevator can compensate until the stabilizer overpowers the elevator. At that point the nose will start down. Normally it’s a smooth progression unless the aircraft is on autopilot.

Says someone who has never flown the 737.

The 737 may have hydraulic power assist to the controls, but please do not think of this as the equivalent of power steering on a car. To counteract the MCAS trim forwards you need to pull with some 60 kg of force, using both control columns, to stop the aircraft nosing into the ground. If you are not prepared for that, or you are busy with something else, you are going down....

Originally Posted by GotTheTshirt

Is there some logic in having a couple of switches operating in the opposite sense to the rest ??

It was a deliberate ploy by Boeing, to confuse everyone.
A bit like placing the fire handles (and fire warning lamps) out of your field of vision - to confuse you even more.

(The fire handles were originally on the coaming, in front, but Boeing needed somewhere to put the MCP on the classic series. So rather than designing a new flightdeck, they shoved the fire handles on the center panel, where you cannot see them, nor easily access them. The 737-Max still has the standard B-707 and 727 flight deck.)

Silver

[Vessbot]

Originally Posted by GotTheTshirt

Is there some logic in having a couple of switches operating in the opposite sense to the rest ??

Yes. The scheme is, on any vertical surface (like the instrument panel, or a wall) up = on, same as any switch in the rest of the world. On any horizontal surface (center pedestal, or overhead) forward = on. For the center pedestal, the forward = on scheme elegantly matches what you're used to (toward the top of your eyeball = on). But I've always thought that that's a stupid application on the overhead, which gives the feeling of upside down switches since it reverses the "toward the top/bottom of your eyeball" relationship, and instead it should just be treated like a wall.

And the 737 seems to have very few switches in places that aren't the overhead, so the overhead upside-down scheme prevails. But the stab cut out switches are on a place where the normal (up = on) scheme is in place.

[gums]

@ Indigo A mod too far?
Salute!
For those wondering why MCAS is being discussed. A brief look.
As discussed on another forum and its references, the MCAS was implemented to cope with some aerodynamic "characteristics", as the name suggers:" Maneuvering Charteristics Augmentation System" As others have pointed out, the new engines and their mounting can provide nose up forces at higher than normal AoA. So looks to this old pilot, who has lottsa high AoA experience, the MCAS was supposed to make it harder to command more nose up.

I include a small diagram of pitch coefficient for one plane I flew. At one AoA and higher, the plane "digs in" with neutral controls, and further, it "pitches up" even with forward stick. So it is not surprising Boeing would add something to "help" keep the nose down and not enter that arena where even nose down commands would not be enough. A poster has commented that the 737 stall has plenty of warning, and I doubt it has that one area where nose down stick won't help. Nevertheless, the MCAS looks like it will make it hard to get there. We saw over 100 pounds of back force for JT610 once the trim was way nose down.



You can see the problem.

Gums sends....

[rog747]

Several more airlines pull the 737 Max after the 2nd crash in Ethiopia.

Royal Air Maroc RAM, and now BA RSA franchise Comair.

This afternoon German press Spiegel say TUI HQ is now considering the grounding of its Boeing 737 Max 8 aircraft . "We are in close contact with Boeing and will evaluate soon the situation with the manufacturer," said Tuifly spokesman Aage Dünhaupt.
But TUI UK are not saying much.
The fleet of the world's largest travel group Tui now includes 15 jets of this type, which are stationed in the United Kingdom and the Benelux countries.

[calypso]

you are busy with something else

You cannot be busy with ANYTHING else. Not with unreliable airspeed. AVIATE, NAVIGATE, COMMUNICATE.

I have lost count the number of times that I had to ask the PF to fly the aircraft and I will do any thing required heads down. while at low level. Even in the sim with abnormals people just get sucked into the MCDU while PF. Unreliable airspeed means the PF has to set 80% n1 and fly 10 degrees pitch, that is his only job. If the trim is running against you it should be quite obvious right away as it will be harder and harder to fly 10 degrees pitch. If you are trying to do something else at the same time by the time you look at the pitch again it might be too late.