Ethiopian airliner down in Africa

[Ngineer]

Three AOA sensors inputting to MCAS two of which must agree.

Limitation to the forward trim provided by MCAS?

They would do it for me. How difficult/expensive to fit/retrofit.

Prob just a software upgrade. FCC A & B should have a crosstalk bus between the 2. Boeing boffins are probably working on a solution now in order to ensure a single sensor failure does not impact safe aircraft operating envelopes. Both sensors will prob be voted/compared if they weren't previously, or the MCAS deactivated.

Single sensor inputs compared over crosstalk buses between aircraft system computers (redundancies) for the purpose of voting/comparison have often been used in the past. Not sure why single AOA inputs to the FCC were not voted in the first place (if this is the case).

[601]

Three AOA sensors inputting to MCAS two of which must agree.

Unless the system is programmed to use the information from the faulty sensor by commanding the aircraft to resolve an incorrectly perceived situation.

[KB]

AoA Sensor

Am I right? Is the MCAS-System fed by the signal of only one AoA-Sensor?

[A0283]

I was wondering why there have been no official investigation releases quoted here. So took a peak at the Ethiopian CAA website.

+++

Accident Investigation - Information - civilaviation

Accident Investigation

The Ethiopian Civil Aviation Accident Prevention and Investigation Bureau has been established with the following objectives:

· Conducting a thorough investigation

· Identify all root causes of the Accident

· Formulate safety recommendations

· Preventing a recurrence

· Avoiding apportion blame

and the department's role is to:

· Investigate aircraft Accident and Incidents That Occurred in Ethiopian airspace related that Occurred in Ethiopian airspace related To Civil Aircraft operations and publish reports on the final results in a accordance with Ethiopian Legislation and International Civil Aviation Organization (ICAO) Annex-13

· Prevent aircraft Accidents and Incidents and improve Aviation Safety by determining the cause Safety Recommendations intended to prevent recurrence.

· Assure all facts and circumstances leading to an accident or incident are recorded (data base) and evaluated and that action is taken to prevent similar occurrence in the future.

· Follow up implementation of Aviation Safety Recommendations.

+++
and when you look at:

News - civilaviation no news on this accident

Press Release - civilaviation is empty

+++
I am missing something? You would expect them to post on their own website who is leading the investigation and what parties are involved. And for example what the moves are on the flight recorders.

[RetiredBA/BY]

Originally Posted by KB

Am I right? Is the MCAS-System fed by the signal of only one AoA-Sensor?

One would hope not. BUT even the Trident of the 60s had three of everything critical !

[GotTheTshirt]

Re the FAA and grounding I wonder if the FAA would be reluctant to ground an Airbus with the same situation !!

[groundbum]

usually a debris trail stretching back miles, or absence thereof, is a huge clue to air-crash investigators. Any information yet on whether debris has been found miles from the crash site yet?

G

[Skyborne Flyer]

I wouldn't expect that website to update any time soon, seeing as their latest new post in more than a year ago. Any initial reporting of new will probably come through press releases by the participating foreign investigators. Local results will most probably be wrapped up for a good while unfortunately. Might try to get any info by calling or fax though:
T:[phone]
F: 251 11 6650281

[quentinc]

Yes. I guess it isn't only in Europe, that government departments don't have the money to update their websites. You won't find much information on the NTSB site, about this investigation either.

However https://www.ethiopianairlines.com/co.../press-release was providing updates... until they found the Flight Data Recorders. No update since then for some reason.

[El Bunto]

Originally Posted by DaveReidUK

Yes, although AFAIK the altitudes on FR24 always come from Airborne Position messages, which in turn always contain baro alt.

They present both in the web UI, which they call Calibrated Altitude ( barometric ) and GPS Altitude. Edit: apparently this is only visible to Gold and Business subscribers. Sorry plebs

But I haven't dug into their export data to see if they provide both in the downloads. I'll have a look now.

[abdunbar]

Where are the pieces

Information is slow in coming. Eye witness statements of articles and debris falling from the aircraft before final impact should have been confirmed, if true, by recovery of such material. Important question for news media covering the accident; did the aircraft strike anything between takeoff and final resting place? Where was the first item belonging to the aircraft found? If there is any validity to the ads-b data, there was a lot of vertical oscillation close to the ground. It would be possible, admittedly unlikely, that the aircraft struck something prior to the final crash. It's is also possible for the witnesses to be wrong. In any case, there is already more information available to those that know what question to ask. For example, the photo circulating of one of the engines. Looks to have been turning at high speed when it hit the ground. Experts have already no doubt, a rough idea of the speed it was turning when it stopped.

Pressure is building over this accident. Information is not flowing and individuals and groups that are lobbying and withholding are going to suffer consequences.

[FlightCosting]

Originally Posted by LookingForAJob

Not correct - you need to look at the directives that have been issued by each specific State or bloc, relating both to the aircraft type and to use of the States' airspace by those types.

The EASA directive bans the type from taking off landing or Entering EU airspace with or without passengers.

[Sailvi767]

Originally Posted by artee

I think I remember forgetting this before... but as it appears that some of the problems with the 737 Max 8 seem to stem from overextending/overevolving an old-ish plane with short legs, why didn't Boeing develop the 757 instead. More modern plane, longer legs (taller u/c) etc?
Genuine question.

The 757 would not be cost competitive. It was built with performance in mind. To this day there is nothing available with the same runway and range ability. Need to takeoff on a 30C day with 5700 foot runway an fly 2000 miles with a full load of 199 people the 757 is the only game in town. That performance comes at a substantial cost. If the runway is 8000 feet long newer aircraft can do the mission for ⅔ the seat mile cost.

[El Bunto]

They could have derated the 757 as per the 777X, and made up the lost thrust with aero tweaks; there have been a lot of developments since 1980. Also the blueprints for the shorter 757-100 should still be in a locker in Renton.

But that wouldn't have addressed the KPI of the 737 Max: commonality and type rating with the 737NG. That's what drove the whole program and which led to hack upon hack. Southwest would not have bought a 757 Max unless Boeing could price it well under the 737NG, to compensate for the additional operational costs. Southwest wouldn't even consider a clean-sheet design!

Back in the day we used to shake our heads at British manufacturers tying their specs to the whims of BEA and BOAC, but Boeing seem to be falling into that trap with the Max and the 777X ( Emirates-pleaser ).

Anyone writing a history of Boeing in the future will be able to conclude the first section with the 777 and 737NG.

[ReturningVector]

Originally Posted by FlightCosting

The EASA directive bans the type from taking off landing or Entering EU airspace with or without passengers.

No, it allows for up to three non-commercial flight cycles

[A30_737_AEWC]

Originally Posted by ozaub

In long ago days of “excessive government red-tape” new airliners were assessed and certificated by aviation authorities in each country where they flew. For Boeing aircraft we all now rely on certification by the US Federal Aviation Administration and in turn FAA delegates most analysis and testing to Boeing.

Until recently senior company engineers called ''Designated Engineering Representatives'' assessed compliance on behalf of FAA. Delegation went further on the Boeing 787. It was first airliner approved under a new ''Organisation Designation Authorisation'' (ODA) arrangement, specifically intended to reduce FAA involvement.

Somehow hazardous lithium ion batteries slipped undetected through the new procedures. Several batteries caught fire and the 787 was grounded. Independent National Transportation Safety Board investigators found:

• “Boeing’s electrical power system safety assessment did not consider the most severe effects of a cell internal short circuit and include requirements to mitigate related risks, and the review of the assessment by Boeing authorized representatives and Federal Aviation Administration certification engineers did not reveal this deficiency."
• ”Boeing failed to incorporate design requirements in the 787 main and auxiliary power unit battery specification control drawing to mitigate the most severe effects of a cell internal short circuit, and the Federal Aviation Administration failed to uncover this design vulnerability as part of its review and approval of Boeing’s electrical power system certification plan and proposed methods of compliance."
• "Unclear traceability among the individual special conditions, safety assessment assumptions and rationale, requirements, and proposed methods of compliance for the 787 main and auxiliary power unit battery likely contributed to the Federal Aviation Administration’s failure to identify the need for a thermal runaway certification test.”

737 Max is second aircraft to be certificated under ODA. After two fatal accidents FAA and Boeing claim the aircraft is safe but admit that mandatory design changes are needed to a Maneuvering Characteristics Augmentation System (MCAS) which is unique to the MAX.

In a “Continued Airworthiness Notice to the International Community” FAA says its “oversight activities” include:

• Boeing’s completion of the flight control system enhancements, which provide reduced reliance on procedures associated with required pilot memory items. The FAA anticipates mandating these design changes by AD no later than April 2019.
• Design changes include:

1. · MCAS Activation Enhancements
2. · MCAS AOA Signal Enhancements
3. · MCAS Maximum Command Limit

Which confirms Boeing is running the show and almost invites foreign authorities to play safe and ground the Max.

Who’s ever heard of a “CANIC”? Surely a Notice of Proposed Rule Making is required?

Boeing and FAA swept Lionair accident under the carpet but cannot do same with Ethiopian because it’s more reputable and real people (US and UN) were killed; not just Indonesians on an LCC.

I appreciate the manner in which you've outlined the fact that more activity/responsibility has been delegated to the OEMs by the most significant international airworthiness regulator. I also find merit in the way you've explained the design/certification shortfalls around the application of lithium ion batteries in the 787. I remember following those issues in the media and publicly available materiel and being astonished at how a system safety program could have missed some of the crucial issues that resulted in fires on aircraft due to elements of the aircraft's own systems (not cargo).

Like you, I found myself perplexed by what a 'Continued Airworthiness Notice to the International Community' (CANIC) was supposed to be. I'd never heard of them before and there's not a register of them that I was able to find on the FAA website. I think it was rather telling that when I read about the 737 MAX CANIC in the media and tried to find a copy of it for myself, an FAA Twitter 'tweet' provided a link to the document. It hardly looks likes it's a legal airworthiness document (like an AD, NPRM, etc.). It sounds more like a 'child of the social media age' being promulgated by 'tweet' and being crafted by the 'brand managers' of the organisation whose product is found to be wanting in a crisis.

[DaveReidUK]

Originally Posted by FlightCosting

The EASA directive bans the type from taking off landing or Entering EU airspace with or without passengers.

Yes, though there is provision for a positioning (non-revenue) flight to get an aircraft back to base.

There have been a few of those in the last 12 hours since the restriction went live.

[cats_five]

I saw an eye witness on BBC who was sure there was NO fire before the plane crashed. Eye witnesses are not always reliable.

[Cleared Visual]

Originally Posted by 22/04

To restore confidence in the aircraft - what?

Although I am not a pilot, I have some experiencing in testing (non aviation) automated systems and have seen some poorly written code before. I think Silverstrata summed up a simple fix that might be a step in the right direction.

Originally Posted by silverstrata

It did not even bother checking with the other AoA sensor. All you need is one line of code that says: “if AoA1 not equal to AoA2, deactivate system”. I mean, how hard was that? Ok, it would be nice to have three sensors, but even two can resolve that there is an error somewhere, so the system should not start trimming.

And while we are at it, why was there not a line of code that says: “if ASI greater than 210 kts, deactivate system”. I mean, how hard was that? Please don’t say that high speed stalls are a real problem with the Max, because I will not buy that one.

Silver

[Mad As A Mad Thing]

CANIC

I hadn't heard of a CANIC before either. I suspect it's one category short of a full PANIC.