Ethiopian airliner down in Africa

[yanrair]

Originally Posted by WHBM

I think there were a number of us surprised that such were a chargeable extra ticket item. It would be interesting to ask if the FAA knew it was such, as (surely the prototype but) also the initial production aircraft used in the certification tests all seem to have been for operators who had selected the AOA comparison option.

Thanks a lot for that feedback on this conference. This refers to a senator saying that AoA indicators should fitted as standard. Fitting AoA indicators is certainly not something that most airlines want even if money were no object. That is why wealthy airlines apart from one perhaps, don't fit them. They can be very confusing, require a lot of training and understanding - far more than the data we already have at our disposal - which many on this forum have said is confusing enough already. An AOA disagree warning would be a good idea and would result in pilots knowing not to trust AoA any more and probably get on the ground asap. and avoid any flight situation that might require their use.
Anyway my concern here is we have people from Donald Trump and now a senator who flies a light aircraft telling the industry how it should be done. An industry that has driven airline deaths to almost zero over the last forty years. Not every year, and 2017 did see one death world wide but to no other industry gets close to those sort of safety improvement statistics.
And of course if the AoA indicators are being fed erroneous information by the AoA sensors then ..................
Y

[PEI_3721]

yanrair, #2644, re ‘it suggest by saying "not easily" that it is in fact possible but not easily”
See thread Boeing advice on "aerodynamically relieving airloads" using manual stabilizer trim which discusses this issue relating to 737 Classics and NG.
I suspect that the AMM ‘not easily’ relates to this discussion. However, for the Max - as yet unknown, there is the possibility that ‘not easily’ could become ‘not at all’ at some point during a MCAS failure situation.

[yanrair]

Originally Posted by bsieker

I am saying no such thing, and it is also irrelevant. I have said all I have to say on this, and I am sorry if you are still missing the point.

The offending sentence in my original post was perhaps a mistake. Since it added no content, I have removed it.


Bernd

P. S. be careful to retain the closing quote bracket, or the forum software will mess up the formatting.

Ok Bseiker, I will be careful and thanks. I thought that you imagined from my comments that I was not a pilot. And I think it is relevant whether a contributor is an airline pilot of just someone asking questions.
I have flown the 737 aircraft many times in manual reversion (no power at all - nothing but a 24 v battery) and in manual trim mode - STAB SWITCHES OFF. In the older days when we did not have a good simulator, we had to do runaway stabilisers on the real plane with a training captain hitting the AND (airplane nose down) button and holding it there until you reacted - and that sometimes was a long time - maybe 10 -15 seconds. I am not sure that too many of our readers have actually done any of this stuff for real - but that doesn't make their commentary any less valuable. I find all of this commentary valuable even though I don't agree with a all of it - I certainly know more about algorithms than I did two weeks ago. It is just that I think the human brain is better at these things than most automation - hence autopilots not being able to land in seriously bad windy weather. Or make decisions when the data coming in doesn't compute - AF 447 sort of scenario and we know what happened there.

[PEI_3721]

A0283, # 2645,
Thank you for a balanced view of AoA, definitely not ‘a safety item’ - you can fly without the display.

Perhaps the Senators (yanrair #2647) should be invited to view:-
#2577 Ethiopian airliner down in Africa

[Realbabilu]

Even MAX Boeing test pilot didnt aware that MCAS is using one sensor data.


https://www.bakersfield.com/ap/news/...7e6384825.html

[gums]

Opinion on the AoA indicator/instrument
_________________________________________
Salute!
Many opinions about the AoA indicator or instrument or....or.....
I must admit that I flew three jets with AoA indications, two presented AoA all the time and one only with gear down.
I liked an AoA indication that presented the optimum AoA for an approach regardless of my weight, and allowed for configuration such as flaps and gear Being a single seater, it kept me from flipping thru a lotta pages and such, and also being more accurate than the old rules of thumb like 175 KIAS with 3,000 pounds and 5 knots for every 1,000 above that ( yep, that was a rocket I flew as a raw nugget).
I never used AoA for optimum cruise or holding pattern to save gas. Although two of my planes used AoA for stall warning and protection, the only indication I had was a pusher or a no kidding FBW limiter on the elevator no matter if I pulled with 200 pounds!
So I tend to agree with many that adding another instrument that can be used for most of the flight is of dubious value. EXCEPT it is worth its weight in gold for approaches and when flying right at the edge of the envelope. So my feeling is to have some. representation presented when those two conditions exist. It's a no brainer. Shows you why you are close to a stall and confirms your approach AoA/speed. I will guarantee that the Asiana 777 that got slow would have seen the AoA bracket going way high in the HUD ( oops? that thing have HUD?). Ditto for AF447.

Finally, many recent posters do not understand how trim works with regard to AoA and pitch attitude and Gee. I suggest they visit the Tech Log.

Gums sends..

[Longtimer]

Boeing has launched fixes for its 737 Max plane

• 1 hour agohttps://www.bbc.com/news/business-47722258

Boeing said in future airlines would no longer be charged extra for that safety system to be installed.Upgrade

The planemaker has also issued an upgrade to the software that has been linked to the crashes.

The Manoeuvring Characteristics Augmentation System (MCAS), designed to keep the plane from stalling, reacts to sensors which detect whether the jet is climbing at too steep an angle.

But an investigation of the Lion Air flight last year suggested the system malfunctioned, and forced the plane's nose down more than 20 times before it crashed into the sea killing all 189 passengers and crew.

The US Federal Aviation Administration says there are similarities between that crash and the Ethiopian accident on 10 March.

Boeing has redesigned the software so that it will disable MCAS if it receives conflicting data from its sensors.Timetable

Boeing said a final version of the software would be submitted to the Federal Aviation Authority (FAA) by the end of the week.

But it added that airlines would have to install the new software, give feedback on its performance, and train pilots before the changes could be certified and the planes passed safe to fly again.

In a briefing to reporters Boeing said that the upgrade to MCAS was not an admission that the system had caused the crashes.

A joint investigation by the U.S. National Transportation Safety Board, France's aviation investigative authority BEA and Ethiopia's Transport Ministry is expected to release a preliminary report into the Ethiopian crash this week.Image copyright Getty Images A Boeing official said: "Following the first incident in Indonesia we followed the results of the independent authorities looking at the data, and, as we are always looking to ways to improve, where we find ways to improve, we make those changes to make those improvements."

FAA is also coming under scrutiny on Wednesday as the Senate Commerce sub-committee on Aviation and Space is due to question its acting head Daniel Elwell as to why the FAA was one of the last of the world's regulatory bodies to ground the plane after the two crashes.

[PJ2]

Originally Posted by Realbabilu

Even MAX Boeing test pilot didnt aware that MCAS is using one sensor data.


https://www.bakersfield.com/ap/news/...7e6384825.html

I understand from having read earlier in the thread that both AoA sensors are used but only one at a time, on alternating flight legs, between the left & right FCCs which are fed by the left & right AoA sensors respectively. It's still a single-point-of-failure issue and as has been stated numerous times throughout this thread, that design requires an answer as to why.

For airline pilots, particularly non-military-fighter types, AoA is a secondary piece of information. If AoA is to be implemented, then mental habits have to change to accomodate a new way of viewing the wing. One cannot make both airspeed and AoA equal in the pilot's mind due to the obvious potential for confusion. Airline pilots fly by speed not AoA, and introducing data on the PFD in an abnormal situation could be confusing in terms of a quick intellectual apprehension, (mental modelling), necessary for timely and correct decision-making. We are accustomed to "obeying" airspeed, not AoA and when the priority suddenly becomes "AoA over speed or pitch", even though perfectly correct, may in a rapidly unfolding situation which is becoming more confusing by the second, render AoA of dubious value.

This is not to dismiss AoA itself as valuable; out of interest, I used to watch it using the ACMS section of the rear MCDU on the A330/A340 when in cruise. But the modelling of behaviours necessary to make it become "primary" in pilot awareness when we've used airspeed as primary forever, is a signifcant change which may not be necessary, for as I have mentioned before, recognizing and using AoA still doesn't have any "saves" to its credit in airline work. It may have such a potential, but planning for or requiring its use is by no means straightforward, as just displaying AoA on the PFD or even installing a comparator does not resolve the question of which parameter to prioritize when AoA's don't match by a set value and set off yet another attention-getting device to which the pilots must intutively react, possibly swiftly.

[Ian W]

Originally Posted by yanrair

Thanks a lot for that feedback on this conference. This refers to a senator saying that AoA indicators should fitted as standard. Fitting AoA indicators is certainly not something that most airlines want even if money were no object. That is why wealthy airlines apart from one perhaps, don't fit them. They can be very confusing, require a lot of training and understanding - far more than the data we already have at our disposal - which many on this forum have said is confusing enough already. An AOA disagree warning would be a good idea and would result in pilots knowing not to trust AoA any more and probably get on the ground asap. and avoid any flight situation that might require their use.
Anyway my concern here is we have people from Donald Trump and now a senator who flies a light aircraft telling the industry how it should be done. An industry that has driven airline deaths to almost zero over the last forty years. Not every year, and 2017 did see one death world wide but to no other industry gets close to those sort of safety improvement statistics.
And of course if the AoA indicators are being fed erroneous information by the AoA sensors then ..................
Y

An AoA disagree was already known to the aircraft systems that is why there was the cascade of other warnings on UAS etc. As was stated upthread slightly more sophisticated software would identify the AoA vane reports that were not behaving within normal parameters. Then the one assumed good AoA could be used with just an alert for the crew that they were now on one AoA. While the new Boeing fix will stop the MCAS issue surfacing, there could be a slightly more sophisticated approach to reduce the instant jump in workload in the cockpit and just provide caution the systems are now using only one AoA ensure pitch and power are correct for each phase of flight (or some such), As was said earlier the 'automation surprise' and cacophony of warnings and systems dropping out only obfuscates what is happening. It is definitely not useful and is likely to create cognitive overload leading to attentional tunneling (tunnel vision) concentrating on something that is actually less important (you have 20 seconds left to hit those switches!!!!). HF people should sit in a cockpit for each type of alert and see how many PANIC PANIC!! warnings are issued that may not actually be totally necessary. All that happens is the majority of these alarms and alerts are not even noticed. So with each failure in a particular flight phase what is the most important alert? Get the pilots' attention on that and do cognitive walkthroughs to find out how the system can assist the pilots. In some flight phases a minor fault could become major and vice versa. Yes they do this with EICAS/ECAM messages etc., but even they scroll off. It just seems a little more thought could be given to prioritization and alerting types you want the right reaction not panic or tunneling.

[Chronus]

AoA Indicators.

There is a good research paper published in 2014 on this subject. I may be accessed at :

https://www.researchgate.net/publica..._Effectiveness

[Bergerie1]

PJ2,

Thank you for a dose of common sense. I have never flown with AoA displays, apart from CofA airtests on VC10s, and I think, for the reasons you state, they would have little value in normal commercial operations. To me, the issue is the single point of failure. To have AoA information from only one sensor for such an important software control system is bizarre, to say the least. I can appreciate that the MCAS is an 'add-on' and thus inherited the existing system architecture of the 737, but I note that a similar system in the military version of the 767 uses inputs from two AoA sensors. Surely three AoA sensor inputs should be used, with a simple voting system to decide which to discard, would be better.

[gums]

Salute!

The problem, Berg, is that the MCAS acts upon AoA because of the aero requirements of the certification. Airspeed , actually Mach, only influences degree of trim. So you can have MCAS trimming you as long as flaps are up, and the intent was for it to help at other than approach speeds or right after takeoff.

PJ. and I and others here went thru this with AF447 a century ago. With all the crapola about MCAS, last thing I want is something new that could confuse the crew, take up space on a display or..... I still like AoA indication for approach/landing. I feel the pilots here know how AoA affects lottsa things and the basic lift equation and induced drag and so forth. But for others, go over to Tech Log and we can talk.

We need one of the 40 second sim pilots to contribute here. Know any? My guess is they demonstrated a scenario that had no pilot trim inputs Nd let the system rip! So add the times and it is 40 seconds. If you do not reduce power, you wind up in a very bad corner of the envelope.

Gums sends...

[Fortissimo]

It seems that the majority of people who see no value in displaying AOA are those who have never used it. It works very well, as I found out when I needed to land at night following a complete loss of IAS, and it works on big aircraft as well as fighters.

An absolute AOA indication (in degrees) is not necessary, far better to have an indexed system, the main point being that it gives you a direct indication of how well your wing is performing - that is extremely useful information when you are near or nearer to the margins, for example on take-off, approach or landing. And if you are on the point of stalling, it is the only thing that will tell you reliably how close to the edge you are. With the right tab data, you can also get a pretty good indication of your AUW by comparing IAS and AOA values, which means you can find out easily if your pax are lardballs who have decided to carry on 15kg apiece - that might mean you being able to add 5kts to Vref in the knowledge that you are maintaining your stall margin on the approach. Would that not be useful information?

I would have AOA displayed any time the gear is down, if the speed is below 200kts (for most large aircraft), or if the stall warner is active. For the latter case, I would bin all other speed cues and display attitude, AOA and altitude until a recovery is obvious. Yes, there will be training required to ensure that IAS-only pilots understand what they are being shown, but once learned, never forgotten.

[A0283]

FYI the Senate hearing just ended after about 2hrs30minutes.

Senator Cruz chairing ... with member Senator Sinema...
Witnesses Messrs Elwell (FAA) has pilot experience on multiple types but not 737, he has flown aircraft with and without AoA indicators,
Sumwalt (NSTB) has commercial pilot experience on the (Flintstone versions of) the 737,
Scovel (DoT IG),
Senators - at least one had pilot experience, another some aviation software development experience.

Some notes after listening through it. Beware - these are my notes and not an official transcript - and is not chronological or complete. I try to give an impression and not an opinion here.

What was interesting is that the senators quoted multiple newspaper (NYT, Reuters, Dallas Morning News, Washington Post, Seattle Times,....) stories to support their questions. A number of the newspapers reports were used by pprune members as input and discussed on this forum.

The issue of AoA - indication, warning light, etc got a lot of attention.

Mr Elwell regularly repeated that the FAA "is the global golden standard of aviation safety". Also regularly repeated that the FAA "is fact based and data driven". Mr Elwell did not answer any YES/NO question. Some of the Senators question were quitely asked, others quite agressive. Mr Elwell repeatedly briefed the president and the DoT secretary on the MAX developments, he briefed the president on his intent of grounding, the president then went to a press conference and talked about grounding, Mr Elwell refused to talk about his conversations with the president.
He repeatedly referred to using the Flight Standardisation Board, how international that was, and how the FSB did not come up with any issues.
Appears Mr Elwell's opinion is that the runaway procedure was enough to cover what happened and that every pilot (in the US) is trained and trained on that, and that it is a memory items, so no need to take up a manual in the cockpit. Which suggests that every pilot would have recognized it as such.
Mr Elwell clearly stated that he sees MCAS as a subsystem of the existing STS system. Suggesting that it is not directly visible to the pilot and therefore not directly trained. And also mentiond a number of times that MCAS only operated in a very thin part of the flight envelope. So MCAS was 'already in the NG under STS'.
He stated that delegation has been around since the 1920's and that 'ODA has been around for 60 years'. His estimate was IIRC that skipping ODA would require 10,000 staff and 1.8 billion dollars. And that the EU 'does more ODA'. On ODA he stated that the shift from enforcement (the tool) to compliance (the end game) was a good one.
He stated that after 57,000 flights in the US there have been no reported MCAS issues. And that SWAPA, APA and ALPA in the US leaders all told him they thought the 737 MAX was safe for US pilots to fly. And that he used that information to decide not to ground the MAX. Also after reading all ASRS 24 reports which in his view were not about MCAS. And review of FDR data of all flights.
In his view AoA indicates an energy state, and opined that pilots have other means to determine that.
He called the Boeing 737 MAX a FBW aircraft a number of times during the hearing.

Mr Sumwalt stated that the cooperation with the Ethiopian authorities till now was good and open. He expected a preliminary Ethiopian report (in the 30 days timeframe I guess) - but indicated the Ethiopians are in the lead.

Mr Scovel discussed a number of earlier IG reports that had some serious issues on the FAA and oversight including ODA (IG report of 2015). Normally an IG investigation takes 10 months, Mr Scovel suggested this one might take a bit longer. The IG are working on a report on the Southwest issues with 737 engines, report expected about August 2019, while the NTSB expects its Final Report in November 2019.

A group of at least 16 senators are drafting a Bill that state that safety critical items may not be sold as optional. Mr Elwell in his way states that this is already so. So this is an interesting point, is this a misunderstanding or a difference of opinion.
A number of senators talk about 'shaken consumer confidence'. Some go much further and suggest the FAA has lost its 'gold standard position'...
A number of 'regulatory capture' and 'whistle blower' questions were asked but not really answered.

[gums]

Salute!

Thank you Fortissimo.

To be honest, we fighter guys never used AoA to fly the 'quickest, tightest turn", or to hang at best AoA as MIGCAP, or to cruise home or let down at optimum AoA.
We used it mostly for approach and landing. And as you said, the absolute AoA was not necessary. What the U.S. Navy and later USAF presented on the modern HUD and "indexer" chevrons on each side of the old gunsites was where you had to go to reach and fly optimum approach AoA. I liked it.

So your idea of having AoA represented in some fashion once gear is down, maybe when flaps are down and gear coming up as for a go around has merit, IM(not so) HO.

Gums sends...

[yanrair]

Originally Posted by RTM Boy

Your first sentence demonstrates the modern phenomenon of fanboyism. But really the problem revolves around competing needs. Fundamentally A/C are tools with which to do a job, they are not, must not, be considered in terms of wafer-thin shallowness as say Nike vs Adidas.

• Passengers want cheap(est) fares. Cheaper fares = more passengers = higher load factor = airline profitability (for a given mean fare).
• So, airlines want lowest cost; low(est) leasing rates, low(est) fuel consumption, low(est) maintenance costs, low(est) training costs for new A/C types, lowest wage rates, maximum airframe and crew utilisation, lowest airport charges, etc, etc.
• Aircraft manufacturers want high volume sales for profitability to amortise fixed and development costs, in part to please investors and in part to create sufficient cash flow to allow development of the next model and so will make what they think the market will buy most of...to the minimum standard permitted in service (ie lowest cost). They will offer 'optional extras' at extra cost to the airlines/leasing agents (ie another profit centre).
• Governments and their aviation regulators want maximum safety (in theory). It's not helpful for your voters to suffer the consequences of your mistakes or to see others do so.

Just this simple construct (yes, I know it's more complicated than that), illustrates the tensions in decision-making and taking. Remember, there is no such thing as 'safe' or 'unsafe'. It's all a matter of degree based on thorough, objective, tested risk assessment. Or it should be. But then everyone has an agenda. Everyone.

Thats all true of any business but good airline management is what it’s about- managing those factors. Qantas has never lost a passenger. Ryanair (from annual report)!has had no fatalities in over thirty years with currently 600 plus737s. Same is true of so many operators. Safety is no accident. It’s as you say risk Assessment and ensuring the highest possible standards.
Y

[GlobalNav]

I know there have been several posts regarding the display of AoA, but with no disrespect for the potential usefulness of the parameter, I seriously doubt its safety benefit for the 737 MCAS scenarios.

It would be good to understand the current flight deck context. Display of AoA, itself, is not a required element of flight information, per the certification regulations and never has been. Further, I doubt that even those airlines which opted to have AoA (i.e., "normalized" AoA) displayed have adopted any flight deck procedures for its use, at least nothing stronger than "you may cross check it". So, what would motivate pilots to pay significant attention to it? Hence, except perhaps for a few former Navy and Marine pilots, I doubt the AoA display even enters the most pilots' instrument scan.

I won't argue that things are the way they should be, but there would be a lot of procedural inertia to overcome to achieve safety benefits from the display of AoA. If this change is attempted, I would suggest a far more prominent display of AoA than is found in current transport aircraft flight decks.

[AerocatS2A]

Originally Posted by smala01

The parallels to XL air crash in the A320 in 2008 are worth a read if you are not familiar... Stuck AoA sensors, no best of three inputs (let alone a single sensor), and un-commanded full forward trim in response to erroneous data inputs.

https://en.wikipedia.org/wiki/XL_Air...ny_Flight_888T

That is a completely false representation of the XL crash. The crew stalled the aircraft while testing the stall protection system. There was a "best of three" inputs, but the two inputs that agreed were wrong. There was no uncommanded full forward trim, in fact the auto-trim wasn't operating at all. You might like to read your own link for further education.

[hans brinker]

Originally Posted by Ian W

An AoA disagree was already known to the aircraft systems that is why there was the cascade of other warnings on UAS etc. As was stated upthread slightly more sophisticated software would identify the AoA vane reports that were not behaving within normal parameters. Then the one assumed good AoA could be used with just an alert for the crew that they were now on one AoA. While the new Boeing fix will stop the MCAS issue surfacing, there could be a slightly more sophisticated approach to reduce the instant jump in workload in the cockpit and just provide caution the systems are now using only one AoA ensure pitch and power are correct for each phase of .... ot panic or tunneling.

No, there was no comparison done between the left and right AOA. The left side incorrectly indicated a very high AOA, the right side indicated correct. The warnings generated (stall/UAS) were all from the left side, and the MCAS was using the left side too.

[HarryMann]

Originally Posted by Takwis

I see a trend going back several days in this thread: people who have not flown with an AOA indicator feel that they are unnecessary or distracting, while those who have flown with them find them a valuable addition to the flight instruments.

At the time I went through Air Force pilot training, everyone flew the T-38, as the "advanced trainer". Supersonic, not quite as fast on final as Gums' bird, but close. Very vague "stall warning"; really, it didn't stall so much as just increase descent rate. You could (and I have) pull the stick slowly back into your lap, full aft, and the plane would maintain a nose up attitude, but descend at greater than 12,000 fpm. That was fine at 30,000 feet, in a MOA, but not optimal on approach. So an AOA indicator was fitted, not on the instrument panel, but on top of the dash, right in your line of sight when looking at the runway. The data was simplified...on airspeed, a green donut. Too fast, a yellow chevron indicating you needed to slow down, too slow, a red chevron indicating you had better increase your airspeed, and mind your sink rate. The instrument was absolutely essential to flying the T-38 well, and everyone in the Air Force for decades had done it. When I got out of pilot training, my next jet was a KC-135 (grand-dad to the 737), and it had two AOA gauges on the dash. Not essential, but a valuable crosscheck, not only on final, but also at long range cruise. Never distracting.

I'm not decrying AoA displays nor for or against just listening to PJ2 Gums et al but....

the T-38 being low aspect ratio has a much greater alpha range up to stall than an airliner so those comparisons may not be that relevant ?