airboeingbus
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Does the A320 have a MCAS like system?

Wed Apr 03, 2019 8:40 pm

As we know the A320 is a full FBW aircraft and has many protection systems. Does the A320 have a MICAS type system as part of its flight envelope protections. If so under the same circumstances as the recent Ethiopian crash what would have happened on the A320? Also what about aircraft that don’t have manual trim wheels? I know the A320 does have them but later AB models don’t?
 
cedarjet
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Re: Does the A320 have a MCAS like system?

Wed Apr 03, 2019 8:49 pm

The fully mature FBW system covers every flight regime. It is Frankenstein mash-ups like adding something new (MCAS) to an old, mechanical plane (the 737) where you get conflicts. Airbus had a bad run with A300s that were half mechanical half FBW, with two A300-600Rs of China Air Lines crashing in identical situations where the stab trimmed itself all the way nose UP in a go-around, with the pilots fighting it into a vertical climb, stall, and crash on or next to the runway; and a couple of A310s doing the same thing, but (perhaps due to a more favourable thrust-to-weight ratio) didn't hit the ground -- TAROM over Paris, and Interflug over Moscow (both on YouTube and absolutely SPECTACULAR).
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
 
ZBBYLW
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Re: Does the A320 have a MCAS like system?

Wed Apr 03, 2019 8:55 pm

Its a much more intergrated system rather than an add on. We can also disable the protections by the press of two buttons and turn off all the fancy stuff.
Keep the shinny side up!
 
PixelPilot
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Re: Does the A320 have a MCAS like system?

Wed Apr 03, 2019 9:19 pm

cedarjet wrote:
The fully mature FBW system covers every flight regime. It is Frankenstein mash-ups like adding something new (MCAS) to an old, mechanical plane (the 737) where you get conflicts. Airbus had a bad run with A300s that were half mechanical half FBW, with two A300-600Rs of China Air Lines crashing in identical situations where the stab trimmed itself all the way nose UP in a go-around, with the pilots fighting it into a vertical climb, stall, and crash on or next to the runway; and a couple of A310s doing the same thing, but (perhaps due to a more favourable thrust-to-weight ratio) didn't hit the ground -- TAROM over Paris, and Interflug over Moscow (both on YouTube and absolutely SPECTACULAR).


Every??
https://aviationweek.com/commercial-avi ... e-incident
 
marcelh
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Re: Does the A320 have a MCAS like system?

Wed Apr 03, 2019 9:22 pm

PixelPilot wrote:
cedarjet wrote:
The fully mature FBW system covers every flight regime. It is Frankenstein mash-ups like adding something new (MCAS) to an old, mechanical plane (the 737) where you get conflicts. Airbus had a bad run with A300s that were half mechanical half FBW, with two A300-600Rs of China Air Lines crashing in identical situations where the stab trimmed itself all the way nose UP in a go-around, with the pilots fighting it into a vertical climb, stall, and crash on or next to the runway; and a couple of A310s doing the same thing, but (perhaps due to a more favourable thrust-to-weight ratio) didn't hit the ground -- TAROM over Paris, and Interflug over Moscow (both on YouTube and absolutely SPECTACULAR).


Every??
https://aviationweek.com/commercial-avi ... e-incident

What are you trying to prove?
 
flyinTLow
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Re: Does the A320 have a MCAS like system?

Wed Apr 03, 2019 9:38 pm

Going back to the original question and ignoring the childish dispute/bashing:

The MCAS can (and by no means should, as the MCAS' main purpose as far as I understand it is to give a feel to the pilots, while the Airbus flight control laws actually have a protection and avoid the pilot from enterin a certain aerodynamic "zone") be compared to the high angle-of-attack protection in normal lawas well as the low speed stability in alternate law.

But there are MAJOR differences which make the Airbus system more advanced, from an engineering point at least.

1. Airbus' flight control laws rely on correct data input enormously. That is why these systems are fed with at least 3 systems (Airbus A350: 4, don't know about the A380) and constantly compared to assure correct data. If one differs it is locked out by the system, most of the time along with a warning that there could be a problem. If the remaining 2 differ, the system degrades and such protections are then shut down (direct law) or at least minimized to a degree that they can be overruled by the pilots. I am not saying that this is without a possibility for failure as well (e.g. A320 Perpignan crash), but it is far less likely than the case with the MCAS system.

2. While the MCAS system changes the trim, the Airbus' system actually commands elevator deflection. So when cutting off the system, in general you get a more trim-neutral aircraft that is far better recoverable than what I am assuming is the case when cutting out the MCAS.

flyinTLow
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MrBretz
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Re: Does the A320 have a MCAS like system?

Wed Apr 03, 2019 11:11 pm

I am a Boeing fan. I have always have been. I like Airbus too. As a passenger, I rate an airplane based on my comfort which I know has almost nothing to do with B or A but only the airline. Having worked in technology my entire life, I know you can over automate. And it disturbs me pilots seem to mind the automation, whether it is A or B, instead of flying the plane. But I am now having second thoughts. It is time for Boeing to build a narrow body FBW plane. The 737 can undoubtedly be make safer. But, as I understand it better, it is really looking like a kludge at this time of airplane evolution.

On a related thought, are the regional jets FBW or more traditional technology like the 737?
 
DenverTed
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Re: Does the A320 have a MCAS like system?

Wed Apr 03, 2019 11:21 pm

I assume for all these aircraft with new large engines, at higher AOA, the center of lift moves forward with the engines producing more lift ahead of the wing. How close is the center of lift to going forward of the center of gravity? What do the graphs look like for righting moment versus AOA, at the critical configuration, maximum nose up stabilizer and various nose up elevator angles? How much righting moment is left to spare on these new relatively larger fan aircraft, in this region of flight?
 
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WildcatYXU
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Re: Does the A320 have a MCAS like system?

Wed Apr 03, 2019 11:58 pm

MrBretz wrote:
On a related thought, are the regional jets FBW or more traditional technology like the 737?


The older regional jets are traditional. The CRJ 1000 has a FBW rudder. The E-jet, A220, MRJ and the SSJ100 are fully FBW.
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rufusmi
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 12:08 am

WildcatYXU wrote:
MrBretz wrote:
On a related thought, are the regional jets FBW or more traditional technology like the 737?


The older regional jets are traditional. The CRJ 1000 has a FBW rudder. The E-jet, A220, MRJ and the SSJ100 are fully FBW.


I believe the E-jets are only partially FBW, however the E2 is fully FBW.
 
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WildcatYXU
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 12:24 am

rufusmi wrote:
I believe the E-jets are only partially FBW, however the E2 is fully FBW.


Thanks. For some reason I thought the E-jets are fully FBW.
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Maksvell88
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 12:49 am

WildcatYXU wrote:
rufusmi wrote:
I believe the E-jets are only partially FBW, however the E2 is fully FBW.


Thanks. For some reason I thought the E-jets are fully FBW.


Yes E-jets have aileron cables as a back up.
 
rbavfan
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 1:45 am

cedarjet wrote:
The fully mature FBW system covers every flight regime. It is Frankenstein mash-ups like adding something new (MCAS) to an old, mechanical plane (the 737) where you get conflicts. Airbus had a bad run with A300s that were half mechanical half FBW, with two A300-600Rs of China Air Lines crashing in identical situations where the stab trimmed itself all the way nose UP in a go-around, with the pilots fighting it into a vertical climb, stall, and crash on or next to the runway; and a couple of A310s doing the same thing, but (perhaps due to a more favourable thrust-to-weight ratio) didn't hit the ground -- TAROM over Paris, and Interflug over Moscow (both on YouTube and absolutely SPECTACULAR).


OK only TAROM video's are animation. While gives an idea what happened it's not spectacular.
 
ikramerica
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 2:23 am

Airbus has had more than one instances where their FBW system has overtrimmed due yo false AoA readings. In a recent incident (this decade) the pilots had no knowledge of how to turn it off but hecause they were able go keep things level (after initial dive of 4000 feet) they had lots of time for ground based engineers to figure out what to turn off.

The difference was that rather than trim down in spurts, the airbus system trimmed down and then effectively reset that as the new “zero” but it still would havd crashed the plane if it happened in climb out, not FL240.
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zeke
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 3:33 am

ikramerica wrote:
Airbus has had more than one instances where their FBW system has overtrimmed due yo false AoA readings. In a recent incident (this decade) the pilots had no knowledge of how to turn it off but hecause they were able go keep things level (after initial dive of 4000 feet) they had lots of time for ground based engineers to figure out what to turn off.

The difference was that rather than trim down in spurts, the airbus system trimmed down and then effectively reset that as the new “zero” but it still would havd crashed the plane if it happened in climb out, not FL240.


Can you tell which incident this was ?

AF447 happened 10 years ago, since then industry wide changes were made with pilot training (especially recovery procedures) and some Airbus QRH procedures. I have a lot of difficulty believing your claim.

ICAO with Airbus, ATR, Boeing, Bombardier, and Embraer jointly developed ICAO 10011. Airlines have been training pilots to this for some time on this now. https://www.icao.int/Meetings/LOCI/Docu ... aft_en.pdf
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flyinTLow
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 8:08 am

ikramerica wrote:
Airbus has had more than one instances where their FBW system has overtrimmed due yo false AoA readings. In a recent incident (this decade) the pilots had no knowledge of how to turn it off but hecause they were able go keep things level (after initial dive of 4000 feet) they had lots of time for ground based engineers to figure out what to turn off.

The difference was that rather than trim down in spurts, the airbus system trimmed down and then effectively reset that as the new “zero” but it still would havd crashed the plane if it happened in climb out, not FL240.


I am only aware of 1 instance where the Airbus fly by wire system mistrimmed the aircraft (XL Airways 888T, https://en.wikipedia.org/wiki/XL_Airways_Germany_Flight_888T) and in that incident frozen AoA sensors caused 2 of 3 AoA sensors to be stuck on a wrong reading causing the FBW system to trim with this erroneous data.

All other incidents I am aware of always concerned wrong rudder deflection, but please fill me in on this/these incident(s).

Cheers,
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greg85
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 8:32 am

zeke wrote:
ikramerica wrote:
Airbus has had more than one instances where their FBW system has overtrimmed due yo false AoA readings. In a recent incident (this decade) the pilots had no knowledge of how to turn it off but hecause they were able go keep things level (after initial dive of 4000 feet) they had lots of time for ground based engineers to figure out what to turn off.

The difference was that rather than trim down in spurts, the airbus system trimmed down and then effectively reset that as the new “zero” but it still would havd crashed the plane if it happened in climb out, not FL240.


Can you tell which incident this was ?

AF447 happened 10 years ago, since then industry wide changes were made with pilot training (especially recovery procedures) and some Airbus QRH procedures. I have a lot of difficulty believing your claim.

ICAO with Airbus, ATR, Boeing, Bombardier, and Embraer jointly developed ICAO 10011. Airlines have been training pilots to this for some time on this now. https://www.icao.int/Meetings/LOCI/Docu ... aft_en.pdf



It was Lufthansa. It had a big impact on training for airbus operators after the incident. It means that this problem is better understood now.

The Lufthansa example happened because 2 AOA vanes were frozen in the same position. So, it was still a less likely scenario than the 737 MAX which relies on a single AOA for its MCAS system.

You mentioned AF447, but that really isn’t relevant to this conversation. The causes and factors that led to that crash are very different to what we’re talking about here.
 
trijetsonly
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 9:39 am

greg85 wrote:
zeke wrote:
ikramerica wrote:
Airbus has had more than one instances where their FBW system has overtrimmed due yo false AoA readings. In a recent incident (this decade) the pilots had no knowledge of how to turn it off but hecause they were able go keep things level (after initial dive of 4000 feet) they had lots of time for ground based engineers to figure out what to turn off.

The difference was that rather than trim down in spurts, the airbus system trimmed down and then effectively reset that as the new “zero” but it still would havd crashed the plane if it happened in climb out, not FL240.


Can you tell which incident this was ?

AF447 happened 10 years ago, since then industry wide changes were made with pilot training (especially recovery procedures) and some Airbus QRH procedures. I have a lot of difficulty believing your claim.

ICAO with Airbus, ATR, Boeing, Bombardier, and Embraer jointly developed ICAO 10011. Airlines have been training pilots to this for some time on this now. https://www.icao.int/Meetings/LOCI/Docu ... aft_en.pdf



It was Lufthansa. It had a big impact on training for airbus operators after the incident. It means that this problem is better understood now.

The Lufthansa example happened because 2 AOA vanes were frozen in the same position. So, it was still a less likely scenario than the 737 MAX which relies on a single AOA for its MCAS system.

You mentioned AF447, but that really isn’t relevant to this conversation. The causes and factors that led to that crash are very different to what we’re talking about here.


I guess we are talking about this incident?
http://www.avherald.com/h?article=47d74074/0000&opt=0
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PixelPilot
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 1:20 pm

marcelh wrote:
PixelPilot wrote:
cedarjet wrote:
The fully mature FBW system covers every flight regime. It is Frankenstein mash-ups like adding something new (MCAS) to an old, mechanical plane (the 737) where you get conflicts. Airbus had a bad run with A300s that were half mechanical half FBW, with two A300-600Rs of China Air Lines crashing in identical situations where the stab trimmed itself all the way nose UP in a go-around, with the pilots fighting it into a vertical climb, stall, and crash on or next to the runway; and a couple of A310s doing the same thing, but (perhaps due to a more favourable thrust-to-weight ratio) didn't hit the ground -- TAROM over Paris, and Interflug over Moscow (both on YouTube and absolutely SPECTACULAR).


Every??
https://aviationweek.com/commercial-avi ... e-incident

What are you trying to prove?


Facts are facts, no need to prove anything.
By stating "every" he killed the entire argument.
Facts > everything else.
 
trent772
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 1:21 pm

Funny how the tables have turned, not long ago people were calling the airplanes from Touluse the “ScareBus” together with stupid catch phrases like “if it is not Boeing, I’m not going”, now it is quite clear that at least in the narrobody side of the business Airbus offers a far superior flight controls/flight envelope design.
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Weatherwatcher1
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 1:23 pm

airboeingbus wrote:
As we know the A320 is a full FBW aircraft and has many protection systems. Does the A320 have a MICAS type system as part of its flight envelope protections. If so under the same circumstances as the recent Ethiopian crash what would have happened on the A320? Also what about aircraft that don’t have manual trim wheels? I know the A320 does have them but later AB models don’t?


I don’t think anyone can actually answer your question. We can only speculate.

The A320 does have an automatic trim system. It also has an alpha protection where the flight control computers will intervene to prevent a stall. While not a direct cause, the alpha protection system was active in the Air France 296 crash.

The XL888T crash was a case of a problem with AOA sensors during a test flight. The aircraft's computers received conflicting information from the three angle of attack sensors. The aircraft computer system’s programming logic had been designed to reject one sensor value if it deviated significantly from the other two sensor values. In this specific case, this programming logic led to the rejection of the correct value from the one operative angle of attack sensor, and to the acceptance of the two consistent, but wrong, values from the two inoperative angle of attack sensors. This resulted in the system's stall protection functions responding incorrectly to the stall, making the situation worse, instead of better. In addition, the pilots also failed to recover from an aerodynamic stall in a manual mode in which the stabilizer had to be set to an up position to trim the aircraft. But only the stick was applied forward, the aircraft did not trim itself because it was switched to full manual mode. Seconds later the plane crashed into the sea.

On various airplanes, The logic is different, but more or less all jets have a stall prevention system. Some use a stick pusher, some limit elevator position, some command elevator position, some move the stabilizer, some inhibit the stabilizer. Since the designs and logic vary between airplanes, the same circumstances regarding component failures won’t result in the same behavior of the airplane.
 
ikramerica
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 2:07 pm

trijetsonly wrote:
greg85 wrote:
zeke wrote:

Can you tell which incident this was ?

AF447 happened 10 years ago, since then industry wide changes were made with pilot training (especially recovery procedures) and some Airbus QRH procedures. I have a lot of difficulty believing your claim.

ICAO with Airbus, ATR, Boeing, Bombardier, and Embraer jointly developed ICAO 10011. Airlines have been training pilots to this for some time on this now. https://www.icao.int/Meetings/LOCI/Docu ... aft_en.pdf



It was Lufthansa. It had a big impact on training for airbus operators after the incident. It means that this problem is better understood now.

The Lufthansa example happened because 2 AOA vanes were frozen in the same position. So, it was still a less likely scenario than the 737 MAX which relies on a single AOA for its MCAS system.

You mentioned AF447, but that really isn’t relevant to this conversation. The causes and factors that led to that crash are very different to what we’re talking about here.


I guess we are talking about this incident?
http://www.avherald.com/h?article=47d74074/0000&opt=0

I was going from memory. FL310 down to 270.

Some Differences:
Continuous vs intermittent
Cruise vs climb
Time to troubleshoot longer
No trained procedure to stop v memory item (renamed)
Of all the things to worry about... the Wookie has no pants.
 
Elementalism
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 2:12 pm

Weatherwatcher1 wrote:
airboeingbus wrote:
As we know the A320 is a full FBW aircraft and has many protection systems. Does the A320 have a MICAS type system as part of its flight envelope protections. If so under the same circumstances as the recent Ethiopian crash what would have happened on the A320? Also what about aircraft that don’t have manual trim wheels? I know the A320 does have them but later AB models don’t?


I don’t think anyone can actually answer your question. We can only speculate.

The A320 does have an automatic trim system. It also has an alpha protection where the flight control computers will intervene to prevent a stall. While not a direct cause, the alpha protection system was active in the Air France 296 crash.

The XL888T crash was a case of a problem with AOA sensors during a test flight. The aircraft's computers received conflicting information from the three angle of attack sensors. The aircraft computer system’s programming logic had been designed to reject one sensor value if it deviated significantly from the other two sensor values. In this specific case, this programming logic led to the rejection of the correct value from the one operative angle of attack sensor, and to the acceptance of the two consistent, but wrong, values from the two inoperative angle of attack sensors. This resulted in the system's stall protection functions responding incorrectly to the stall, making the situation worse, instead of better. In addition, the pilots also failed to recover from an aerodynamic stall in a manual mode in which the stabilizer had to be set to an up position to trim the aircraft. But only the stick was applied forward, the aircraft did not trim itself because it was switched to full manual mode. Seconds later the plane crashed into the sea.

On various airplanes, The logic is different, but more or less all jets have a stall prevention system. Some use a stick pusher, some limit elevator position, some command elevator position, some move the stabilizer, some inhibit the stabilizer. Since the designs and logic vary between airplanes, the same circumstances regarding component failures won’t result in the same behavior of the airplane.


Your example shows how difficult it is to build these safety systems. From a logic perspective it makes sense to trust two AOA over one. But what are the odds two of them stuck and the third one was correct? Perhaps any inconsistency should cause the system to go neutral trim and at the end of the day the pilots have to fly the plane.

The one that gets me is AF447. Why would they think averaging out the two control inputs without feedback is a good system? Even if you go with that even out system. Provide some form of feedback so the pilot pulling back is wondering why it is so hard while the other pilot is pushing the nose down.
 
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 2:29 pm

trent772 wrote:
now it is quite clear that at least in the narrobody side of the business Airbus offers a far superior flight controls/flight envelope design.

It’s not necessarily that the system is superior, but that pilots are better trained to respond to anomalies since the aircraft has been in service 30 years. But pilots still do wonky things with the flight augmentation system like with QZ 8501. Misunderstanding, and malfunction on the FAC has led to many A32X incidents.
 
RawSushi
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 2:38 pm

flyinTLow wrote:
the MCAS' main purpose as far as I understand it is to give a feel to the pilots


Agreed, and therefore for this reason I would say the A320 has nothing like this. The A320 has flight envelope protection, and MCAS isn't a flight envelope protection feature.
 
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zeke
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 3:26 pm

trijetsonly wrote:
I guess we are talking about this incident?
http://www.avherald.com/h?article=47d74074/0000&opt=0


At the time of that incident there was already a published QRH procedure for ADR disagree which should have been used in that situation. The notes in that procedure mention how events like a bird strike on the nose, volcanic ash etc can interfere with the air data systems.

ikramerica wrote:
Some Differences:
Continuous vs intermittent
Cruise vs climb
Time to troubleshoot longer
No trained procedure to stop v memory item (renamed)


Alfa floor does not change the trim, it is an elevator input, that is the reason why the pilot could control the aircraft by putting in opposite elevator input.

Very different to MCAS, and there was already a QRH procedure in place, the crew on the day did not associate the problem with the ADR.


RawSushi wrote:
flyinTLow wrote:
the MCAS' main purpose as far as I understand it is to give a feel to the pilots


Agreed, and therefore for this reason I would say the A320 has nothing like this. The A320 has flight envelope protection, and MCAS isn't a flight envelope protection feature.


No MCAS has nothing to do with elevator feel.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
RawSushi
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 3:44 pm

zeke wrote:
No MCAS has nothing to do with elevator feel.


http://www.b737.org.uk/mcas.htm
it was introduced to counteract the non-linear lift generated by the LEAP-1B engine nacelles at high AoA and give a steady increase in stick force as the stall is approached as required by regulation.


this lift causes a slight pitch-up effect (ie a reducing stick force) which could lead the pilot to inadvertently pull the yoke further aft than intended bringing the aircraft closer towards the stall.
 
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zeke
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 4:55 pm

Well that is in error, the elevator feel computer works out the loads on the control column. If they just wanted to artificially change the stick force the pilots feel they could have just changed the programming in the elevator feel computer without needing any trim change.

MCAS inserts a 10 second AND trim then reverts to ANU trim. It is physically changing the trim by a constant rate regardless of the stick force.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
flyinTLow
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 7:01 pm

greg85 wrote:
zeke wrote:
ikramerica wrote:
Airbus has had more than one instances where their FBW system has overtrimmed due yo false AoA readings. In a recent incident (this decade) the pilots had no knowledge of how to turn it off but hecause they were able go keep things level (after initial dive of 4000 feet) they had lots of time for ground based engineers to figure out what to turn off.

The difference was that rather than trim down in spurts, the airbus system trimmed down and then effectively reset that as the new “zero” but it still would havd crashed the plane if it happened in climb out, not FL240.


Can you tell which incident this was ?

AF447 happened 10 years ago, since then industry wide changes were made with pilot training (especially recovery procedures) and some Airbus QRH procedures. I have a lot of difficulty believing your claim.

ICAO with Airbus, ATR, Boeing, Bombardier, and Embraer jointly developed ICAO 10011. Airlines have been training pilots to this for some time on this now. https://www.icao.int/Meetings/LOCI/Docu ... aft_en.pdf



It was Lufthansa. It had a big impact on training for airbus operators after the incident. It means that this problem is better understood now.

The Lufthansa example happened because 2 AOA vanes were frozen in the same position. So, it was still a less likely scenario than the 737 MAX which relies on a single AOA for its MCAS system.

You mentioned AF447, but that really isn’t relevant to this conversation. The causes and factors that led to that crash are very different to what we’re talking about here.


I thought you were talking about this incident. As mentioned further down, it was never the system interfering with trim but was adding an elevator down input which could only be counteracted to a certain extent untill 2 ADRs were switched off. There was no mistrimmed aircraft.
- When dreams take flight, follow them -
 
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Stitch
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Re: Does the A320 have a MCAS like system?

Thu Apr 04, 2019 7:49 pm

Would QF71 and QF72 be relevant?
 
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Starlionblue
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Joined: Fri Feb 27, 2004 9:54 pm

Re: Does the A320 have a MCAS like system?

Fri Apr 05, 2019 12:02 am

airboeingbus wrote:
As we know the A320 is a full FBW aircraft and has many protection systems. Does the A320 have a MICAS type system as part of its flight envelope protections. If so under the same circumstances as the recent Ethiopian crash what would have happened on the A320? Also what about aircraft that don’t have manual trim wheels? I know the A320 does have them but later AB models don’t?


Going back to the original question, Airbus FBW does have a high alpha protection system. Once over a certain AoA threshold known as Alpha Prot, pitch control changes from load factor to direct AoA. If AoA increases further all the way to Alpha Max, the system will not allow any further pitch up. (The main conceptual difference compared to MCAS is that Alpha Prot and Alpha Max were not a patch put in place due to a divergence tendency at high AoA.)

On the autothrust side, somewhere between Alpha Prot and Alpha Max, Alpha Floor will set thrust to TOGA.

In the "Ethiopian scenario", one failed AoA vane would not have affected flight control function. Since data from the other AoA probes would be valid, no protection would be triggered. The plane would have climbed out normally, presumably with an ECAM warning such as "F/CTL SENSOR FAULT".

You can see the indications on the speed tape here. Vls is the lowest selectable speed. If speed decays below that, the autopilot disengages (but not on A350). Alpha Floor is not shown on the speed tape.
Image

Manual trim wheels on the A320 and A330/A340. No manual trim wheels on the A350. Just a couple of switches on the center pedestal.
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zeke
Posts: 13694
Joined: Thu Dec 14, 2006 1:42 pm

Re: Does the A320 have a MCAS like system?

Fri Apr 05, 2019 12:08 am

flyinTLow wrote:
I thought you were talking about this incident. As mentioned further down, it was never the system interfering with trim but was adding an elevator down input which could only be counteracted to a certain extent untill 2 ADRs were switched off. There was no mistrimmed aircraft.


No I wasn’t talking about any particular incident, I was asking which incident met this claim made earlier.

The aircraft did not trim (it made an elevator input) and there was the ADR disagree procedure available to the pilots in the QRH however they didn’t apply it.

The difference between changing trim and elevator input may seem like semantics to some. MCAS could actually insert so much AND trim that the elevator was no longer effective. Trim is more powerful and takes longer to move than elevator.

ikramerica wrote:
Airbus has had more than one instances where their FBW system has overtrimmed due yo false AoA readings. In a recent incident (this decade) the pilots had no knowledge of how to turn it off but hecause they were able go keep things level (after initial dive of 4000 feet) they had lots of time for ground based engineers to figure out what to turn off.

The difference was that rather than trim down in spurts, the airbus system trimmed down and then effectively reset that as the new “zero” but it still would havd crashed the plane if it happened in climb out, not FL240.
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zeke
Posts: 13694
Joined: Thu Dec 14, 2006 1:42 pm

Re: Does the A320 have a MCAS like system?

Fri Apr 05, 2019 12:10 am

Stitch wrote:
Would QF71 and QF72 be relevant?


No, does not meet the time frame claimed. That was before AF447.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
flyinTLow
Posts: 491
Joined: Tue Oct 12, 2004 10:40 pm

Re: Does the A320 have a MCAS like system?

Sat Apr 06, 2019 8:08 am

Starlionblue wrote:
airboeingbus wrote:
As we know the A320 is a full FBW aircraft and has many protection systems. Does the A320 have a MICAS type system as part of its flight envelope protections. If so under the same circumstances as the recent Ethiopian crash what would have happened on the A320? Also what about aircraft that don’t have manual trim wheels? I know the A320 does have them but later AB models don’t?


Going back to the original question, Airbus FBW does have a high alpha protection system. Once over a certain AoA threshold known as Alpha Prot, pitch control changes from load factor to direct AoA. If AoA increases further all the way to Alpha Max, the system will not allow any further pitch up. (The main conceptual difference compared to MCAS is that Alpha Prot and Alpha Max were not a patch put in place due to a divergence tendency at high AoA.)

On the autothrust side, somewhere between Alpha Prot and Alpha Max, Alpha Floor will set thrust to TOGA.

In the "Ethiopian scenario", one failed AoA vane would not have affected flight control function. Since data from the other AoA probes would be valid, no protection would be triggered. The plane would have climbed out normally, presumably with an ECAM warning such as "F/CTL SENSOR FAULT".

You can see the indications on the speed tape here. Vls is the lowest selectable speed. If speed decays below that, the autopilot disengages (but not on A350). Alpha Floor is not shown on the speed tape.
Image

Manual trim wheels on the A320 and A330/A340. No manual trim wheels on the A350. Just a couple of switches on the center pedestal.


Glad to see that not all people in the know have fled the site since it became free. Good to have people here that know their stuff should I have a question ;)
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