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).

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

MrBretz wrote:

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

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.

rufusmi wrote:

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

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.

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).

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.

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.

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

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.

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?

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?

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

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.

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.

flyinTLow wrote:

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

trijetsonly wrote:

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

ikramerica wrote:

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

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.

zeke wrote:

No MCAS has nothing to do with elevator feel.

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.

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.

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?

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.

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.

Stitch wrote:

Would QF71 and QF72 be relevant?

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.


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.