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HVNwxROC
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Posts: 12
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EasyJet A321 flew out-of-balance after seated for A320

Fri Oct 15, 2021 10:09 pm

https://www.flightglobal.com/safety/eas ... 20.article

I was surprised to read about this, both because it was not caught beforehand and also that it made that much of a difference. But, then I realized that at least the last 9 rows of the plane were likely empty, and perhaps more if the original schemes A320 was not full.

Would the pilot have noticed that it was difficult to rotate during take-off? What other handling/flying issues would or could have occurred?
 
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ikolkyo
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Re: EasyJet A321 flew out-of-balance after seated for A320

Sat Oct 16, 2021 3:25 am

Didn't this happen awhile ago? I can't find the thread about it.
 
bluecrew
Posts: 120
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Re: EasyJet A321 flew out-of-balance after seated for A320

Sat Oct 16, 2021 3:32 am

HVNwxROC wrote:
https://www.flightglobal.com/safety/easyjet-a321neo-flew-out-of-balance-after-passengers-seated-for-a320/145920.article

I was surprised to read about this, both because it was not caught beforehand and also that it made that much of a difference. But, then I realized that at least the last 9 rows of the plane were likely empty, and perhaps more if the original schemes A320 was not full.

Would the pilot have noticed that it was difficult to rotate during take-off? What other handling/flying issues would or could have occurred?

CG's going to be a little north of where it should be, so your stab trim would be significantly off. Uncomfortable, sure, might be a bit sluggish on the rotation, but unless you're operating at the edge of the takeoff envelope it's not great but it's not going to kill you unless you're not paying attention or you have another, major, failure. Probably could cause delayed rotation as the airplane doesn't *smoothly* transition, but with the Airbus FBW it should autotrim to maintain a normal flight envelope pretty quickly. The issues here probably didn't manifest as something overly noticeable to the flight crew, the differences aren't stark enough to be super dangerous or a major hazard unless you're on a short runway, in weather, or something else happens.
 
Flow2706
Posts: 315
Joined: Sat Jan 28, 2017 7:20 pm

Re: EasyJet A321 flew out-of-balance after seated for A320

Sat Oct 16, 2021 7:44 am

bluecrew wrote:
CG's going to be a little north of where it should be, so your stab trim would be significantly off. Uncomfortable, sure, might be a bit sluggish on the rotation, but unless you're operating at the edge of the takeoff envelope it's not great but it's not going to kill you unless you're not paying attention or you have another, major, failure. Probably could cause delayed rotation as the airplane doesn't *smoothly* transition, but with the Airbus FBW it should autotrim to maintain a normal flight envelope pretty quickly. The issues here probably didn't manifest as something overly noticeable to the flight crew, the differences aren't stark enough to be super dangerous or a major hazard unless you're on a short runway, in weather, or something else happens.

This very similar incident happened last year: https://assets.publishing.service.gov.u ... _10-20.pdf In this incident the loading issue was noticed by the crew during takeoff as the aircraft couldn't be rotated until almost maximum back stick and TOGA was applied. So it could definitely be noticeable, even though it seems that this incident didn't create such severe handling issues.
 
bluecrew
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Re: EasyJet A321 flew out-of-balance after seated for A320

Sat Oct 16, 2021 5:23 pm

Flow2706 wrote:
bluecrew wrote:
CG's going to be a little north of where it should be, so your stab trim would be significantly off. Uncomfortable, sure, might be a bit sluggish on the rotation, but unless you're operating at the edge of the takeoff envelope it's not great but it's not going to kill you unless you're not paying attention or you have another, major, failure. Probably could cause delayed rotation as the airplane doesn't *smoothly* transition, but with the Airbus FBW it should autotrim to maintain a normal flight envelope pretty quickly. The issues here probably didn't manifest as something overly noticeable to the flight crew, the differences aren't stark enough to be super dangerous or a major hazard unless you're on a short runway, in weather, or something else happens.

This very similar incident happened last year: https://assets.publishing.service.gov.u ... _10-20.pdf In this incident the loading issue was noticed by the crew during takeoff as the aircraft couldn't be rotated until almost maximum back stick and TOGA was applied. So it could definitely be noticeable, even though it seems that this incident didn't create such severe handling issues.

Well yes - exactly as I said. It created a delayed rotation - the other threat was the 7000 ft runway at Luton in an A321, which has TO performance like an A320 and a DC-8 had a baby.
 
N965UW
Posts: 262
Joined: Wed Jul 29, 2020 11:31 pm

Re: EasyJet A321 flew out-of-balance after seated for A320

Sun Oct 17, 2021 12:19 am

ikolkyo wrote:
Didn't this happen awhile ago? I can't find the thread about it.


Yeah, it was Wizz Air UK last year.

https://airwaysmag.com/airlines/wizz-a3 ... on-mishap/
 
bluecrew
Posts: 120
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Re: EasyJet A321 flew out-of-balance after seated for A320

Sun Oct 17, 2021 4:45 pm

bluecrew wrote:
Flow2706 wrote:
bluecrew wrote:
CG's going to be a little north of where it should be, so your stab trim would be significantly off. Uncomfortable, sure, might be a bit sluggish on the rotation, but unless you're operating at the edge of the takeoff envelope it's not great but it's not going to kill you unless you're not paying attention or you have another, major, failure. Probably could cause delayed rotation as the airplane doesn't *smoothly* transition, but with the Airbus FBW it should autotrim to maintain a normal flight envelope pretty quickly. The issues here probably didn't manifest as something overly noticeable to the flight crew, the differences aren't stark enough to be super dangerous or a major hazard unless you're on a short runway, in weather, or something else happens.

This very similar incident happened last year: https://assets.publishing.service.gov.u ... _10-20.pdf In this incident the loading issue was noticed by the crew during takeoff as the aircraft couldn't be rotated until almost maximum back stick and TOGA was applied. So it could definitely be noticeable, even though it seems that this incident didn't create such severe handling issues.

Well yes - exactly as I said. It created a delayed rotation - the other threat was the 7000 ft runway at Luton in an A321, which has TO performance like an A320 and a DC-8 had a baby.

Apparently I can't edit this lol... more explanation needed:
If you're hitting Vr, smoothly rotating, and the thing is just not lifting the nose off the ground, immediately you know it's probably stabilizer trim or flaps related. The Airbus very loudly and very assertively will alert you if either of those are out of bounds when you advance the thrust levers or when you press TO CONFIG before lining up. If the stab trim is set to what's in the MCDU, you have a very short list of culprits:
1. CG wasn't calculated correctly due to a W&B issue or a load shift (mainly cargo)
2. Your numbers are just entirely wrong - loadsheet error, company pushed the wrong numbers to you or you entered something really wrong on your performance software

On a longer runway you'd just try to trim it out a little until you get some nose up action, get the plane off the ground and I'd return ASAP, because it could be a load shift or something that could get progressively worse and prevent you from keeping the airplane airborne. When you've got 7000 feet to play with and you're blasting off full TOGA with Flaps 3 because A321 lulz, that becomes a little trickier.

Like I said - not good! But also we don't take off blind and with earplugs in, making no inputs or adjustments at all. When you hit Vr and give appropriate back pressure on the sidestick and the nose isn't coming up at all, you know there's something up. And obviously it's not the nose gear.
 
a320fan
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Re: EasyJet A321 flew out-of-balance after seated for A320

Mon Oct 18, 2021 10:07 am

bluecrew wrote:
Flow2706 wrote:
bluecrew wrote:
CG's going to be a little north of where it should be, so your stab trim would be significantly off. Uncomfortable, sure, might be a bit sluggish on the rotation, but unless you're operating at the edge of the takeoff envelope it's not great but it's not going to kill you unless you're not paying attention or you have another, major, failure. Probably could cause delayed rotation as the airplane doesn't *smoothly* transition, but with the Airbus FBW it should autotrim to maintain a normal flight envelope pretty quickly. The issues here probably didn't manifest as something overly noticeable to the flight crew, the differences aren't stark enough to be super dangerous or a major hazard unless you're on a short runway, in weather, or something else happens.

This very similar incident happened last year: https://assets.publishing.service.gov.u ... _10-20.pdf In this incident the loading issue was noticed by the crew during takeoff as the aircraft couldn't be rotated until almost maximum back stick and TOGA was applied. So it could definitely be noticeable, even though it seems that this incident didn't create such severe handling issues.

Well yes - exactly as I said. It created a delayed rotation - the other threat was the 7000 ft runway at Luton in an A321, which has TO performance like an A320 and a DC-8 had a baby.


And this one occurred at Bristol with a 6600ft runway. The A321 is actually quite good regarding field performance. sure it’s no 757 - but it widely flys some long distance holiday routes off relatively short runways.
 
N965UW
Posts: 262
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Re: EasyJet A321 flew out-of-balance after seated for A320

Mon Oct 18, 2021 1:42 pm

a320fan wrote:
bluecrew wrote:
Flow2706 wrote:
This very similar incident happened last year: https://assets.publishing.service.gov.u ... _10-20.pdf In this incident the loading issue was noticed by the crew during takeoff as the aircraft couldn't be rotated until almost maximum back stick and TOGA was applied. So it could definitely be noticeable, even though it seems that this incident didn't create such severe handling issues.

Well yes - exactly as I said. It created a delayed rotation - the other threat was the 7000 ft runway at Luton in an A321, which has TO performance like an A320 and a DC-8 had a baby.


And this one occurred at Bristol with a 6600ft runway. The A321 is actually quite good regarding field performance. sure it’s no 757 - but it widely flys some long distance holiday routes off relatively short runways.


Not to change the subject too much, but I was pleasantly surprised to see AA operating the A321 SNA-JFK nonstop from a 5700ft. runway
 
Lukas757
Posts: 78
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Re: EasyJet A321 flew out-of-balance after seated for A320

Mon Oct 18, 2021 9:46 pm

I always thought that on Airbus FBW aircraft, you just command a roll or pitch rate with the sidestick (at least in normal law). But in that case (wrong CG) you wouldn't feel a difference when rotating, since the FBW would just command more elevator to achieve the pitch change/rotation.
 
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Starlionblue
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Re: EasyJet A321 flew out-of-balance after seated for A320

Tue Oct 19, 2021 12:25 am

Lukas757 wrote:
I always thought that on Airbus FBW aircraft, you just command a roll or pitch rate with the sidestick (at least in normal law). But in that case (wrong CG) you wouldn't feel a difference when rotating, since the FBW would just command more elevator to achieve the pitch change/rotation.


The devil is in the details. ;)

Normal Law is in ground mode until the aircraft is airborne. In Normal Law ground mode, elevator deflection is directly proportional to sidestick deflection, without auto trim.

This means that you do notice CG differences on rotation. For example with an aft CG, the aircraft feels a bit "light" on rotation, and less input is required.

Once the aircraft leaves the ground, Normal Law flight mode is blended in. In Normal Law flight mode pitch control is load factor demand.



To complete the picture, on approach at 100ft (50ft on the A32x?), Normal Law changes from flight mode to flare mode. The stabiliser is frozen and elevator deflection again becomes directly proportional to stick deflection (with some damping). Once on the ground, Normal Law ground mode activates.

It's all very transparent to the pilot, mind you.
 
Flow2706
Posts: 315
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Re: EasyJet A321 flew out-of-balance after seated for A320

Tue Oct 19, 2021 9:43 am

Starlionblue wrote:
Lukas757 wrote:
I always thought that on Airbus FBW aircraft, you just command a roll or pitch rate with the sidestick (at least in normal law). But in that case (wrong CG) you wouldn't feel a difference when rotating, since the FBW would just command more elevator to achieve the pitch change/rotation.


The devil is in the details. ;)

Normal Law is in ground mode until the aircraft is airborne. In Normal Law ground mode, elevator deflection is directly proportional to sidestick deflection, without auto trim.

This means that you do notice CG differences on rotation. For example with an aft CG, the aircraft feels a bit "light" on rotation, and less input is required.

Once the aircraft leaves the ground, Normal Law flight mode is blended in. In Normal Law flight mode pitch control is load factor demand.



To complete the picture, on approach at 100ft (50ft on the A32x?), Normal Law changes from flight mode to flare mode. The stabiliser is frozen and elevator deflection again becomes directly proportional to stick deflection (with some damping). Once on the ground, Normal Law ground mode activates.

It's all very transparent to the pilot, mind you.

To add even more detail to this, on the A320 CEO (on most other Airbus models) this is true. However, one of the differences between A320CEO and A320NEO is the introduction of a rotation law, in which stick deflection controls pitch rate (with gains, to avoid tailstrikes...). This could be one explanation why the Wizz Air crew had more trouble during rotation than the Easyjet crew: the Wizz Air incident involved a "classic" A321, the Easyjet one a NEO. My personal experience is only on A319/320/321CEOs (except one session in a NEO sim), but I heard from colleagues who have flown the NEO that is can be more "crisp" on rotation, not sure if its really that noticeable...
 
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tb727
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Re: EasyJet A321 flew out-of-balance after seated for A320

Wed Oct 20, 2021 12:57 am

Flow2706 wrote:
Starlionblue wrote:
Lukas757 wrote:
I always thought that on Airbus FBW aircraft, you just command a roll or pitch rate with the sidestick (at least in normal law). But in that case (wrong CG) you wouldn't feel a difference when rotating, since the FBW would just command more elevator to achieve the pitch change/rotation.


The devil is in the details. ;)

Normal Law is in ground mode until the aircraft is airborne. In Normal Law ground mode, elevator deflection is directly proportional to sidestick deflection, without auto trim.

This means that you do notice CG differences on rotation. For example with an aft CG, the aircraft feels a bit "light" on rotation, and less input is required.

Once the aircraft leaves the ground, Normal Law flight mode is blended in. In Normal Law flight mode pitch control is load factor demand.



To complete the picture, on approach at 100ft (50ft on the A32x?), Normal Law changes from flight mode to flare mode. The stabiliser is frozen and elevator deflection again becomes directly proportional to stick deflection (with some damping). Once on the ground, Normal Law ground mode activates.

It's all very transparent to the pilot, mind you.

To add even more detail to this, on the A320 CEO (on most other Airbus models) this is true. However, one of the differences between A320CEO and A320NEO is the introduction of a rotation law, in which stick deflection controls pitch rate (with gains, to avoid tailstrikes...). This could be one explanation why the Wizz Air crew had more trouble during rotation than the Easyjet crew: the Wizz Air incident involved a "classic" A321, the Easyjet one a NEO. My personal experience is only on A319/320/321CEOs (except one session in a NEO sim), but I heard from colleagues who have flown the NEO that is can be more "crisp" on rotation, not sure if its really that noticeable...


NEO's are very crisp, as you say, on rotation. As it blends from ground mode to Normal Law it seems to be overly sensitive and light. It really gets your attention the first time you fly it. We don't have the 321NEO yet but when we do get them I am sure special attention will have to be given for tailstrike awareness compared to the CEO version.
 
bluecrew
Posts: 120
Joined: Sun Apr 20, 2014 3:13 am

Re: EasyJet A321 flew out-of-balance after seated for A320

Wed Oct 20, 2021 4:04 am

Flow2706 wrote:
Starlionblue wrote:
Lukas757 wrote:
I always thought that on Airbus FBW aircraft, you just command a roll or pitch rate with the sidestick (at least in normal law). But in that case (wrong CG) you wouldn't feel a difference when rotating, since the FBW would just command more elevator to achieve the pitch change/rotation.


The devil is in the details. ;)

Normal Law is in ground mode until the aircraft is airborne. In Normal Law ground mode, elevator deflection is directly proportional to sidestick deflection, without auto trim.

This means that you do notice CG differences on rotation. For example with an aft CG, the aircraft feels a bit "light" on rotation, and less input is required.

Once the aircraft leaves the ground, Normal Law flight mode is blended in. In Normal Law flight mode pitch control is load factor demand.



To complete the picture, on approach at 100ft (50ft on the A32x?), Normal Law changes from flight mode to flare mode. The stabiliser is frozen and elevator deflection again becomes directly proportional to stick deflection (with some damping). Once on the ground, Normal Law ground mode activates.

It's all very transparent to the pilot, mind you.

To add even more detail to this, on the A320 CEO (on most other Airbus models) this is true. However, one of the differences between A320CEO and A320NEO is the introduction of a rotation law, in which stick deflection controls pitch rate (with gains, to avoid tailstrikes...). This could be one explanation why the Wizz Air crew had more trouble during rotation than the Easyjet crew: the Wizz Air incident involved a "classic" A321, the Easyjet one a NEO. My personal experience is only on A319/320/321CEOs (except one session in a NEO sim), but I heard from colleagues who have flown the NEO that is can be more "crisp" on rotation, not sure if its really that noticeable...

This is interesting... never flown the NEO personally or the A321 either... not moving to the bus lol. I did fly clapped out A319s and A320s in a galaxy far far away though, back during the dark regional times.
I think I've forgotten more about the bus than I ever knew, but this sounds intriguing. I've seen many... undertrained?... folks overrotate even an A319, so this seems like it's probably a great change.

I'm still trying to wrap my head around the term "DUAL COOL" :lol:

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