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A320 Flap3 landing to save fuel

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A320 Flap3 landing to save fuel

Old 19th Jun 2020, 17:00
  #41 (permalink)  
 
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A differing opinion

Originally Posted by Check Airman View Post
Flaps full is more stable, and the default landing config is full- flap 3 means increased workload
Has anyone else noticed in the A320, that when selecting F-FULL which generally occurs at about 1200ft AGL, there is ~1.0 deg (or more) pitch up? This means that, when hand-flying an approach and to remain on the required vertical path, a counter-action is required by the PF.
If AP is engaged with FPA -x.x (say -3.0) for vertical guidance, then after F-FULL selected, the FPA needs to be adjusted to -4.0 to retain the correct vertical path. This would be an increase in work-load particularly approaching the 1000ft stabile approach criteria, not experienced with F-3 approaches.

Quote: It is a bit paradoxical in Airbus that Flap3 gives better performance in wind sheer but Flap full gives better handling in turbulence. It's due reduced gain in flaps full. Controls are more sensitive in Flap3.

Can someone provide the reference to the FBW architecture for reduced gain in F-FULL, which would make F-FULL less sensitive than F-3? From my experience, F-3 gives better handling and response in turbulence, than using F-FULL (less drag with F-3).




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Old 20th Jun 2020, 08:33
  #42 (permalink)  
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From my experience, F-3 gives better handling and response in turbulence, than using F-FULL (less drag with F-3).
That's why I said paradoxical
FCTM SUPPLEMENTARY PROCEDURES ADVERSE WEATHER

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Old 21st Jun 2020, 09:44
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Originally Posted by Weapons Grade View Post
Can someone provide the reference to the FBW architecture for reduced gain in F-FULL, which would make F-FULL less sensitive than F-3? From my experience, F-3 gives better handling and response in turbulence, than using F-FULL (less drag with F-3).
Hi Weapons Grade,

This picture Roll Kinematics (from an incident report of A320 with handling difficulties in Hong Kong many years ago) shows the change in roll spoiler response with handle at Flaps Full.

Initially for roll orders up to about 7 degrees, the spoilers are far less responsive (but are activated 3 degrees earlier than CONF 3)
Beyond 7 degrees and up to about 11 degrees of roll order, the spoilers are a bit more responsive but still only about half that of CONF 3. (11 degrees of roll order v 6 degrees of roll order for 10 degrees of spoiler deflection)
Beyond 11 degrees the spoilers become more sensitive and full authority is restored at 20 degrees roll order.

I can't find the report just yet, (see Aviation Safety Net) but from memory Airbus changed the ECAM procedure.
"APPR PROC S/F JAMMED PROC APPLY FOR LDG (IF FLAPS ≤ 3) USE FLAP 3
This line is replaced by “FOR LDG : USE FLAP 3” when CONF 3 is selected, as a reminder
FLAPS (IF FLAPS>3) KEEP CONF FULL."

Last edited by Goldenrivett; 21st Jun 2020 at 13:09. Reason: extra info
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Old 21st Jun 2020, 10:19
  #44 (permalink)  
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Thank you Golden I wanted to post that but felt lazy.
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Old 21st Jun 2020, 14:55
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What about brakes and tyre wear?
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Old 22nd Jun 2020, 09:48
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Interesting information about landing gear warnings
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Old 6th Jul 2020, 00:37
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In our company we are encouraged to land Conf 3, it is our first option to land, even on a wet (but not contaminated) runway, provided we run a calculation with runway condition “medium to poor” and take no credit for reverse. However, we do have some high altitude airports; main base is at 8300ft, our most frequent destination is at 7000, and we have everything between those and airports right at MSL. I do try to save fuel when possible (part of the job description now, I suppose), but I try to put common sense on top, so far as decision making goes, and I’ve tried to made it simple for myself.

So here goes: land with Conf 3 (+ idle rev) if no particular weather phenomenon present, I.e, no tailwind, no massive shower, no chance of shear and, if landing at one of those high alt airports (read those two mentioned above) resulting Vapp no higher than 140 (mainly for the GS/VS relation mentioned above, and also to take care of the brake temp, since our turnarounds are short). I’ll even land conf 3 with a wet (but not contaminated) runway, if no other relevant factor is present (no high winds, no heavy shower). However: runway with active heavy rain showers (we fly in the Caribbean) or runway too wet (as in “massive rain shower just ended”) will see me use conf full + max rev. Tailwind? Too heavy? Atmosphere too bumpy (like on hot days)? Conf full is my choice.

I do have a nitpick, which I will present to you here for judgement/correction/confirmation, and that is the abrk setting. Company says this is the first item to be modified in the landing conf (before flaps and rev, in that order) for $ome rea$on I $u$pect, which would mean that if I choose to land with flaps full + rev, it’s because I already have abrk on medium. However, when landing in seriously wet runways I use conf full, rev but abrk on low. My reason for this is that I know (because of Lauda Air 767) that reversers destroy lift, and abrk at medium will sometimes make controllability a bit harder once on ground (on one occasion I even had to disengage it as it made the airplane veer left and correcting with pedals wasn’t enough). Abrk low, in my experience, will see the airplane roll down nice and easy with no weird pulls to either side and control will be easier. Any comments on this practice?

Regards!
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Old 6th Jul 2020, 05:04
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Escape Path
Without abnormality Conf3 landing is for fuel saving. Two other factors compet with this are maintenance of reverse and brakes wear. According to an Airbus study on the subject brake oxidation and replacement cost can nullify fuel saving. Therefore the ideal combination is Conf3, Reverse idle and A/B low. If this combination doesn't suit the landing distance then it is modified in the same order. First go for Flap full if further reduction in LD is required then use reverse full and higher A/B is the last priority. In slippery conditions A/B is better for symmetrical application. In your example could be one side brakes catching. Regards
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Old 6th Jul 2020, 08:49
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Iím also not a fan of medium unless itís necessary. Itís a bit too aggressive. At times, low is too slow to act though. I do like that in the NEOs, low gives a bit better performance. Just right, I think.
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Old 7th Jul 2020, 17:32
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Originally Posted by vilas View Post
Escape Path
If this combination doesn't suit the landing distance then it is modified in the same order. First go for Flap full if further reduction in LD is required then use reverse full and higher A/B is the last priority.
Thank you for your insight vilas. Funny thing, our company asks us to modify conf almost the other way around: Abrk, then flaps, then rev. I know there are different ďbrake maintenance packagesĒ, Iíd guess itís got something to do with it.

Originally Posted by Check Airman View Post
Iím also not a fan of medium unless itís necessary. Itís a bit too aggressive. At times, low is too slow to act though
My thoughts exactly. Iíd rather have low and then use manual braking to make my turn-off
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Old 7th Jul 2020, 18:20
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Originally Posted by Escape Path View Post
Thank you for your insight vilas. Funny thing, our company asks us to modify conf almost the other way around: Abrk, then flaps, then rev. I know there are different ďbrake maintenance packagesĒ, Iíd guess itís got something to do with it.
My thoughts exactly. Iíd rather have low and then use manual braking to make my turn-off
Actually something similar is happening in Indian context. One carrier is retaining flap3 but selecting A/B medium to stay within FLD. But Airbus doesn't recommend that. I will check with the airline to see
​​ if they have some other factor to do so. Also Airbus doesn't recommend taking.over manual braking from low i.e. from fuel saving point.
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