A320 Flap3 landing to save fuel
A differing opinion
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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From my experience, F-3 gives better handling and response in turbulence, than using F-FULL (less drag with F-3).
FCTM SUPPLEMENTARY PROCEDURES ADVERSE WEATHER
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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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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!
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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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
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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I’m also not a fan of medium unless it’s necessary. It’s 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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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 “brake maintenance packages”, I’d guess it’s got something to do with it.
My thoughts exactly. I’d rather have low and then use manual braking to make my turn-off
My thoughts exactly. I’d rather have low and then use manual braking to make my turn-off
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.
Last edited by vilas; 8th Jul 2020 at 13:41.
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Everything depends on the airline and the maintenance packages they use.
Airline A might find it cheaper to hammer the brakes instead of the engines. Airline B might be vice-versa and prefer flap full and max reverse. Airline C might be using different brake material.
The reality is that 90% of carbon brake wear happens on taxi-out.
Airline A might find it cheaper to hammer the brakes instead of the engines. Airline B might be vice-versa and prefer flap full and max reverse. Airline C might be using different brake material.
The reality is that 90% of carbon brake wear happens on taxi-out.
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Originally Posted by Fursty Ferret
The reality is that 90% of carbon brake wear happens on taxi-out.
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Airbus considers fuel Vs brakes oxidation and replacement. According to them economy from Flap3 landing is when you use AB low. In medium or overtaking manually results in high temperatures and repeated exposure to high temperature leads to thermal oxidation and may be fracture requiring replacement which overtakes the cost of fuel saved.
Airbus considers fuel Vs brakes oxidation and replacement. According to them economy from Flap3 landing is when you use AB low. In medium or overtaking manually results in high temperatures and repeated exposure to high temperature leads to thermal oxidation and may be fracture requiring replacement which overtakes the cost of fuel saved.
Apparently more related to high wear at lower temperatures.
https://code7700.com/pdfs/carbon_brakes_airbus.pdf
https://code7700.com/pdfs/carbon_brakes_airbus.pdf
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Thank you for your input vilas.
hans bringer: Interesting article. Thanks for sharing. It seems like it is a matter of both, actually. Both low temperatures and brake applications seems to be the two factors with more importance regarding brake wear.
It also seems I was screwing it up with these brake temp thing; I HATE the sound of brake fans left running thru the turnaround, and I always found that if I turned it on at the start of the pushback I’d be with cool enough (100-ish) brakes when taking off. This, of course, means that I’ve been taxiing out with the brakes at its highest wear rate zone (ours are MB if I recall). Food for thought...
As a side question: Is the brake manufacturer the one on the wheel rim? Or can the rims and the brakes be from different manufacturers?
hans bringer: Interesting article. Thanks for sharing. It seems like it is a matter of both, actually. Both low temperatures and brake applications seems to be the two factors with more importance regarding brake wear.
It also seems I was screwing it up with these brake temp thing; I HATE the sound of brake fans left running thru the turnaround, and I always found that if I turned it on at the start of the pushback I’d be with cool enough (100-ish) brakes when taking off. This, of course, means that I’ve been taxiing out with the brakes at its highest wear rate zone (ours are MB if I recall). Food for thought...
As a side question: Is the brake manufacturer the one on the wheel rim? Or can the rims and the brakes be from different manufacturers?
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Everything depends on the airline and the maintenance packages they use.
Airline A might find it cheaper to hammer the brakes instead of the engines. Airline B might be vice-versa and prefer flap full and max reverse. Airline C might be using different brake material.
The reality is that 90% of carbon brake wear happens on taxi-out.
Airline A might find it cheaper to hammer the brakes instead of the engines. Airline B might be vice-versa and prefer flap full and max reverse. Airline C might be using different brake material.
The reality is that 90% of carbon brake wear happens on taxi-out.
I believe I speak for the majority when I say flap 30 is the norm on the 737, flap 40 only for performance. My friends on the 320 seem to prefer flap full over flap 3 (..is that how you say it? or config 3?) as standard. I have always wondered why it's become like that....
)From memory the B737 has 8 or 9 flap lever positions: 1,2,5,10,15,25,30,40. (can't remember if there is also a 0.5° position?).
Airbus FBW family has just 4 flap lever positions. I imagine the Airbus design engineers calculated that they didn't need so many config options, maybe as a result of the wing or the FBW, so they could massively simplify the system and the flight operation? Normal landings are with Flap full, and Flap three used on very turbulent days.
I think it is getting a bit desperate when crews are being asked to modify their landing performance just to save 8kg of fuel. Of course it could theoretically add up over a year, but that is more a spreadsheet artifact, and as Check Airman points out; that sort of small amount can easily get lost in the 'noise'. Just get the marketing department to earn their salary and work harder to attract more passengers !
I mean, operators could just as easily demand that pilots' flight bags weigh no more than X kg, or that crew themselves weigh no more than X !! Well, it would theoretically save fuel.......
On Airbus I think four positions: 'Low, Medium, High (and Max)' autobrake would have been helpful on the A320 family; to give us three normal autobraking options instead of only two: with the new Medium being slightly less than it is now, and the new High being slightly more than Medium is now. There is a space on the panel for one extra PB, so it might have been considered?
As in 1-2-3-max-RTO? Could not agree more.
