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A320 Flap3 landing to save fuel

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A320 Flap3 landing to save fuel

Old 18th Jun 2020, 22:36
  #21 (permalink)  
 
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Originally Posted by RexBanner View Post
Well when you’re talking about making a saving of 8kgs but then you then wipe out that saving by taxying a much further distance (think E vs FR at EGKK for instance) then yes it is very relevant. I think the braking to start causing whiplash would be extreme indeed (never have I once experienced it as a passenger or as a crew member and I operate/pax into EGJJ a lot).
Looking at Gatwick, E vs FR is exactly what I'd consider negligible for fuel burn, after having spent a few hours up at altitude burning 100lb a minute. It adds what, an extra 45 seconds to the flight? How does that compare to not getting that step climb at exactly the right spot, or flying 2000ft higher or lower for turbulence? Get to the gate too soon, and the ground staff isn't ready anyway

As I said earlier, my opinion is that the taxi fuel saving there is academic.

Last edited by Check Airman; 18th Jun 2020 at 22:49.
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Old 18th Jun 2020, 22:47
  #22 (permalink)  
 
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Donít want to start getting too far into it or splitting hairs but regular visitors to Gatwick will know that the difference between making E or FR can easily add quite a significant amount of time onto your taxy time depending on the traffic situation. I completely agree with your point that itís peanuts but if youíre interested in the minutiae of specifically choosing Flap 3 in order to save 8kg fuel but then you miss a turnoff that then costs you more than 8kgs fuel in the process then thatís missing the bigger picture IMHO.

Last edited by RexBanner; 18th Jun 2020 at 22:58.
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Old 18th Jun 2020, 23:00
  #23 (permalink)  
 
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Originally Posted by RexBanner View Post
Donít want to start getting too far into it or splitting hairs but regular visitors to Gatwick will know that the difference between making E or FR can easily add quite a significant amount of time onto your taxy time depending on the traffic situation. I completely agree with your point that itís peanuts but if youíre interested in the minutiae of specifically choosing Flap 3 in order to save 8kg fuel but then you miss a turnoff that then costs you more than 8kgs fuel in the process then thatís missing the bigger picture IMHO.
Never been to LGW, but agree with your last point. If opting for F3 leads to a significantly longer taxi time, youíve lost the plot.
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Old 18th Jun 2020, 23:02
  #24 (permalink)  
 
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The difficulty is handing. Flap 3 often feels pitchy and rolls quite a lot in turbulence on a warm air day. So landing at this high elevation with a 3.5 degree slope would be flap full for me. You might have the runway performance but you still need a stable approach.
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Old 18th Jun 2020, 23:31
  #25 (permalink)  

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vilas I'm a great fan of not burning more fuel than needed. Tried F3 when it made sense, now and then.

Wise opinions above already, it's a very hard task to calculate whether or not will F3 bring real fuel savings (extended taxi time), or burn more money on reversers use et al. The opinion I like the most, is to educate the pilot pool and give them the option. Not to force it into standard practice.

There is one case I know of, where it would be a good and reasonable STANDARD option, In LIMC/MXP, 98 % of the time the landing direction is northbound. A large LoCo using predominantly A319s is based in the northern terminal T2 https://www.google.com/maps/search/M.../data=!3m1!1e3. Plain to see, using F3, idle REV, no ABRK will get you to the gate quickest, cheapest and greenest.

In VEIM the taxi configuration looks inviting. My first choice would be NO, not as a standard. Mostly due to steeper glide, crew proficiency must be considered. As an educated choice, why not, I would happily let the FO fly it.


Check Airman One minute taxi time burns 11 kgs of fuel (+2 for APU), completely no strings attached. Engine-hours also a factor if. The alleged F3 savings on approach are 6-8 kgs, and people are discussing the latter.
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Old 19th Jun 2020, 00:34
  #26 (permalink)  
 
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I believe we’ve been talking about the A319s/A320s in general here, what about the A321s? We don’t have A321s in our fleet, neither have I flown one. I for one don’t see tailstrike as a significant risk on the A319s/A320s, but out of curiosity, any real risks or difference when doing it on the A321?

Aside from fuel savings, another good reason to get well acquainted with Flaps 3 landings whenever you can is you never know when you’ll have to do one in Direct Law one day.
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Old 19th Jun 2020, 01:03
  #27 (permalink)  
 
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Originally Posted by dream747 View Post
I believe we’ve been talking about the A319s/A320s in general here, what about the A321s? We don’t have A321s in our fleet, neither have I flown one. I for one don’t see tailstrike as a significant risk on the A319s/A320s, but out of curiosity, any real risks or difference when doing it on the A321?

Aside from fuel savings, another good reason to get well acquainted with Flaps 3 landings whenever you can is you never know when you’ll have to do one in Direct Law one day.
The 321 is odd in that the tail clearance is ever so slightly better with F3. Still a higher approach speed though. Easiest of the 3 to land, in my opinion. I haven't flown the A318.

FlightDetent I do my part by not starting the APU unreasonably early.

Last edited by Check Airman; 19th Jun 2020 at 01:27.
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Old 19th Jun 2020, 01:56
  #28 (permalink)  
 
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I did an analysis many years ago on this exact question. The brake wear is a negligible item as the brakes, while expensive, last a very long time. There is some reduction in flap drive wear costs associated with Config.3 landings. The kicker is the tire costs - 10% greater than with a Config. Full landing. Back then, the tire wear was the same as the fuel saving. With the low cost of fuel now I would be pretty certain that it costs more overall to land Config. 3 than Config Full. YMMV.
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Old 19th Jun 2020, 07:46
  #29 (permalink)  
 
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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....
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Old 19th Jun 2020, 07:51
  #30 (permalink)  
 
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Originally Posted by Check Airman View Post
At my US company, flap 3 is ďencouragedĒ but most people go with full. Itís at the discretion of the PF. My preference in your situation would be full. We do a few approaches to places where the glide slope is a bit steeper (maybe 3.3, I think), and flap 3 still works fine. I think the major hurdle would be getting stabilised earlier.

That said, 8kg of fuel is less than a rounding error on the gauges. The fuel bowser typically delivers a bit more than the number thatís dialled in. On my last flight, we were over fuelled by about 25 times the 8kg weíre thought to save with flaps 3.
The fact that you can't measure it doesn't mean it doesn't exist.
It will be measurable if a consequent number of pilots do this type of eco-flying.
(And, of course, if the fuel saving is not counterbalanced by longer taxi-in and/or more use of reverse thrust..)
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Old 19th Jun 2020, 08:01
  #31 (permalink)  
 
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Originally Posted by vilas View Post
Hi everyone!
An issue is being discussed in an A320 Asian LCC regarding doing Flap3 landing instead of Flaps full. Actually all are doing it to save some 8kg fuel per landing.The issue is with an airfield with elevation of 2540ft and runway length of 2746mtr. there is an ILS but the glide path is 3.5į. I want to know if there are any European and US carriers who do it. If so are their any conditions when to do and when not to do. Opinions with reasoning are welcome.
Thanks
Hi vilas,

European flag carrier. We used to have a stable approach criteria being not exceeding 1200 ft/min below 1000 ft AAL but that was eventually changed a few years back to the aircraft established on the vertical path with no specific RoD, hence the above combination would be possible, RoD wise.
We do not have set limitations for flaps config selection for CAT A and B aerodromes ; basically you choose whatever makes sense trying to save fuel as much as possible.
With the above scenario, unless it would be a CAT C aerodrome with specific instructions, I guess 90% + of the crew would elect CONF FULL, especially in hot weather.
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Old 19th Jun 2020, 08:24
  #32 (permalink)  

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Originally Posted by 172_driver View Post
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....
Different landscape, really. Immediate return OEI: (*)
- ISA SL -> up to 88 tonnes the standard flap is full.
- 4000 ft @ 40į -> 77 max for standard flap full (77 = MTOW).

F3 is awkward. But you have a point, perhaps one day everyone will switch over, most likely for noise. As witnessed by the valuable insight here, there is no practical benefit (**) although for a narrowly minded KPIs a case can be made and had been repeatedly.

IIRC on IAE engines the angle for flaps full was increased to a greater deflection, to allow higher N1 in order to assure TOGA engine spool-up characteristics. Heard it here, FCOM confirms the geometry.

(*) Airbus cheating again, QRH: MAX WEIGHT FOR LANDING IN CONF FULL again has data for CS-25 gradient 2,1% (non LVO), whereas in the real-life 2,5% is needed to match PANS-OPS.
(**) if approaching stable approach gate 1000 and too fast, a dirty trick is to change for F3 and move the goalposts. Let's talk what's wrong with some FDM / FOQA concepts ..., rather not.

Last edited by FlightDetent; 19th Jun 2020 at 08:39.
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Old 19th Jun 2020, 09:44
  #33 (permalink)  
 
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Yawn... you lot need to get back to work.
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Old 19th Jun 2020, 11:01
  #34 (permalink)  
 
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Originally Posted by 1201alarm View Post
Another big pro F3 is practice: many abnormals require a F3 landing, so you want to be current and skilled in them, you want to be used to the higher pitch picture when going visual, sounds pretty bad to me in the stress of an abnormal to fly the bird the first time in F3. That is why I try to make regular F3 landings, when appropriate according to the criteria above..
Heard that line trotted out before. It's tosh, quite frankly. If you're doing a CONF3 approach due to ECAM, by definition it won't be a "normal" CONF3 approach. The approach speed will be higher due to a Vref correction so the "picture" won't look the same as in a normal CONF3 approach anyway, you'll probably be dealing with other configuration issues which mean the handling won't be the same as in normal ops etc.
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Old 19th Jun 2020, 11:38
  #35 (permalink)  
 
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Originally Posted by Rt Hon Jim Hacker MP View Post
Could you advise which airfield? Can then run it through FS to see how the settings affect landing distance.
FS?? What is that?
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Old 19th Jun 2020, 11:51
  #36 (permalink)  
 
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Originally Posted by Flapsupbedsdown View Post
FS?? What is that?
I believe it refers to FlySmart. The Airbus EFB.
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Old 19th Jun 2020, 13:08
  #37 (permalink)  
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To put it together Flap3 does save fuel. The pros and cons for steep approach
1. In A320 Flap3 landing is not an issue because Flap3 is mandatory for abnormal landings.
2. Landing distance is not an issue as Flap3 takes appx.150mtrs extra. Also the reference WT is MLW which may not be the case mostly.
4. From stabilization point of view only the ground speed can be limiting because in turn it will breach ROD criteria.
5. This should only come in play with tailwind which also the most penalizing for landing distance.
For stabilization tailwind may have to be avoided and opposite runway can be chosen if possible. Off course fuel saving can be done on another day.
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Old 19th Jun 2020, 13:50
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We have a procedure - wind shear precautions - which is used when wind shear probability may exist, but doesnít warrant avoidance. This procedure, among other things, requires a Flap3 landing. I recall one flight where it was appropriate to use the precautions and told the FO (who was PF) that he would do a F3 landing. He looked at me bug eyed. (That isnít what we want to see from a fully qualified pilot performing a normal procedure.)

Our fleet encourages F3 landing for fuel savings and reduced noise footprint. From my experience, less than 5% of pilots fly them with any regularity.



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Old 19th Jun 2020, 14:19
  #39 (permalink)  
 
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Originally Posted by 172_driver View Post
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....
Flaps full is more stable, and the default landing config is full- flap 3 means increased workload
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Old 19th Jun 2020, 14:34
  #40 (permalink)  
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We have a procedure - wind shear precautions - which is used when wind shear probability may exist, but doesnít warrant avoidance. This procedure, among other things, requires a Flap3 landing.
CM
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
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