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A320 Flap3 landing to save fuel

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A320 Flap3 landing to save fuel

Old 18th Jun 2020, 17:16
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A320 Flap3 landing to save fuel

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 3.5°. 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
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Old 18th Jun 2020, 17:36
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Could you advise which airfield? Can then run it through FS to see how the settings affect landing distance.
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Old 18th Jun 2020, 17:53
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At my US company, flap 3 is “encouraged” but most people go with full. It’s 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 that’s dialled in. On my last flight, we were over fuelled by about 25 times the 8kg we’re thought to save with flaps 3.
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Old 18th Jun 2020, 18:12
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European LCC, our standard is flaps full.
But when we want to train, find it operationally relevant or if we just want to have some fun, we fly flaps 3.
(Single engine, its up to the pilots as well if we land with flaps full or flaps 3)
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Old 18th Jun 2020, 18:23
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Well, we do a landing distance required performance calculation prior to every approach. The result from the EFB has an extra safety factor margin of 15% added. So, provided that Asian LCC does likewise, the EFB result is OK and the approach stable, why not? Flying a Flap 3 approach and landing in the A320 produces a lower noise footprint, saves 9kgs fuel and is recommended by Airbus. Also, we are reminded of our social and environmental responsibility to try and fly as efficiently as possible thereby reducing CO2 emissions, Penguins lives matter too.
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Old 18th Jun 2020, 18:33
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It's VEIM. The landing distance is not a problem. Difference between Full and Flap3 is about 150mtrs. I was presented with data of some landings about the ground speed and ROD. invariably in all landings the GS was 150 to 160 kts and.ROD was greater than 1000ft/mt. and unstable approach. Even for 3.5 Glideslope unless the Ground speed is in excess of 170kt the ROD shouldn't be that high. Except landing in tailwind what other reason could be there? And why would anyone land with Flap3 with that Ground speed?
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Old 18th Jun 2020, 18:49
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According to the FAA ROD table, a 3.5 degree Slope at 150kt will be 925fpm. Passing 3500ft MSL, if you say the Vapp can get up to 160, it wouldn’t take much to get a VS over 1000fpm- but that wouldn’t be unstable in this case.

I guess the TAS and the slope is causing the higher ROD. Flap 3 wouldn’t be my first choice, but it’s doable, I’d think.

[img]blob:https://www.pprune.org/8ad432d7-3a41-4622-816d-11bb1857db4e[/img]

http://code7700.com/cdfa.htm
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Old 18th Jun 2020, 19:02
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Any idea if the terrain on approach is sloping down towards the threshold? Could it be one of those places which has a lot of thermal activity due to trees/crops?
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Old 18th Jun 2020, 19:30
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Look at the distances and where you want to turn off. If you have to go to the end of the runway, F3 may be useful. If there is a 10 HWC, F3 landing distance is going to be similar to FF with no wind. The idea behind the fuel savings is that in a big company, all those 8kgs add up to a significant $ sum over a year. If you are landing on the limits, then FF allows a bit more room for error.
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Old 18th Jun 2020, 19:31
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Hi Vilas,
My old company used to 'encourage' F3 landings, quoting fuel saving as a justification. But they were gracious enough to accept that safety came first. So if you are not happy, use F Full. I was never convinced by the fuel saving argument - from what I could find out, the comparison was done for F3 vs Full from 3000 ft on the glideslope - this may well have generated some fuel saving. But doing the approach in F3 and going F Full in time to meet your companies' stabilisation criteria is unlikely to save much fuel at all. The beancounters say that over a fleet of 'x' aircraft, each flying 'y' times per day that generates 'z' dollars savings. So if you don't fancy F3 into a particular airfield on a particular day, that won't dent their figures too much. Be safe. If you are the Commander - take command and do what is safest.
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Old 18th Jun 2020, 19:43
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Alternatively, if the general preference is for F3, you could always recommend Full for the field in question.
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Old 18th Jun 2020, 20:15
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Probably all comes down to the type of brakes maintenance contract. “Fixed Price” or “On Condition”. It’s a funny old world.
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Old 18th Jun 2020, 20:28
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Originally Posted by Molesworth View Post
Hi Vilas,
My old company used to 'encourage' F3 landings, quoting fuel saving as a justification. But they were gracious enough to accept that safety came first. So if you are not happy, use F Full. I was never convinced by the fuel saving argument - from what I could find out, the comparison was done for F3 vs Full from 3000 ft on the glideslope - this may well have generated some fuel saving. But doing the approach in F3 and going F Full in time to meet your companies' stabilisation criteria is unlikely to save much fuel at all. The beancounters say that over a fleet of 'x' aircraft, each flying 'y' times per day that generates 'z' dollars savings. So if you don't fancy F3 into a particular airfield on a particular day, that won't dent their figures too much. Be safe. If you are the Commander - take command and do what is safest.
Flaps full at 3000ft?!?! I guess that’s one way to ensure you’re stable. From non-scientific observation, I’d guess most people in my company don’t get to full until 1200-1500, so that halves the fuel saving.
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Old 18th Jun 2020, 20:38
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The other thing to bear in mind is how much extra fuel you’re burning from missing the exit that you otherwise would have made on the landing roll by using Flap Full. These things are never in isolation.
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Old 18th Jun 2020, 20:38
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We used to get continuous hassle from management that our little base didn’t have a big uptake on F3 landings and S/E taxi in.

What they failed to realise was that using F3 would usually involve rolling to the very end and about a 900M taxi in rather than a sharp 90 (not high speed) straight onto the apron.

Have those flights into VEIM been training flights? Could be a factor.

OFDM is a good tool but needs the human touch to make proper sense of the data.

You beat me to it Rex....
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Old 18th Jun 2020, 20:44
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Originally Posted by Rt Hon Jim Hacker MP View Post
You beat me to it Rex....
quick on the draw but to be fair you illustrated the point better.
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Old 18th Jun 2020, 21:16
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I'm all for saving fuel, but isn't it getting a bit academic when we're talking about fuel burn to taxi a few feet when taking one exit vs another? Not to mention the potential lawsuits because of whiplash as people slam on the brakes to make the first exit?
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Old 18th Jun 2020, 21:42
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F3 or Full is judgement of the crew where I fly the A320. Following things to consider:

Pro Full factors: runway short, wet, contaminated, aircraft very light, ab-initio FO at his very beginning of training, exceptionally when single engine and GA gradient is no factor and runway is short, nearer runway turnoff reachable, speed advisory until late in final (e.g. 160 to 4) to still make it stable upon handbooks gate, lazy pilot

Pro F3 factors: fuel saving (reduction of stable N1 is clearly there, so there must be some markable saving), less noise, long runway, long rollout, standard when single engine, possible windshear (once you go around you're in F2 instead of F3, in WS escape you're in F3 iso Full).

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.

Stabilisation is no issue, the A320 is always stable at 1000' when dropping the gear at (10 x GS + threshold alt) for Full, add 300ft for F3.
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Old 18th Jun 2020, 22:18
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Originally Posted by Check Airman View Post
I'm all for saving fuel, but isn't it getting a bit academic when we're talking about fuel burn to taxi a few feet when taking one exit vs another? Not to mention the potential lawsuits because of whiplash as people slam on the brakes to make the first exit?
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).
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Old 18th Jun 2020, 22:25
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I can think of one company which only allows you to land with flaps 3 after you have accumulated certain experience on type. Due to the unusual attitude and higher than normal ROD, there are the inherent risks of a hard landing due to a misjudged flare or even a tailstrike. I have never been close to controllability becoming an issue at the lower speed with flaps full, so the primary arguments in favour remain noise and fuel consumption. 8 kg per flight may not sound significant, but over the lifetime of the aircraft it adds up to quite a number.

As for approach stabilisation, using the flaps as a brake is not a good idea because you will quickly wreck the bearings in their actuators. Unlike the 737 with its massive screwjacks for the flaps, the A320 uses a system of arm actuators which is light and compact but also heavily reliant on said bearings. When the bearings are worn, you can easily feel it with some nasty vibration appearing once the flaps are down.
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