Airbus - Flap FULL or Flap 3??
 

General question:

Under what circumstances would you use Flap 3 for landing as opposed to Flap FULL? And why??

Obviously this question would apply to any aircraft where you have a choice of landing flap settings. Normally most people I have seen will use Flap 3 for gusty or turbulent conditions. However, I am unsure as to the philosophy behind this as we fly the approach 5 knots faster but still 5 knots above VLS (wind conditions permitting). So why use Flap 3??

Any thoughts welcome.................

that's right, when u insert datas in the FMS, there is full flaps or 3 flaps choice.
any idea?

Dartagnan,
What is your current level of experience?

Our company policy is that Flap Full will always be used unless an abnormal procedure requires the use of Flap 3. I should be interested in whether other companies routinely permit crews to use Flap 3 for landing and if so under what circumstances.

I lean towards the idea of there being no real advantage in the use of Flap 3. The only thing I can think of is that it would result in a slightly higher nose attitude which may be of slight benefit if wind conditions dictate the use of a particularly high VAPP. Other than that, what does it do for you??

My company does not exclude the use of flaps3. But flaps FULL is recommended under normal conditions. No guidance w.r.t. use of flaps 3 for LDG in normal ops is provided.

However I recall from Airbus Industrie FCOM that flaps 3 is recommended in case of reported windshear and/or severe turbulence during the apch.
I think energy is the keyword here. You have better G/A performance because Flaps 2 has a better L/D ratio than Flaps 3 (read: more efficient wing). Same for the balked landing obviously. This provides you with better windshear escape capabilities and gust recovery.
You could also argue that flying at higher speeds (5-6 knots normally) provides you with better stability but I would imagine that this is very marginal.

Personally on a very gusty day, I will have flaps 3 anytime. Provided stopping performance is not limiting.


I think there are some companies using Flaps3 as a standard for LDG because of economy (noise and fuel savings). I suppose they operate on long runways where there is no cost of braking/reverse.

The argument for CONF 3 landings in strong crosswinds and severe turbulence is that the aircraft has more energy and is in a lower drag configuration. The increased approach speeds will also decrease the required crab angle in crosswinds. Higher airspeeds increase control effectiveness and response.

That said, the only FCOM reference I could find for CONF 3 landings is this:

LANDING
Configuration FULL, or 3, can be used.
However, Configuration 3 provides more energy and less drag.

FCOM 3.4.91

My company doesn't mention the use of CONF 3 for landing in our ops manuals but I've flown with lots of people who use it in strong crosswinds. I've used it myself a few times but to be honest, I couldn't really see any real benefit gained.

I was led to believe that roll response was 'crisper' in Flap 3 than Flap Full, hence giving better handling at the expense of landing distance. If you then look at the increase in landing distance for a Flap 3 landing then you will see it is only about 70 meters. So, unless you are approaching a runway where you are close to landing distance limits and there is turbulence/windshear Flap 3 is the way to go!

Surely 5 or 6 knots extra on Vapp (VLSconf3 opposed to Vref) won't have a significant effect on crab angle required.


Anyway here another FCOM reference
3.3.16 DESCENT PREPARATION

Check or modify the landing configuration. Always select the landing configuration on the PERF APP page : CONF FULL in the normal landing configuration. CONF 3 should be considered, depending on the available runway length and go-around performance, or if windshear/severe turbulence is considered possible during approach.

Thanks for the FCOM reference Phoenix!

I have heard this before, although the net effect would be to reduce the crab angle by about 1/10th of a degree?

Same kind of result with this. The change in effectiveness must be minute. Also, since the airbus is fly by wire, any input on the sidestick would surely give the same result regardless of speed. The surfaces may have to deflect a tiny bit more, but the computer will still give you what you ask for?

(Not discounting your thoughts Phoenix! Just giving my own view!!)

The less drag configuration is interesting. I also can see the benefit in a Flap 2 go-around although following windshear the configuration would not be changed intially, but a Flap3 windshear go-around would be better than Flap FULL.

Thanks for the thoughts guys! It's so easy to focus on the approach itself, when perhaps the benefit is only relevant for the go-around?

In my Big company, it's SOP on the A320/A321 to land Flap 3 (unless you can think of a reason not to) for the purpose of saving fuel, since the power settings are less.

Most of us are reasonably good at finding reasons not to..but they're not really a big deal, to be honest.

Good question-The old question comes up every time one opens the QRH at the overweight landing:Flaps-determine???(so much for the quick reference)
The answer is in FCOM 3.5.35..Missed approach climb gradients.
It's easier to fly the approach in config3 at the faster speed,and have a cleaner aircraft on the missed app climb after "go-around Flaps"(flaps selected to 2)..
The same thinking applies to OEI approaches,or high ambient temps.
The only time one Has to use Config Full is on a CAT2(visual slope)..
Didn't they cover any of this on your line indoc??
Cheers..:ok:

Absolutely, don't get me wrong, it is negligible. Also, you're right, the roll in normal law is a roll rate, so again there's no gain with the airbus for landing with CONF 3. I was just outlining the general arguments for landing with a lower flap setting in a crosswind, albeit thinking more in terms of a conventional aircraft.

I'm not an advocate for it. Like I said, I've used it myself a few times but didn't see any discernible difference over CONF Full.

I'm no 'bus driver, but since I think the question is fitting to all airplanes with choice of landing flaps, I will offer my view.

Lower flap setting gives you less drag, hence less engine power required, hence less noise. On our airplane in very heavy landing weights we MUST use flap 25 (instead of 30) in order to still be stage III.

Lower flap setting gives you a higher nose attitude. This is an advantage at very low weights, when the nose attitude is low to begin with, and the aircraft tends to 'float' during the flare. I find it makes a low-weight landing easier.

For the case of expected windshear, although this is not the SOP for us, reduced flaps will be superior, since you have better performance, and you are not allowed to change configuration during the recovery maneuver. Also added approach speed for gust compensation might sometimes at heavy weights put you close or above the max flap limit speed. Same is true for some hydraulic / flight control failures that require higher approach speed.

My philosophy is, unless you have a good reason (less crab on crosswind is not a good reason), use max flaps.

Happy Landings and Happy New Year

Correct, however should not be used of wet or worse runways.

Windshear, fuel, noise, missed approach gradients are positives, negative is the higher approach speed, greater landing distance, additional braking and wear, hydroplaning speeds, and possibility of a tail strike.

Judgment is needed, blanket policy for it does not make sense in all situations.

Windshear recovery on approach calls for no change of config until clear of the shear whilst climbing away with TOGA and following SRS pitch (ie max perf)
Doing this in Config 3 as opposed to config Full will give better climb perf.

I don't know the answer but I thought I'd throw this into the melting pot: Several folk have mentioned that using flap3 would lead to a higher pitch attitude, but surely the increase in approach speed would cancel that out(or to a degree anyway-no pun intended!)

C'Mon guys...let's not turn this into Rocket Science, what does your Ops Manual say?

What it says is what you do, how hard is that? :confused:

F3 in a 321 always tickles me. We get hammered with dangers of tail strikes and then they ask us to adopt a landing config tht increases the pitch att on finals by 1, maybe 1.5 degrees. Its not a lot but if you get a strong sink at 30R and yank back to arrest the rate you creep 1 maybe 1.5 degrees closer towards that 9 degree office meeting.
am I being a bit too cautious?

No Dozza, you're not being too cautious. Ideas like this are constantly being dreamt up by desk-driving gimps to save fuel or whatever, and improve bonuses for said management monkeys.

Once data about increased brake use (higher landing speeds) becomes available, or a tail-strike occurs for exactly the reason you suggest, then they will invent another policy to 'improve company performance'.

I'm surprised they don't ask for glide approaches! :ugh:

Well, look Dozza...
go see your Flight Manager, tell him you want his job, and if you get it, then rewrite the Ops Manual to suit yourself. But, and it's a big but, make sure you know what you're talking about.
you get my drift?

Come on amos2, it was a clear and relevant question from Dozza2k. My reply was probably more flippant ...... Yours? Well, you've shown your true colours - had a bad day at the office?

I know this topic is a bit old, but I just had to mention my company's policy. After fuel going up in the last few years they have sent a notice to flight crew asking us to try and land when ever possible CONF3 as it reduces fuel burn on the approach. We have never had a tail strike in the last 6 years operating 320/321. I can understand their philosophy, but I don't think we should over use CONF3 except for the odd time to keep current with power setting, pitch attitude and flare technique.
The only thing that has worried me in the last 2 weeks is that I heard from a line training captain that they might impose CONF3 to become the normal operation in the OPS manual, which I believe is not right. CONF3 and FULL should be a crews decision to make and not be made into a standard operating technique.

I hope you enjoyed my contribution.

Thrust is not one of our Airbus stable approach criteria!!

UK LoCo

Our company believes that use of Config 3 saves 20kg of fuel and it is the SOP landing configuration. It turns out that this fuel saving is only happens if you are fully configured for landing at 13 miles. Most of the final approaches on our route network don't come anywhere close to a 13 mile final (notwithstanding the rare and weird 30nm final:{). It seems to me an accountant's fudge; as any fule no, how the approach is flown from top of drop makes more difference than any flap configuration. :ugh:

As mcdhu says, thrust is not one of our stable criteria; it used to be, but the Autothrust seems to almost hunt for the correct power setting in Config 3, which is probably why the requirement for thrust was removed – it's just not necessarily there at 500'!

Applemacmaster:

We work for the same Company I belive and I can assure your information regarding fuel savings isn't correct. The actual fuel savings will vary due to weight and pilot technique. In fact there is actually no single figure for the A320 family. The values vary with the speed, which varies with each engine/aircraft/weight combination plus the engine characteristics (TI vs. non-TI) etc. You can be assured, however, that the average montly saving due to CONF 3 comes close to 10 times the TRIP fuel requirements from SSH to LGW - small numbers add up when you fly 1,100 flights/day.

On the Airbus there has never been a requirement to have a minimum thrust setting on the approach, the aircraft certification standards (FAR – Part 25) ensure that the thrust achieved after 8 seconds from power application (starting from flight/approach idle) allows a minimum climb gradient of 3.2 % for go-around.

The issue of tailstrikes on the A321 decreases when using CONF 3 instead of CONF FULL. This behavior can be explained when looking carefully at the lift surfaces. The A321 has doubleslotted fowler flaps, instead of single slotted flaps on the A319 and A320. Most tailstrikes occur due to aircraft mishandling.

Have a good summer.

landing withe confg 3
 

Ido agree using flap3 as you said for fuel price as long as a320 dosnot need long runway

Lyka,

Thanks for the detail; I'm happy to accept that I may have been misinformed (although my source was pretty good), but there is a dearth of (detailed) information on the subject. However, a lot of people still need a lot of convincing. I don't mind doing Config 3 landings, and quite like doing them for the team (200+ landings a year * "20kg" is a lot of fuel); in fact, I'm nerdy enough to log whether it's Config 3 or Full in my logbook. I still feel that there isn't enough focus on saving fuel in the rest of the sector; it's almost as if the emphasis is wholly on the landing Config, whereas a larger saving is to be made elsewhere. For example, I'm quite pro-active in trying to get shortcuts, but some guys will just stick with the flightplan.

Very interesting about the 321. I don't fly it, but a lot of guys who used to fly it would swear blind that it's a bad idea. Again, education is key.

Most heavy a/c i have flown are easier to land with full flaps as you will establish approach speed easier - close to MALW you need every drag you can get. Another point is the line of sight, but I guess all those who need not see the TDZ are well of with lower flap settings.
On the other hand, instead of dumping 20000 gallons, consider an overweight landing, and you will need lower flaps (3/25/30/etc.) and a long rwy. :O

I am glad that this topic has been resurrected. There is an ongoing debate by the line pilots at my carrier (at least out west here in PHX) about the purported saving in Config 3 landings. The company is saying that Config 3 is now the standard flap setting and full is to be only used when necessary for performance (wet, contaminated, Cat 3, etc.)

We have heard the same 20 kgs (50 lbs for us in the USA) savings mentioned but then someone brought up the point that all this is negated if you use greater than Idle reverse on landing.

In the Airbus (particularly the 321) you have far less stopping area on the disks (2 wheels per main gear) vs the larger Boeings. 737 and 319/320 are the same, of course. But pound for pound the Airbus empty weights are greater than the Boeing 737s. So you are using reverse thrust to compensate for the lesser stopping power of the Airbus brakes. The carbon brakes work best when heated but if you use Autobrake (recommended) then you have a 4 second delay before the brakes kick in. And you are coming in with cold brakes unless you are doing 45 minute sectors. Meanwhile the reversers are engaged and because we all want to stop before the end (always my main goal) we slide the revesers back to full. Look at the fuel flow - you will see about 1800 lbs/hr fuel flow per side while in reverse. Bring them to idle at 80 or 60 kts and you will have used your 50 lbs and maybe more. If you don't single engine taxi after your 3 minute cool down then you will burn 50 more. And don't forget, if you dropped the gear and went to final flaps at the FAF then you burned hundreds more pounds or kgs of fuel.

VFR I will drop the gear at 1500' agl and go to final flaps (3 or full) at 1000'. I will go managed speed at 5 miles out. I am spooled and stable between 1000' to 500' which is our VFR gate. Thats about as close to a constant idle descent as I can get and still be wiithin company parameters. Few F/Os I fly with will do that so I know that we are wasting far more fuel with early configurations and prolonged use of reverse than landing Config 3.

I assume we are talking A320 family here :rolleyes:

As above, my Big employer has an "SOP" for F3 on 320/321, FF on 319, in order to "save fuel". However, either Flap setting can be used on any model as crew see fit, and they also give a long list of factors that might affect that decision (e.g. EAI, tailwind, LDA).

My observations:[LIST=1][*]F3 saves about 7Kgs an approach - assuming the F3 to FF is selected just prior 1000' for "stabilised approach criteria" :E[*]A321 and A319 F3/FF Vapp is ~10K different, and attitude little changed[*]A320 only adds about 3K, and has much higher nose attitude, confirmed by "high nose attitude on Landing events" being a problem on, almost exclusively, F3 A320 approaches[*]On the A321 this can result in a comparatively high approach speed, which some circumstances might dictate best avoided[*]On the A319 the extra 10K can be very useful to get a decent approach speed / make an exit[*]My RHS colleagues do have a good line in excuses not to use F3 - which I can only assume reflects what most LHS do... :rolleyes:

Lots of good points made here and I just want to add perhaps another way of looking at it.....

If you take all these "fuel saving" measurements/procedures and add them up they will eventually, compared to not applying them, save the company some fuel. Agree on that? I think this is the way to look at it. Coming up with statements like "Yes, saves fuel but if you do not do x, y and z then bla bla or if you do this or that then....etc etc" is not really relevant to wether or not it makes sense to introduce the procedures. Remember, if you need to fly a fully configured approach, or just screw up you descend planning, the benefit of flying config 3 approaches is not lost. You have to compare used fuel on the particular approach compared to what would have been used if flying config full. Yes, more focus should be put on training pilots, and controllers, to fly A-CDAs (or similar) whenever possible. As for single engine taxi I often hear from people that yea but if you taxi uphill to the gate area then you have lost the benefit by using higher thrust setting on running engine". I am no tech geek and I am not sure if the statement is correct, but, if you think this is the case - Don't shut down the engine!! But shut down the engine in all the other 95% of you arrivals and you will, over time, save money.... How hard can it be?

I am all for config 3 landings, single engine taxi in, proper approach and descend planning etc. Saves fuel (money) and the environment.

mcdhu But Speed is - so if the path and speed are perfect but the thrust is at idle, the a/c must be decelerating, and the approach is not stable.......

CaptainProp: Some information for you. For a CFM 56-5B5 one engine at roughly 30% N1 produces a greater amount of thrust and burns LESS fuel than two engines at 19% N1. The arguement about upslopes needs to kept in context as it most probably forms only a small part of the total taxi time and the fuel flow, measured by the ECAM, isn't calibrated to that degree of accuracy.

My Company have published a breakeven distance (i.e., cost) to allow us to make an informed decision about additional taxi time vs. CONF 3 - it gives us a number to work from for RWY exit planning etc.

LYKA - Thanks for the info. My point was more along the line of use your brain when applying / not applying these procedures and stop trying to convince people that it makes no difference, because it does.

Hi,

Some interesting views expressed above.

There is an Airbus power point presentation called "Landing in CONF 3 – Use of reversers"

My company is planning to introduce flap 3 landings on the A320/321 as SOP :(

So I searched PPRUNE and found this "old" but interesting tread about the subject.

The reason for the new SOP is : 1. FUEL SAVING and 2. noise


My question is :

Have you seen any documentation about saving money if using flap 3 instead of flap full for landing ?

I mean, I can understand that you are saving a very limited amount of fuel if you are using flap 3 instead of flap full, but we are talking about ~2 min. on each approach, and in my company the aircrafts are doing between 2 and 4 landings pr day so we are not talking about a lot of fuel.
And if you have do make ONE GA due to lack of spool up (which is more likely to happen in flap 3 than flap full) then I guess that what have been saved in a whole year, just disappeared !
And what about the increase the brake wear ? What are the costs here ?
And off course the increase risk of a tailstrike on the 321....

Please share your experience/thoughts

A few notes:

1- What difference does it make setting landing conf 3 instead of full just at the limit altitude (500 or 1000 ft depending non VMC or IMC)? I think it is negligible with respect to any flighttime not at idle during the approach due to a non optimum TOD and descent. Not to mention the much greater saving of a "more thant optimum descent" such as going low on profile, then "ready for base" and fly some 6 to 10 less NM.

2- does the fuel saving outweights the extra fuel, engine wear and brakes wear due to the extra speed? (in the ecuation of kinetic energy, speed goes squared: a 3% extra speed means a 6% extra energy).

3- I rarely fly conf 3, and i don't like it because i am not used and with light weights thrust is almost idle. And i feel a tailstrike is more likely to occur to me, which is scary.

4- Maybe it is better just to delay flap full until shortly before 1,000 ft, instead of the procedural, when flaps 3, select flaps full

5- a lot of bits of fuel saved can make a big saving in a big airline

6- just one incident (tailstrike) can waste years of saving

7- i would like captains to encourage me to fly conf 3 approaches, but they don`t like it. So i dont like it when a conf 3 is recommended for windshear and gusty winds, because aside from the conditions I have to deal with an unusual attitude and thrust.

8- Extra time taxiing is also a factor, which will occur in many airfields if you use more rwy length. For instance at FCO after landing you may just let it roll with reverse idle to the end. conf 3 that day is fine. But in other airports, the extra speed will be paid either by extra reverse and braking or extra taxi time. Time is more expensive than just fuel.

9- To what extent are experts the experts who say that conf 3 landings save money?

.......and don't forget to have a look at QRH 4.04 for a realistic landing distance required.

I'm slightly puzzled by the fact that none of the responses mentions the reason for having a choice of landing flap settings in the first place. Is it off-topic or is it because the FCOM doesn't mention the Performance Limitations listed in the Airplane Flight Manual?