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Why Not Fully Extend Flaps When Landing?  
User currently offlineTheflcowboy From United States of America, joined Jan 2004, 405 posts, RR: 0
Posted (7 years 9 months 3 weeks 6 days 22 hours ago) and read 8432 times:


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Why would a plane land not using full flaps?


A318, A320, A332, A333, B1900, B722, B732, B733, B734, B735, B737, B738, B772, CR1, CR2, CR7, CR9, MD80, MD81, MD82, MD8
54 replies: All unread, showing first 25:
 
User currently offlineN231YE From , joined Dec 1969, posts, RR:
Reply 1, posted (7 years 9 months 3 weeks 6 days 22 hours ago) and read 8427 times:

Noise control is one of the reasons...

User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 2, posted (7 years 9 months 3 weeks 6 days 22 hours ago) and read 8418 times:

I know on the B738 and B739 CO uses flaps 30 most of the time to lessen the tail strike possibilities.


Any views shared are strictly my own and do not a represent those of any former employer.
User currently offline3DPlanes From United States of America, joined Apr 2006, 167 posts, RR: 0
Reply 3, posted (7 years 9 months 3 weeks 6 days 22 hours ago) and read 8417 times:

More flaps equal more drag, which for a stabilized approach means more thrust required... Providing another source of noise, and of course using more fuel.

Coming from a GA perspective, I would think that for the bigger planes, the runway length and/or landing weight would be the major factors for determining how much flap to use.

In some GA planes, its routine to not use full flaps - unless you need the short field performance. Others use full flaps on most every approach, unless you want to minimize the effect of gusts and/or a crosswind.



"Simplicate and add lightness." - Ed Heinemann
User currently offlineTheflcowboy From United States of America, joined Jan 2004, 405 posts, RR: 0
Reply 4, posted (7 years 9 months 3 weeks 6 days 21 hours ago) and read 8392 times:

Quoting IAHFLYR (Reply 2):

Can you explain this more? How does this reduce tail strike possibilities?



A318, A320, A332, A333, B1900, B722, B732, B733, B734, B735, B737, B738, B772, CR1, CR2, CR7, CR9, MD80, MD81, MD82, MD8
User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 5, posted (7 years 9 months 3 weeks 6 days 21 hours ago) and read 8395 times:

Well, for one, if I turn final and I'm below the VASI, I'm not going to add full flaps, because I'll also be adding tons of power to maintain altitude until I'm back to red over white...


Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offline2H4 From United States of America, joined Oct 2004, 8956 posts, RR: 60
Reply 6, posted (7 years 9 months 3 weeks 6 days 21 hours ago) and read 8384 times:
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Quoting Theflcowboy (Reply 4):
Can you explain this more? How does this reduce tail strike possibilities?

Extending the flaps increases the angle of attack. This reduces the deck angle required to maintain a given angle of attack. Shallower deck angle in the flare = less chance of a tailstrike.  Smile


2H4





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User currently offlineDKCFII From United States of America, joined Feb 2007, 22 posts, RR: 0
Reply 7, posted (7 years 9 months 3 weeks 6 days 20 hours ago) and read 8355 times:

This may apply more to smaller aircraft, but when there's really strong crosswinds or gusty conditions I use less flaps. It helps in maintaining directional control of the airplane, and allows for more versatility in terms of changing your flight config should things go awry.

User currently offlineRendezvous From New Zealand, joined May 2001, 521 posts, RR: 0
Reply 8, posted (7 years 9 months 3 weeks 6 days 19 hours ago) and read 8335 times:

using flaps may reduce the deck angle for the same airspeed, but generally the use of them is to reduce the approach speed, which means it would be a similar deck angle whether flaps 30 or 40 were used.

User currently offlineThirtyEcho From United States of America, joined Dec 2001, 1659 posts, RR: 1
Reply 9, posted (7 years 9 months 3 weeks 6 days 16 hours ago) and read 8296 times:

Control surface authority increases with airspeed; the rudder, ailerons and elevators have more "power" at higher airspeeds. If you are landing in a gusty, crosswind environment, this is what you want, You don't want to be loitering at low speed over the runway while being blown this way and that way with low control surface authority. A lower flap setting will give you a higher touchdown speed.

When I began flying, many decades ago, flaps were regarded as a "crutch" used by bad pilots. If you needed to kill altitude and airspeed during an approach, you did a sideslip.


User currently offlineFrancoBlanco From , joined Dec 1969, posts, RR:
Reply 10, posted (7 years 9 months 3 weeks 6 days 13 hours ago) and read 8242 times:

While most larger aircraft fully extend the flaps for landing (except for crosswind landings, engine-out landings, etc.), the 737 usually uses flaps 30. Flaps 40 is only used for short fields, high landing weight, etc. Flaps 40 is also more common on 738 and 739 models, on the other hand, as already mentioned, it increases the possibilty of tail strikes.

From my understanding, the original 737 inherited the wing from the 727 (which also had a flaps 40 position). Since the 737 is a lot shorter and lighter than the 727 (at least the classic models), flaps 40 are not needed most of the time.

Sebastian


User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 11, posted (7 years 9 months 3 weeks 6 days 12 hours ago) and read 8223 times:

Quoting FrancoBlanco (Reply 10):
While most larger aircraft fully extend the flaps for landing

On the 744/747 flaps 25 and 30 are considered landing flaps. It is just a matter of company SOP.


User currently offlineVikkyvik From United States of America, joined Jul 2003, 10332 posts, RR: 26
Reply 12, posted (7 years 9 months 3 weeks 6 days 10 hours ago) and read 8168 times:

Quoting 2H4 (Reply 6):
Extending the flaps increases the angle of attack. This reduces the deck angle required to maintain a given angle of attack. Shallower deck angle in the flare = less chance of a tailstrike.

So what you just told me is that more flaps = shallower deck angle. That's correct, but it doesn't exactly explain:

Quoting IAHFLYR (Reply 2):
I know on the B738 and B739 CO uses flaps 30 most of the time to lessen the tail strike possibilities.

unless there's something I'm missing  Smile

Maybe it just takes a lot of flare to arrest the descent on a flaps-40 landing?

Quoting FrancoBlanco (Reply 10):
While most larger aircraft fully extend the flaps for landing (except for crosswind landings, engine-out landings, etc.),

I'm not entirely sure that's accurate. As Phil said, the 744 has two landing flap settings. I believe that many Airbus aircraft can use the either of the highest two flap configs for landings. This is just what I remember reading, though.

~Vik



How can I be an admiral without my cap??!
User currently offlineEridanMan From United States of America, joined Dec 2005, 121 posts, RR: 1
Reply 13, posted (7 years 9 months 3 weeks 6 days 7 hours ago) and read 8060 times:

Yeah, I'm kinda confused about the tailstrike thing too, unless the argument is more flaps = less chance of tailstrike (in which case it hasn't been stated well).

Anyone whose landed a clean plane knows that you really have to get the nose WAY up in the flare.


User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 14, posted (7 years 9 months 3 weeks 6 days 5 hours ago) and read 8007 times:

Quoting Vikkyvik (Reply 12):
unless there's something I'm missing

I have simply been told this by some of their crews so certainly no first hand knowledge and yes my initial thought was a lower deck angle as well.....I know they (CO) uses flaps 30 on those alot with ref speeds in the 155 KIAS range, they catch the preceeding arrival pretty quick on final.

Quoting Vikkyvik (Reply 12):
Maybe it just takes a lot of flare to arrest the descent on a flaps-40 landing

And lots of power as well....chop the power I'm told on the 800/900 with flaps 40.....better hang on as it is coming to the runway in a hurry.

Again, only passing on what I'm told from guys who drive them around....so I offer that caveat!  Smile



Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 15, posted (7 years 9 months 3 weeks 6 days 3 hours ago) and read 7943 times:

If you need to get a steep climb gradient in the event of going missed, you want to land fast if the runway length will permit it. Higher speed on the approach means more energy to convert into altitude quickly. Not to mention that in many aircraft the climb performance will not be optimum to begin with with full flaps.

Rgds,
/Fred



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 16, posted (7 years 9 months 3 weeks 6 days 1 hour ago) and read 7894 times:

On the MD-11 the use of flaps 50 will decrease stop dist by only about 500' ft. but adds more stress on the airframe. Flaps 35 is normal with 50 being used mostly for CATIII.

User currently offlineDigbyDude From Spain, joined Feb 2007, 28 posts, RR: 0
Reply 17, posted (7 years 9 months 3 weeks 5 days 2 hours ago) and read 7761 times:

Not a pro as one can probably tell, but I recall when coming into land on a 752, when the flaps were set the front of the plane felt to be pointing downwards quite a lot, is this just a feeling, or on a 752 does the plane actually point nose down during approach ?

Adam


User currently offlineMDorBust From , joined Dec 1969, posts, RR:
Reply 18, posted (7 years 9 months 3 weeks 5 days 1 hour ago) and read 7733 times:

Quoting DigbyDude (Reply 17):
...or on a 752 does the plane actually point nose down during approach ?

What phase of the approach?

Every plane that I can think of has it's nose down at some point in the approach. Only late in the approach do planes start flying in a nose up attitude.


User currently offlineHighFlyer9790 From United States of America, joined Jul 2005, 1241 posts, RR: 0
Reply 19, posted (7 years 9 months 3 weeks 5 days 1 hour ago) and read 7727 times:

Quoting MDorBust (Reply 18):
Every plane that I can think of has it's nose down at some point in the approach. Only late in the approach do planes start flying in a nose up attitude.

the heavier the aircraft and the slower the aircraft the earlier it will pitch nose up. generally, most commercial aircraft start to go noticably nose up during the flare, starting around 200 feet. in GA aircraft, it really only starts in the flare, around 20 feet!  Smile

generally, i wont go full flaps with gusty conditions (C172) because it makes the plane easier to handle, flying the approach about 10 kts faster until the threshold.



121
User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 20, posted (7 years 9 months 3 weeks 4 days 23 hours ago) and read 7702 times:

Quoting MDorBust (Reply 18):
Every plane that I can think of has it's nose down at some point in the approach. Only late in the approach do planes start flying in a nose up attitude.

I used to drive home down Interstate 205, right by the approach end of RWY 28L and 28R at PDX. By the time they crossed I-205, they were already in a nose high attitude. It looks strange...I'd say the one that most amazed me (due to the apparent high alpha) was FX's MD-11's...not sure if that's due to FX's flight procedures or the nature of the MD-11  Wink



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineHighFlyer9790 From United States of America, joined Jul 2005, 1241 posts, RR: 0
Reply 21, posted (7 years 9 months 3 weeks 4 days 23 hours ago) and read 7699 times:

Quoting KELPkid (Reply 20):
not sure if that's due to FX's flight procedures or the nature of the MD-11

nature of the MD-11, i think  wink 



121
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 22, posted (7 years 9 months 3 weeks 4 days 13 hours ago) and read 7598 times:

Quoting KELPkid (Reply 20):
I'd say the one that most amazed me (due to the apparent high alpha) was FX's MD-11's...not sure if that's due to FX's flight procedures or the nature of the MD-11

There are no procedures here that dictates an app. pitch that's particular to FEDEX. The MD-11 has about a 3 deg. nose up att from glide slope intercept down. The flair takes you to about 6 or 7. At 11 or more you''ll hit the tail. We fly the jet by the manuf. specs. With flaps 50 it will be lower att. but NEVER a negative att.Personally I''ve never flown a jet that DID have a nose low app attitude. I know some w/o slats (short DC-9) may but it isn''t the norm.


User currently offlineUsair320 From United States of America, joined Nov 2003, 991 posts, RR: 2
Reply 23, posted (7 years 9 months 3 weeks 4 days 1 hour ago) and read 7467 times:

Well in the Cessna 150 that I fly it is because 40 degrees of flap is to much drag for the 8,000 ft runway I land on. $0 degrees can cause a hell of a lot of drag resulting in one hell of a stall.

User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 24, posted (7 years 9 months 3 weeks 4 days 1 hour ago) and read 7457 times:

Quoting Usair320 (Reply 23):
Well in the Cessna 150 that I fly

If you notice I said jet. I too have a whole bunch of time in small Cessnas and understand what you're saying.

Quoting Usair320 (Reply 23):
40 degrees of flap is to much drag for the 8,000 ft runway I land on.

What's the runway have to do with it?


25 Post contains images KELPkid : The Cessnas that don't have flaps restricted to 30 deg. can make some amazing drop-in approaches right on the numbers at short mountain strips  Howe
26 2H4 : It's been awhile since I've flown a 150, but I don't recall a lower flap setting resulting in more violent stall characteristics... 2H4
27 Post contains images IAHFLYR : Heck 40 degrees of flaps on a C150 would be way too much drag on a 2,500' runway!!!
28 Post contains images KELPkid : I recall my 1st flight instructor teaching me to do an approach configuration stall in a 150 whose flaps went to 40 degrees...on recovery, he taught
29 Post contains images 2H4 : Indeed. I love it when the scenery seems to come up more quickly than it seems to go past... When landing, I am of the opinion that...so long as forw
30 ThirtyEcho : Gotta love those 40 degree flaps on the early Cessnas. I've dropped into many a 2000 foot long and 35 foot wide runway, over the tops of 50' pine tree
31 BAe146QT : If your CFI used to be a Naval aviator; "Man, that was a short runway." "Yeah but look how *wide* it is!"
32 Pygmalion : For most aircraft, the change in wing shape as a result of adding flaps does two things, It increases lift and adds drag. For any given angle of attac
33 Post contains images KELPkid : Well, in most Cessna high wing models a short and/or short and soft field takeoff calls for 10 deg. flaps...milked up once your airborne in ground ef
34 JetMech : I think that one of the reasons full ( 30 degrees ) flaps is sometimes not used by particular operators of B744's is due to brake wear considerations
35 PhilSquares : Actually, QF was a 30 flap landing company, min reverse and autobrakes 3. The increase in Vref is from 5-7 knots depending on your weight. The additi
36 Post contains links and images JetMech : G'day Phil , Yes, apparently QF was a flaps 30 company as stated in their B744 procedures manual. Apparently, maximum reverse thrust was also SOP alth
37 PhilSquares : G'day JetMech, Not to hijack this to a QF analysis.....but If you check (p52) you'll find Boeing's recommendation about 25 v. 30 flap landings. Boeing
38 Post contains images JetMech : G'day Phil , Thanks so much for the input! It is always fascinating and most informative to get the pilots perspective on such issues !. The language
39 PhilSquares : I really prefer flaps 25, moderate reverse and autobrakes 2. Once I'm down to 100 knots or so, I tap the brakes to deactivate the autobrakes and then
40 OldAeroGuy : If you extend flaps at constant airspeed, CL will increase so angle of attack needs to decrease to maintain level flight. Generally speaking, increas
41 411A : Not using the maximum flap setting for landing, began a long time ago, with Pan American, with B707 aircraft, circa 1960, after a couple of years oper
42 Vikkyvik : Is that because you'd be at a higher power setting for a flaps 50 landing? There's a few things involved that I can see, in terms of which is better
43 OldAeroGuy : For the JT3D series, very much so.
44 Post contains images Vikkyvik : Gotcha Thanks. ~Vik
45 Wing : Flaps 30 is the normal landing flap setting for 737-400 series.(Period)
46 JetMech : Thanks again Phil! It seems as though you are allowed to exercise much discretion and judgement in the landing configuration you choose to utilise. I
47 ThirtyEcho : "Man, that was a short runway." "Yeah but look how *wide* it is!" Good for you; you got the joke. There was a Cub pilot at my local airport who would,
48 2H4 : Thanks, OAG. I think I was making an incorrect correlation between chord line and AOA. 2H4
49 Pilotaydin : sometimes it is good to use flaps 30 on the 737 because incase of a go around, the climb performance is much greater, and at places like Pristina or S
50 Molykote : I haven't had the opportunity to read this yet but what a well produced report!
51 CosmicCruiser : I've never flown a 737 so I'm curious when you say this. Do you keep ldg flaps throughout the g/a? For us in the 11, flaps 28 is the next thing after
52 FredT :
53 Scramjetter : ILS approaches tend to be long and fairly flat. Higher flap settings are used when there is a need to steepen an approach by adding more drag. So to m
54 CF188A : control issues at lower speeds in different weather conditions
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