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futureatp
Topic Author
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737 Flap Settings And Company Policy

Wed Dec 20, 2006 4:09 am

It appears to me that when I fly in and out PHX that Southwest and America West use different flap settings on takeoff for the B737-300. I have noticed this as a passenger awaiting takeoff out of PHX during a busy period. I am not just comparing two aircraft. Everytime I go in and out of PHX and look at the aircraft I notice this so I throw out the Idea that it could be aircraft loading. It looks like Southwest uses more Flaps on the -300 than does America West for takeoff.

I then have assumed that there is a difference in company policy between these two carriers.

The questions I have are:

Is there really a difference or are my eyes being tricked?

If they do use different flap settings, what exactly is the advantages/disadvantages? My basic understanding is climb out performance vs. A shorter takeoff run.(am I right?)

And for possible company insiders-What is the operational philosophy?

I have my single engine commercial, and I have some basic knowledge of aircraft aerodynamics.

Thanks in advance. Im pressed for time. If any more details is needed that I could possibly give, let me know.

John
 
N243NW
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RE: 737 Flap Settings And Company Policy

Wed Dec 20, 2006 4:38 am

Hi Futureatp,

I can't give any real help regarding takeoff flap settings, but I know a lot of 737 operators have locked out the Flaps 40 setting and use Flaps 30 for landing instead. This cuts down on noise significantly and does not have too much of an effect on the landing roll. I never use Flaps 40 when I land the 737 Classic in the simulator and it doesn't result in much of an increase in touchdown speed.

I know that on many large aircraft such as the 737, the FMS does most of the work calculating power settings and flap settings for takeoff. Due to many factors such as runway length, weather, aircraft weight, and noise restrictions, different flap settings are used. I'd have to turn it over to one of the professionals on the board at this point, though.

-N243NW Big grin
B-52s don't take off. They scare the ground away.
 
amtrosie
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RE: 737 Flap Settings And Company Policy

Wed Dec 20, 2006 4:59 am

As for take-off, aircraft loading, current temperature, altitude, fuel loaded, packs on/off etc. will dictate your flap settings at take-off. The powerplant will also influence settings. As for landing, that is fairly standard and should not vary between operators.
 
Curmudgeon
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RE: 737 Flap Settings And Company Policy

Wed Dec 20, 2006 8:06 pm

The 737-300 (and -200, for that matter) can use flaps "one" for take-off. (The -400 cannot due to tailstrike concerns).

Flaps one requires a longer runway, but yields better climb performance. If runway length is not a factor, flaps one also yields a slightly reduced trip fuel. (I can't cite exact figures, but I seem to recall an issue of Boeing Airliner that claimed a 45 kg/100 lb difference in fuel). Having flaps one charts and approval is an extra cost item, and airlines will only pop for the extra cost if it fixes a definite problem for them. Were the HP flights you observed on longer flights, hence heavier?

Landing flap often boils down to personal pref, with most guys liking 30 more than 40. On the -800 series 40 is preferable because the -800 is heavier and a bit more of a runway hog. The difference in approach speeds is 5 kts on the 300/400 and 8 kts on the NG.

Cheers...and well spotted.  Smile
Jets are for kids
 
IAHFLYR
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RE: 737 Flap Settings And Company Policy

Wed Dec 20, 2006 9:52 pm

Quoting Curmudgeon (Reply 3):
On the -800 series 40 is preferable because the -800 is heavier and a bit more of a runway hog.

Interesting, as a check airman friend of mine that does IOE and line checks in 800's & 900's, tells me their company prefers and teaches flaps 30 for landing due to less chance of a tail strike and smoother landings, sure the ref speed is up around 155-160 KIAS but that isn't an issue unless a very short runway. The flaps 40 landings do require alot more power which burns gas and makes more noise as mentioned, then there is the movement of the throttles to idle and if you didn't bring your "A game" it isn't gonna be pretty..........BANG  bouncy 
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vikkyvik
Posts: 12621
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RE: 737 Flap Settings And Company Policy

Wed Dec 20, 2006 10:44 pm

Quoting Curmudgeon (Reply 3):
The 737-300 (and -200, for that matter) can use flaps "one" for take-off. (The -400 cannot due to tailstrike concerns).

On the 737, does Flaps 1 just extend the leading edge devices? Or do the trailing edge flaps also extend a bit?

Thanks.

~Vik
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
BAE146QT
Posts: 981
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RE: 737 Flap Settings And Company Policy

Wed Dec 20, 2006 11:38 pm

Quote:
On the 737, does Flaps 1 just extend the leading edge devices?

I can't find a definitive answer for this, but a quote I found says that the LE devices come out whenever the TE devices are extended.

Since the LE devices extend at "flaps 1", I infer from this that "flaps 1" really does mean that there is one degree of flap extended.
Todos mis dominós son totalmente pegajosos
 
OPNLguy
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RE: 737 Flap Settings And Company Policy

Thu Dec 21, 2006 12:08 am

Quoting Vikkyvik (Reply 5):
On the 737, does Flaps 1 just extend the leading edge devices? Or do the trailing edge flaps also extend a bit?

First, keep in mind that on the 737, there are two kinds of leading edge devices: leading edge Krueger flaps (between fuselage and engine), and leading edge slats (outboard of the engines).

When the trailing edge flaps are selected to positions 1, 2, or 5, the leading edge flaps and leading edge slats extend to an intermediate position. When the trailing edge flaps are selected to positions 10 through 40, the leading edge flaps and leading edge slats go to the fully extended position.

Quoting BAe146QT (Reply 6):
Since the LE devices extend at "flaps 1", I infer from this that "flaps 1" really does mean that there is one degree of flap extended.

While they extend at flaps position 1, they are not yet fully extended as per the above.

Note that Boeing uses flap "positions", and they do not corrolate to degrees as do the McD aircraft, and perhaps some others...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
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ThrottleHold
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RE: 737 Flap Settings And Company Policy

Thu Dec 21, 2006 12:20 am

Quoting N243NW (Reply 1):
I know a lot of 737 operators have locked out the Flaps 40 setting and use Flaps 30 for landing instead.

Boeing recommend Flap 40 for CAT II/II approaches. The reduced deck angle gives extra forward vision when breaking out at minimums.
 
OPNLguy
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Joined: Tue Jun 15, 1999 11:29 am

RE: 737 Flap Settings And Company Policy

Thu Dec 21, 2006 12:26 am

Quoting N243NW (Reply 1):
but I know a lot of 737 operators have locked out the Flaps 40 setting and use Flaps 30 for landing instead. This cuts down on noise significantly and does not have too much of an effect on the landing roll.

I know they used to do this with the 727s, but I've never heard of the this lock-out being done on 737s. In addition to the CAT-II/III consideration ThrottleHold mentioned, there are places (BUR and MDW come readily to mind) where flaps-40 is usually the norm....
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
vikkyvik
Posts: 12621
Joined: Thu Jul 31, 2003 1:58 pm

RE: 737 Flap Settings And Company Policy

Thu Dec 21, 2006 12:47 am

Quoting OPNLguy (Reply 7):
First, keep in mind that on the 737, there are two kinds of leading edge devices: leading edge Krueger flaps (between fuselage and engine), and leading edge slats (outboard of the engines).

I thought so, which is why I said "leading edge devices" and not "leading edge flaps" or "leading edge slats."  Smile

So sounds like both LE and TE extend incrementally up to Flaps 10, at which point the LE are at max extension, and past which, only TE extend further.

Thanks for the answers.

~Vik
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
FrancoBlanco
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RE: 737 Flap Settings And Company Policy

Thu Dec 21, 2006 1:55 am

Just for what it's worth, at INN all 737-700s as well as -800s use Flaps 40 for landing. Of course that's on a 2000m (6500ft) runway.

Sebastian
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BAE146QT
Posts: 981
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RE: 737 Flap Settings And Company Policy

Thu Dec 21, 2006 6:48 am

Thank you for the clarification, OPNL. I had no idea that the position did not relate to actual degrees. Is that just a hangover from the times when they would have, do you think? Perhaps to keep to some sort of unofficial industry standard and avoid confusing pilots?

Quoting OPNLguy (Reply 7):
When the trailing edge flaps are selected to positions 1, 2, or 5, the leading edge flaps and leading edge slats extend to an intermediate position. When the trailing edge flaps are selected to positions 10 through 40, the leading edge flaps and leading edge slats go to the fully extended position.

The reference I have only describes that behaviour on the Classic and ADV, and doesn't go into detail about the NG.

As my life doesn't depend on it right now, I'll go right ahead and assume that the NG is the same, since that would be a fairly major aerodynamic change that I can't really think of any reason for!
Todos mis dominós son totalmente pegajosos
 
futureatp
Topic Author
Posts: 195
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RE: 737 Flap Settings And Company Policy

Thu Dec 21, 2006 7:31 am

Thanks a lot so far guys. As far as when I notice these things, it is out of PHX and both WN and HP do a lot of short hops and longer hops out of PHX with -300s. I have no idea what the load would be or at the time where each aircraft is going. But they always seem to have their flaps set in way I described, kind of why I thought it was company specific. Also notice I reference HP and NOT US as they are still on separate operating certificates and I have no idea how much, if any, operating procedures have been standardized between the two carriers.

Would I be correct in assuming that HP is using Flaps 2 and WN using Flaps5?

I have been an airplane nut ever since my first aircraft ride when I was real young. And while I have given up on a Pilot career in favor of more boring stuff, my interest is still great.(im too lazy to change my username!)

Anyway, I frequent this site a lot. Ill probably be back with more!
 
OPNLguy
Posts: 11191
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RE: 737 Flap Settings And Company Policy

Thu Dec 21, 2006 8:42 am

Quoting BAe146QT (Reply 12):
Thank you for the clarification, OPNL. I had no idea that the position did not relate to actual degrees. Is that just a hangover from the times when they would have, do you think? Perhaps to keep to some sort of unofficial industry standard and avoid confusing pilots?

Somewhere, sometime, I once read about what Boeing's rationale was for doing it this way, but dang if I can remember what it was. Maybe it was to convey some sense of "proportional" relationship between the position settings versus just having them identified using degrees. I never dispatched a 707 in my career, but if Boeng used the same scheme on them, it'd probably a carryover into everything else they made.

Quoting BAe146QT (Reply 12):
As my life doesn't depend on it right now, I'll go right ahead and assume that the NG is the same, since that would be a fairly major aerodynamic change that I can't really think of any reason for!

The NGs are the same way, with the diiferences being that they have an additional L/E slat on each wing, and the T/E flaps are 2-piece versus the 3-piece assembly that are on the -100s through -500s.

If you're looking for good 737 info, try: http://www.b737.org.uk/

Quoting Futureatp (Reply 13):
Would I be correct in assuming that HP is using Flaps 2 and WN using Flaps5?

Flaps-2 is only a takeoff setting for the -200s (and I assume the -100s), and I'm sure HP has long since gotten rid of theirs.

The -300s use flaps 1, 5, or 15.
The -500s use flaps 5 or 15.
The -700s use flaps 1, 5, 10, 15, or 25.

The above takeoff settings are all AFM (Airplane Flight Manual) limitations.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
NineSixteen
Posts: 4
Joined: Mon Dec 18, 2006 5:41 am

RE: 737 Flap Settings And Company Policy

Fri Dec 22, 2006 10:03 pm

Quoting OPNLguy (Reply 7):
When the trailing edge flaps are selected to positions 1, 2, or 5, the leading edge flaps and leading edge slats extend to an intermediate position. When the trailing edge flaps are selected to positions 10 through 40, the leading edge flaps and leading edge slats go to the fully extended position.

not quite ... the Leading Edge Flaps, (aka Kreuger Flaps) are two (2) position devices, having only retracted and extended possibilities. They are extended for all TE Flap settings 1 - 40.

The Leading Edge Slats are three (3) position devices, having retracted, mid-extend, and full-extend positions. The Slats programming is how you described.
 
OPNLguy
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RE: 737 Flap Settings And Company Policy

Fri Dec 22, 2006 10:45 pm

Quoting NineSixteen (Reply 15):
not quite ... the Leading Edge Flaps, (aka Kreuger Flaps) are two (2) position devices, having only retracted and extended possibilities. They are extended for all TE Flap settings 1 - 40.

The Leading Edge Slats are three (3) position devices, having retracted, mid-extend, and full-extend positions. The Slats programming is how you described.

You're correct. After taking care to delineate the difference between L/E flaps and L/E slats, I managed to confuse two, but in their operation.

Have a Merry Christmas...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

RE: 737 Flap Settings And Company Policy

Thu Dec 28, 2006 2:47 pm

Quoting N243NW (Reply 1):
can't give any real help regarding takeoff flap settings, but I know a lot of 737 operators have locked out the Flaps 40 setting and use Flaps 30 for landing instead. This cuts down on noise significantly and does not have too much of an effect on the landing roll. I never use Flaps 40

Flaps 40 was locked out on 737-200s and most 727s due to Stage 3 compliance. Most operators in the US (if not all) have flaps 40 available.

Most 737 -5/4/3/7/8/9 takeoffs are flaps 5; flaps 1 is used on some models if runway length permits, which allows higher MGTOWs.
 
N243NW
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RE: 737 Flap Settings And Company Policy

Thu Dec 28, 2006 3:08 pm

Quoting EssentialPowr (Reply 17):
Flaps 40 was locked out on 737-200s and most 727s due to Stage 3 compliance. Most operators in the US (if not all) have flaps 40 available.

Thanks for the clarification.

-N243NW Big grin
B-52s don't take off. They scare the ground away.
 
pilotaydin
Posts: 2100
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RE: 737 Flap Settings And Company Policy

Thu Dec 28, 2006 5:52 pm

hey future, just inputting some more info, i fly the 737 and she's amazing. Flaps 5 takeoff is pretty standard, but sometimes we do flaps 15 on hot days or on days where we have limited runway, like Strasbourg in France. The -400s performace for summer time in turkey is very tricky with loading, density altitudes are an issue and also assumed temp takeoffs are impossoble.

For landing, flaps 40 is very stable and requires very little flare, flaps 30 is what boeing recommends for normal landings and also overweight landings. A good trick for you guys out there if you can somehow figure out your gross weight, ask the crew without freaking them out...let's say your GW comes out to around 55,000 kgs, just subtract 5 from that number (55-5) and that will give you the V2  Smile on the NG aircraft subtract 20 (75-20) so V2 would be around 155

it works wonders and it's a great way to check if we're gonna get airborne or run out of runway lol and from those just subtract about another 10-12 and u get your V1 and Vr speeds, we're done  Smile

any other questions lemme know
The only time there is too much fuel onboard, is when you're on fire!
 
NineSixteen
Posts: 4
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RE: 737 Flap Settings And Company Policy

Wed Jan 03, 2007 2:09 pm

The TE flaps of the 737 Classic was a selling feature. Both inboard and outboard Flaps were made up of a 3 segments (fore, main, and aft). The drive system positioned the main flap, and the fore and aft flaps were articulated off the main. A plethora of settings, (0,1,2,5,10,15,25,30,40) gave the airplane competitive takeoff/landing performance characteristics way back when. But they were a maintenance headache, requiring frequent servicing, and the oiled jackscrews were problematic. The 737NG TE flaps are more simple, consisting of only two segments, and the components are way more reliable.

Two segmented 737 NG TE flap
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71Zulu
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RE: 737 Flap Settings And Company Policy

Wed Jan 03, 2007 3:42 pm

Flew MSY-MIA recently on an AA 738 and upon landing at MIA the pilot flying really banged it on. I was almost the last one off and joked with the Captain standing at the door and he admitted he was flying and it was a flap 40 landing, and was mad at himself for doing it and blowing the landing. He said that the flap 30 in his opinion was much easier to fly and made for smoother landings and that is the setting he normally uses.

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