full flaps for every landing?

[jdog78]

I've been participating in a discussion on airliners.net about a guy on a Singapore 777 wondering what the unusual vibrations are that he experienced on finals to Kuala Lumpur that could not be attributed to the spoilers, which were stowed. I suggested that it was caused by the flaps vibrating because they were at or near full flap setting and it was unusual to him because full flaps are not used on every landing.
As we know, the last notches of flaps usually create more drag than lift so buffeting of the flap can occur at those higher flap settings on planes from the 172 to the 777, caused by turbulent airflow on the back side of the flap.
Even in the 172 i wouldn't use full flaps unless i'm practicing short field landings or fast on the approach. So that explanation seemed to fly with them.
Some asian pilots in the forum stated that their operating procedures actually require a full flaps landing every time. Is this also the case in the US? I almost never experience vibrations when i'm riding in a jet unless they put out all the flaps. I'm also under the impression that US airlines prefer the pilots not use full flaps to save fuel and also to reduce environmental noise. Any input would be much appreciated.

john

 

[avbug]

Unless an operational requirement exists not to use full flaps, I use them on each landing. In each case, operate the aircraft in accordance with the manufacturer direction, taking consideration for company guidelines or policy.

 

[TwinTails]

AvBug has answered your question. No frills, just do what the POH or the Ops. specify.

I use full flaps on every landing in anything I fly from Pa-18 to King Air. Why not? I guess some of what was instilled in me when first learning has stuck. Runway behind you is as useless as the altitude above. I seriously have to conciously think about it when Im on a check ride to fly the VASI all the way to the pavement. I always wanna touch the numbers.

 

[bigsky]

I usually have preferred the handling characteristics of an airplane at less than full flaps-- However, especially in a large transport category airplane making a greaser every time is not always the most important thing. Stopping a plane that weighs over 400,000 lbs on a given amont of runway is the priority. Full flaps are not always required but will allow for slower approach speeds and more drag on rollout. ( In a 172 one technique was to put the flaps up after touchdown to get the weight of the airplane on the wheels and better braking- in most jets the spoilers will accomplish this and the big barn doors hanging down will be useful in slowing down)

 

[frenchy]

the use of full flaps depends on the runway, the wind, your fcom,
if you are going to LGA you will land with full flaps, FLL it is up to you 28 or 40.

 

[Saabslime]

On the Saab 340, we have flaps 7, 15, 20, and 35. The A models horizontal stab had some unpleasant characteristics with flaps 35 and residual ice so they installed a metal plate that blocked the flap handle from going to full flaps.

The B models were redesigned with a wider horizontal stab so full flaps and residual ice no longer posed a problem. The company I fly for operates both models and to keep the profiles the same fleet wide, we only go to flaps 20 for landing. This is the reason our ref speeds are more in line with a jet vs. a turboprop. Its all in how your company wants their aircraft operated. You could have three different carriers flying the exact same equipment and each one will have their own way of doing things.

 

[typhoonpilot]

There used to be ( and maybe still is ) an FAR or AIM paragraph that indicated it was required to use the minimum flap setting necessary for landing. I just spent some time looking but couldn't find it. Maybe AVBUG can help find that.

In the 737, per my company manual, " Flaps 30 is the recommended landing flap when landing on runways greater than 6000 ' in length with good braking action for noise and fuel considerations. Flaps 40 should be considered when landing on runways less than 6000 ', or on contaminated runways with braking action less than good in order to reduce Vref speeds, landing distance and brake wear. "

That said, Flaps 40 does cause considersbly more buffeting around the flaps.

I'm also familiar with China Northern procedures on the MD-80 and MD-90. They land will full flaps, ( 40 ), as a matter of normal procedure. Noise not being a real concern for the government in Communist China. At Far Eastern Air Transport in Taiwan they use Flaps 28, the minimum setting, for their normal procedures.

Hope that helps,

Typhoonpilot

 

[RockyMnt1]

Full Flaps

Moving the discussion to light aircraft, I would not recommend full flaps on high wing aircraft landing in strong/gusty cross winds especially at high altitude airports. The flaps will just add to the tendancy to "weathervane" into the wind once on the ground. Also the downwind flap will be affected differently by the relative wind than the upwind flap so there may be some unexpected asymetrical lift at exactly the wrong time. The use of full flaps would also delay obtaining a positive rate of climb as they are retracted, although not to a great extent.

The C-182 that I fly indicates that stall speed is not reduced at all beyond 20 degrees of flaps.

Unless you need the extra drag or have a short strip or your plane lands at a slower speed (to save tire wear)with full flaps, leave 'em up.

 

[JetPilot500]

The big benefit of landing with a reduced flap setting in a big crosswind is to increase the effectiveness of the rudder. If you reduce your flap setting your approach and touchdown speed will be higher. The faster you are going the more effective your rudder will be due to the additional airflow over the surface.

In larger airplanes, such as jets, full flap landings are usually recommended due to brake energy considerations. Also, the slower you touchdown, the less you need to decellerate on the ground which means longer brake life.

JetPilot500

 

[boxcar]

Every airplane with flaps has an approved landing flap configuration. On some airplanes, more than one flap position is approved for landing. In those airplanes, landing with the minimum flap authorized is sometimes required by noise regulations. However, landing with less than the AFM minimum flap setting just isn't going to happen in a transport-category airplane unless some other factor (such as an emergency procedure) dictates it. Most light airplanes are easier to land with partial or no flaps, (because flare timing is less critical), and some pilots do this routinely instead of learning how to land with flaps.

 

[Joseph II]

Maybe a dumb question...

If you land with full flaps in a large aircraft, the noise problems everyone is talking about is due to the added thrust required to keep the plane in the air correct?

At first I thought the flaps themselves generated the noise, but then I had to laugh at the idea...

 

[skyking1976]

The King Air 300/350 has not been approved to land with anything less than full down flap. This is due to the AFM having landing performance data on the flaps "down" setting only. There are stuck flap approach speeds but those are emergency procedures only.

Skyking

 

[FastCargo]

Flaps...

DC-10s at FedEx have 2 landing flap settings, 35 and 50.

I'd say about 3 of 4 landings have been at 35 flap. From what I have noticed (not being in either front seat yet), the aircraft seems to have crisper handling (less wallowing) when the flaps are at 35 vs 50.

Also, typically we only save about 5 kts going to 50 flap. We usually only use it on either Captains discretion (usually if landing distance is close) or on DC-10-10s, if the landing weight will exceed 363,500 lbs.

My .02

FastCargo

 

[RockyMnt1]

Flaps

Joseph II,

It is my understanding that landing approaches in transport category aircraft are all "power on" approaches. Turbine engines just don't respond to power changes as rapidly as piston engines. There is a time lag between the movement of power levers and turbine engine response. So there are few, if any, idle thrust jet landings (except emergencies).

I am out of my element here so correct me if I am wrong. I'll let the experts take over from here...

 

[350DRIVER]

Rely on your "specific" POH for the exact flap settings and suggestions. IF a flight manual or POH does not require FULL flaps on each and every landing then if I am the PF then it is my call and depending on the landing weight and winds I will decide from there. "Suggestions" are just that nothing more and nothing less however a requirement per the flight manual is not up for debate and you should follow it. The 3 & 350 are a must for the obvious reasons. Contrary to popular belief the B100 with the Garrett's I have found are easier to grease on with full flaps in high wind situations as well as crosswinds versus landing with partial flaps.

3 5 0

 

[Salty Dog]

Great thread as I have a similar question about light a/c. When first learning to fly 150/172 I always used full flaps. With a new instructor he sugguested only half flaps as the landing roll in the 172 is still under 1000 feet yet initial climb performance in the event of a go-around is vastly superior.

Just curious what others have been told or seen as a best practice. Book just says as required.

 

[bobbysamd]

172 landings

Full flap landings during a crosswind in a 172 are a challenge, at best. I always had better luck with half flaps or no flaps at all.

I remember the POH for the 172 in which I learned was coy about the subject. "Use the minimum flap setting for the runway length," or something like that. Maybe I should mention that the 172 I was flying was an older model with the ASI calibrated in mph and provided a POH that looked more like a pamphlet than the POHs of today.

That same 172 had 40-degrees of flaps. So, if you used full flaps in that airplane for a normal landing you were really spooling up the engine. 30-degrees or even 20-degrees were better.

As RockyMnt1 points out, you must differentiate between a 172 and a transport-category airplane. The techniques are bound to be different.