SSR,

So you've never heard of a three engine ferry then? It's just after the chapter about flaps and windshear.

Of course I know what adverse yaw is. I just don't know what it's got to do with this thread, pprune or the moderators.

Oh, don't rise to his bait or we'll be bombarded with more irrelevant nonsense, as if wing warping wasn't bad enough. To guys like SSR there's only ONE way to do something and anything else is just wrong. Flap 25 OR flap 30, don't be so ridiculous. Let's ignore what Boeing do recommend and, instead, suggest other techniques e.g. asymmetric thrust which, for some strange reason, seems to be missing from the manufacturers' manuals.

Never mind that Boeing, British Airways and the CAA all approved the steps taken by the LAX 747 crew and never mind that all 3 on the flight deck went through all those approved steps and decided to do what they did, SSL is telling us they were all wrong and he knows. There's only one way to operate an aircraft and that's SSL's way, with one flap setting, wing warping and asymmetric thrust :rolleyes:

I'm glad between the likes of Stilton, Masher, Gatbus etc we've established that using a reduced flap setting is (a)a perfectly normal means of operating an aircraft safely (b)is approved and recommended by the manufacturers (who seem to know a bit about the subject and (c)helps to achieve what the OP was asking about in the first place.

I think I'll leave it at that, lest the chaff dispensers return.

Just giving him more rope Pontius!

Thanks for the info.

Any drivers of other jet types with info on whether controllability is in their opinion better at a reduced flap setting for strong gusty crosswinds.

On the A320 series I find flaps 3 better for gusty/crosswind etc than flaps full (as per the manual). At the airline I work for SOP is now flaps 3 for approaches if full not required, due to fuel savings.

I have found, in 737, that F30 seems to be easier to control in a gusty crosswind than F40.
On a side note this brings up a question that I've always wondered about and I have received 2 different answers from different people ( so maybe pprune isn't the best place to ask!!) but here it goes. When you're extremely light, ie. positioning an empty aircraft, what's your preferred landing flap? And why? (Assuming runway length, weather, wind etc. isn't a factor)

correct.

honestly, its so obvious for any real pilot with work experience that reducing flap settings to a minimum needed and approved on a gusty day with a strong crosswinds helps a lot and is a common procedure, that basicly in real life nobody from a flight deck would start a debate about it.

so this thread of course went after few postings stupid with no useful information.

the only thing which makes it worth reading is the fun about all the dreamers here who continue to debate in which direction ever and fail to see that seriously debating this obvious question by itself for several days proof them to be very fake and never had a crosswind landing on whatever aircraft.

for a real pilot , even a private one with some hours logged, its not a question if its a better idea to land a cessna 172 with flaps 40 or flaps 20 when a strong and gusty wind from the side blows.

cheers !

With your vast experience at 35 yrs of age guess you must be right. Yes the Cessna 172 lands better with reduced flaps in a gusty wind situation but how has your experience in a Boeing 777 been doing the same thing. I will give you 20 years to answer.

Well at least he's up to date!

Embraer 170+ series, 737 300 and 800, 146 100-300. CRJ 200. All better with reduced flap landings.

Spandex, get over yourself. I know you are number one for you but the rest of us don't GAS.

Nothing to do with me Bubbers. You belittle someone for only being 35 and use sarcasm to refer to his experience, something you know nothing about. On the same thread you claim you have 23,000 hours and 40 years experience but you don't know which are approved flap settings for the aircraft that you claim you used to fly. Yet I am the one who has to get over myself?!

You've been proved wrong on this thread numerous times by numerous posters. Your experience is out of date. I hope you're better at fishing.

Perhaps you should retire gracefully.

"When you're extremely light, ie. positioning an empty aircraft, what's your preferred landing flap? And why? (Assuming runway length, weather, wind etc. isn't a factor)"

I've tried F30 & F40 in these conditions. My initial thoughts were F40 because at light weights the N1% is about the same as F30 i.e. mid 50's. This would give better engine response for speed control. It is definitely better if there is a tailwind otherwise the N1% would be well below 50%.
At F30 I expected N1% to be too low and not give such easy speed control, but in fact it was not too bad.
Suck it and see.

flaps 20 on 757, flaps 15 0n 727 on an engine out approach. No sim checks in over 9 yrs makes these numbers meaningless. Brain cells are meant to handle present day problems, not what age 60 rule said you couldn't fly an airliner any more but try to remember every flap setting you will never use again because you are too old.

I am not bitter about the rule because it was there when I got hired at 35. I just know what I know now vs age 35. Yes, I flew Lear Jets and Jetstars and tons of twins but flying for the airlines was the final learning process that completed my career. It makes you really take your job seriously.

three engine FERRY
 

sure...no problem...but NO "BOOK" authorizes three engine ferry with passengers aboard.

and sure, it might have been legal to fly from LAX to ALMOST London on three...but what about common sense?

keyword ALMOST London. they didn't make it.

Common sense: there's nothing else wrong with the aircraft, even if the aircraft loses another engine all terrain can be covered, there's countless alternate airports enroute if another engine fails, there's sufficient fuel on board to reach a decent airport enroute, it's an approved 'manoeuvre' by the manufacturer, company and safety regulator and, lastly, ALL the crew agree the same thing. There's plenty of common sense in all of that and just because your dyed-in-the-wool thinking won't allow you to think any more than Flap 30 doesn't mean the crew were mistaken in their actions nor worthy of your derisory comments.

No, they didn't make it to London but, guess what Einstein, they KNEW that was going to be the case before they were halfway across the US. Amazingly, even without your expert knowledge being available, they were able to figure out their course of action which ended up with a perfectly safe flight, less inconvenience for the pax and an easier repatriation of the machine. I know you hate anything across 'The Pond' but I reckon the the operator of the largest number of 747-400s in the world might have just an inkling as to what they're doing....even if asymmetric thrust was not part of the syllabus.

Ah, of course not but you didn't qualify your statement before.

No they didn't make London, mainly due to unforecast winds, but Manchester is a lot closer than the states, any of it.

I understand that the FAA rolled over on this.

The FAA rule is if you have two engines and lose one you have to land at the nearest suitable airport. If you have more than two engines you can continue as long as it as safe as landing at the nearest suitable airport. Continuing across the Atlantic was legal by FAA standards as long it was as safe as landing at JFK. You be the judge. I wasn't there so have no opinion.

What's the CAA rule?

Pontius: I suggest you revisit the AAIB report on that flight. They had some very choice observations to make about the then -400 fuel balancing procedures that were in force in BA at that time. (they were at variance to the Boeing procedure) This is what led to the diversion landing short of LHR. The legally required total amount of fuel was indeed still onboard - it just was not in the correct places hence the crew`s concerns. IIRC BA were told to instigate appropriate training plus change their manuals.

(The crew were using the Jettison pumps to maintain balance - this works fine until you get to stand-pipe level...................)

gee spandex...you seem to have made a mistake

oh...and I know its "legal" to do what the crew did...

its legal to do alot of things.

and common sense is not all that common.

so fly the atlantic with one dead, land with any flap setting you like, but just when you have done what's legal, and something unexpected comes up...THINK OF ME, GRINNING.

Errrr what would that be then? Apart from wrestling with pigs.

Why would I do that?

Grinning or gurning?

Loggong in
 

I tried several times to log in using the same password but was unable to. Finally I got in. Is there something wrong with the site????????
How do I contact the webmaster directly if I have a problem????
Thanks.
Thermostat

Flaps on approach
 

I seem to remember that the drag goes up with the square of the lift. If you double lift, the drag goes up four times. Triple lift and the drag goes up NINE times. So the more flap you use, the more lift you produce but the drag goes up quite a bit (with the square of lift). During turbulent approaches, if flap is reduced, drag is also reduced, speed is increased and that helps to improve approach and go-around performance if required.
I well remember the L1011 that crashed going into Dallas years ago. Got into a microburst and couldn't maintain the flight profile. It's possible that a reduction of flap may have saved the day.
T

Meikleour,

I agree 100% regarding the fuel situation and things did change as a result of the incident. To be fair to the crew, at the time, the manuals were not very clear on a couple of the finer points of the fuel system but that has been rectified and I'm confident the situation in which they found themselves would not happen nowadays.

For what it's worth, the incident shouldn't even be in this thread. I only wrote about it because of SSR's bigoted accusation of what they did was wrong, because it doesn't conform to what he would have done. The actual flight has been done to death on PPrune and it's clearly got nothing to do with flap settings, so hopefully that'll be an end to it :ok:

Pontius: Thanks for your reply.

THE LAW OF UNINTENDED CONSEQUENCES

My personal interest in that incident stems from my own experience many, many moons ago when I worked for one of the companies that became BA. Your loyalty to BA is understandable however that company has always had a tendency to change/rewrite perfectly good manufacturer's manuals into their own version. I was very nearly caught out by just such a situation involving an emergency gear extension which did not work as per the BA drill and indeed the poor -400 crew were let down in a similar manner.

I do however draw the line at your assertion that the flight was perfectly safe when in the end the crew felt that they had to declare an emergency!!

Going back to the original thread - the various manufactures go to great lengths to produce operating procedures that work and do not require "exceptional pilot skill" therefore there should be no need to debate the merits or otherwise of different flap settings. I am fully aware that some individuals will always know better however.............

The poor guy that initiated this thread is probably more confused now than the beginning. I would say if the operating manual says you need to or can use discression on flap settings and your op specs agree do what works best for you. I personally usually used the max setting unless performance required otherwise but others feel differently. Never once had a problem using that procedure. As long as it is legal who can fault you?

I think there is lot of argument (some healthy) over this subject as there isn't really a 'right' answer that covers every aircraft type, runway and weather condition.

In no particular order, here are some of the things that might be considered on a bumpy day when choosing a land flap setting in a jet transport:

Advantages of lower flap setting:

* Higher Vref gives greater control authority
* Less drift angle
* Less drag, so better performance in windshear
* Often greater margin to flap limit speed
* More fuel efficient

Disadvantages:

* Longer landing roll
* More variation in speed due less drag
* Engines less responsive as lower thrust setting
* Easier to carry excess speed into the flare
* More energy into the brakes
* Tailstrike more likely in some types

Advantages of higher flap setting:

* Shorter landing roll
* More stable airspeed
* Engines more responsive
* Lower pitch attitude
* More time to adjust flightpath
* Minimises brake temperatures

Disadvantages:

* May need more control application
* Often close to limit/relief speeds in turbulence
* Loss of airspeed in the flare may need prompt action
* Less fuel efficient

If I was landing on a long-ish runway with a headwind component, I'd probably go for the lower flap setting. A wet and/or shorter runway, tail wind, high landing weight and/or high density altitude would have me fully configured. The books usually say I could land with either but I have a strange aversion to planning the use of a large percentage of the available runway if there is an option to use less...

FW, I agree with your analysis. We all have found what works for us and are comfortable and successful using that technique. Why change it because some other pilot finds a different way of doing it works better for him?

Nice post FullWings.

Thought I might add one.

On some aircraft, less flap can mean more difficulty slowing to approach speed while maintaining minimum approach thrust. On the 727-200 with a Raisbeck hushkit and a maximum of Flaps 28, at light weights it was difficult to slow down to approach speed at minimum EPR.

Its been an interesting journey through this thread with some amazing drift off topic, good to see that it's back on track. BARKINGMAD made the best observation some time back. In turbulence and limiting crosswinds its an advantage to reduce flap, where permitted, because the spanwise lift distribution moves outboard and increases roll response. The reduced drag also improves speed recovery in gusts. Try landing at flap 30 in a B777 in turbulence and a circa 40kt crosswind and you can reach full roll input at times. Flap 25 makes it much easier to manage.

Spoiler response V Aileron response
 

I fly the A320 and always use Conf 3 rather than Conf Full in gusty/crosswind conditions, primarily for better controllability.
From what what I have read, Conf Full on Airbus uses a lot of spoiler deflection for roll control, and the response of spoiler deflection is not linear ( unlike aileron deflection ) leading to overcontrolling and PIO.
For myself, Conf 3 with more "normal" aileron response makes the 320 fly like my previous non-FBW types, and makes the gust corrections much easier.
I am not a test pilot, so if another explanation is correct, I would be happy to stand corrected.

Static lateral stability
 

I think that the main advantage of lower flap setting for approach in gusty/ crosswind is slower reaction aircraft on changing in sideslip.
In gusty wind sideslip is continuously fluctuating and aircraft is continuously banking from side to side due to static lateral stability.
(see http://aviacom.ucoz.ru/Book_13_Principles_of_Flight.pdf, Chapter10, page 302)
All contemporary aircrafts have swept wing and this lead to excessive static lateral stability (see pages 306, 307 and figure 10.62).
The more Cl (coefficient of lift) we have - the more "dihedral effect" we have, and we have to counter the more sharp lateral aircraft movements.