BA 747-400 APPROACH AT LHR

[747FOCAL]

I HEARD BA CHANGED THE APPROACH CONFIGURATION FROM WHAT BOEING INTENDED? JUST KIND OF CURIOUS AS TO HOW AND WHY? :p

[OneDotLow]

Care to elaborate?

ODL :)

[747FOCAL]

Cause either they are landing light or something else to get their noise numbers that much better than operators of the same airframe/engine combo. :D

[TopBunk]

747MAN

Maybe you refer to the practice of using Flap 25 as the usual land flap setting, rather than Flap 30, when there are no performance reasons that require the use of Flap 30?

This would result in lower noise levels, when compared to an operator using Flap 30 at a given weight.

[Barnburner]

;) Flap 25 is also useful to get onto the 1st tee quicker.

Sorry - couldn't resist. :eek:

[GlueBall]

Flap 25 landings NOT recommended by the manufacturer, according to QF-01 accident report (BKK).

[jtr]

Barn, probably part of a small audience, but it did bring a grin.

[Barnburner]

For normal situations that is true. For a variety of non-normal situations you have to use flap 25. One example is whenever Vref is above 167 KIAS (overweight landing) flap 25 must be used to avoid the possibility of flap relief operating. Flap 30 Max KIAS is 180.

Flap 25 still remains approved for a normal landing and is still used by Qantas on some occasions.

[747FOCAL]

I would suggest using Flap 25 as often as possible at LHR.

[Ford Airlane]

And why is that?

[747FOCAL]

Think of the noise you generate operating an aircraft like water filling a glass. Well with the new monitor schemes they are coming up with that start in April each airline will get their "glass" and once full you aren't operating at that airport till you get your glass next year. :)

[747FOCAL]

10%???? Nope. maybe 5.5 - 7%..... So how are those CDA procedures treating you over there anyway?

My takeoff stuff is almost ready as well. estimated Vlof of 747-400 at 875,000 lbs is approx 200+ kts. And then there is thrust management..... That your really gonna love. :)

[mutt]

747FOCAL,

What new monitor schemes are you talking about for LHR? Could you point me towards a official document about them?

Thanks.

Mutt

[747FOCAL]

Hi Mutt. I don't think they are adding any new monitors. K**** M***** and crew are just gaining more faith in their ability to accurately measure operational noise and start handing out infractions and gathering fuduciary evidence that could be used legally.

If you understand the noise game, which I assume you do, you know that the what, how and when is all over the board. 747s being the tent pole aircraft, well besides the 727s are going to continually get more and more attention. I was suggesting that the operators should do everything that can be safely done to get as much shine off there butt before it gets really hot. I can't tell you who I am and what I do, but trust me, I can see things coming that G** R****** and crew are bringing that is gonna kill some of the little operators and badly hurt the big ones.

Can you believe that there will actually still be non re engine 727s still flying in and out of LHR after April 1 this year? Some have my hushkit on them thanks to Article 84. :)

Sorry decided to get rid of the regulators names yest they get attacked.

[ 09 January 2002: Message edited by: 747FOCAL ]

[ 09 January 2002: Message edited by: 747FOCAL ]</p>

[mutt]

747FOCAL

I unfortunately have to understand the noise game, but I haven’t got a clue as to what you are talking about <img src="smile.gif" border="0">

suggesting that the operators should do everything that can be safely done to get as much shine off there butt before it gets really hot.

Can you spell it out a little bit more clearly!

Thanks.

Mutt. http://www.stopstart.fsnet.co.uk/mica/FarSMutt.gif

[747FOCAL]

I guess that was also a bit crass. I just have put some real time into long technical discussions on here and then get flamed for it.

All airlines have to be noise conscious these days. Problem is, most really want to lower their levels, but few understand how to operationally do it. I won't preach to the choir and explain all the many things that can and do affect the perceived noise of large aircraft. Things are tightening up, everyday there are more politicians screaming about airport noise.

We have made great leaps in reduction since the 70s, but the reductions are getting smaller and smaller. The airports have to be able to show regular reductions in the amount of noise leveled on any one area to at least appear they are doing something.

The old days of save your tires and brakes by landing at lower speeds at max flap are soon going to be failing the cost equation. Airports will have to pass on the cost of a wider area of noise suppression installations in homes to the airlines if they start losing court battles. All those 747s landing at LHR makes that place especially targeted.

Without looking I am not sure how many operations into LHR happen a day for 747s. I do know there is approximately a 2 dB difference in EPNL levels flaps 25 vs 30 on a 747. On the older ones it can be as much as 3 dB.

Using 2 dB, a crude calculation of an airline choosing to operate at Flaps 25 vs 30 would reduce it's operational noise dump by 2%. Doesn't sound like much, but it will add up fast as more and more operators follow suit, if they do. Hence the glass takes longer to fill.

The flaps 25 for 747s is just one small step. There is much more they could do that is not suggested by the manufacturer and should be mandated by the FAR/JAR regulations.

If airlines had to regularly qualify the acoustic configuration or condition of their airplanes they would become more conscious of the vast number of things that can reduce operational noise levels. Things they are already doing on a day to day basis. They just need to be shown how doing maintenance one way vs another can help or hurt the acoustic configuration of their aircraft. Even if it wasn’t forced I think they would be doing some of these things anyway. They just need to be taught how to look at how they acoustically maintain their aircraft. I know that an aircraft in poor acoustic shape can lose as much as 40% of it’s delivered ability to meet the FAR 36 Certified noise levels.

I can walk around an airplane and tell by looking if the plane has any chance of passing a test to see if it still meets what it was certified to noisewise. Let me look at the maintenance records and I can tell a lot more.

Aircraft are noise certified at constant thrust. The majority of aircraft today are landing with auto throttles on and is one reason why monitors show higher noise levels than cert. How conscious a pilot is to how he flies the airplane and how it affects monitored noise levels is another. Pilot input to controls and aircraft maintenance affects how much the auto throttle has to work(move around). If it is constantly jumping around chances are it is bumping the engines to maintain speed. The more it bumps the more noise the engine dumps. This can be helped.

I kinda rambled on past the intent of what I wanted here. Sorry if it was too boring.

Time for bed.

[mutt]

I find your comments interesting rather than boring especially the part about

I can walk around an airplane and tell by looking if the plane has any chance of passing a test to see if it still meets what it was certified to noisewise. Let me look at the maintenance records and I can tell a lot more.

What exactly are you looking for during the walkaround?

Noise is becoming a right P.I.T.A. the days when we were able to say we are Stage 3 are long gone. We are now getting forced to do aerial gymnastics to avoid noise monitors with takeoff procedures based on the location of the monitor rather than normal procedures.

I wish that the airline industry was as powerful as the noise lobbyists, the industry has achieved wonders in the last 20 years, has any other part of the transport industry achieved so much ?.

Mutt. <img src="smile.gif" border="0">

[Ford Airlane]

I must say that some of what 747focal said has confused me particularly the "I can tell how noisy a plane is by looking at it" bit, however,

[paragraph relating to deleted posts removed - Checkboard]

747FOCAL - you wrote - "The old days of save your tires and brakes by landing at lower speeds at max flap are soon going to be failing the cost equation"

You are wrong in inferring that flap 30 is preferred on economic grounds. In fact the beancounters like it when pilots use Flap 25 for the following reasons:

- less flap wear and tear; &
- less fuel used; &
- the energy absorption characteristics of the carbon brakes on the 400 make it preferable to have a few high energy applications than frequent low energy ones i.e. using flap 25 you get better wear out of the brakes, particularly if used in conjunction with idle reverse.

In Qantas' case I believe the savings from Flap 25/idle reverse were a million (AUD) a year on brake pads alone.

I can't comment for the entire 400 community, but I don't see many manual landings with the autothrottle being used. As you correctly point out, any speed off bugged speed causes the autothrottle to 'hunt' which causes an annoying pitch up/down moment (when manually flying) that can throw you off profile easily. It is much easier to control the thrust manually when flying manually.

I am no great expert on noise abatement, but I would have thought takeoff would have been the more critical noise event?

As with anything, the final decision to use a particular flap setting rests with the pilot in command. The major considerations are aircraft weight, density altitude, wind, flap setting (25 or 30), full/idle reverse, visibility, landing distance available, slope and runway contamination. Also, a non-normal configuration may have an effect on landing flap setting. There may be others (e.g. visual/electronic approach slope guidance availability) I have left out.

Should these factors tally in favour of a flap 25 landing then that is probably what most would choose. Any noise policy would be considered AFTER the above factors had been taken into account. As an example, Jo-burg has a "we prefer idle reverse thrust on landing" clause on their noise pages in Jeppesen, but I don't know of many 400 pilots who use less than flap 30/full reverse on a hot day there given that JNB is a mile above sea level.

It certainly doesn't take much to push the equation in favour of flap 30 e.g. low visibility or contaminated runway, both common at LHR.

Safety is the primary consideration, then noise abatement. As it should be.

<img src="smile.gif" border="0">

[ 13 January 2002: Message edited by: Checkboard ]</p>

[747FOCAL]

Ford Airlane - I can appreciate your confusion because the noise game can be quite confusing.

411A- I agree with Mutt we are professionals I will back off. We are, thanks to the efforts and sacrefices of many, free to our opinion.

The noise vs safety issue has become a very heated arguement. Mutt talks about new take off procedures that push the limits of safety. I myself have asked why are we doing this? But, I must look on the history of aviation and what an excellent track record we have. I stil don't like sacrificing safety for reducing the amount of noise being dumped on a person that is safe on the ground and chode to move next to an airport. But, this is the career I have chosen.....

Mutt- I am trying to start helping airlines reduce their operational costs from noise by teaching them how to look for what I am talking about. Problem is these things are relatively simple and I don't want to give up my secrets. Hence, I want to get paid for the costr savings they get.

If you work for an airline that is looking for this type of help I am available in about 4-5 weeks.

[747FOCAL]

Ford Airlane - I forgot to continue my thoughts on your comments.... You offer insight that is very valuable to me and I will sure to make note and share it with my colleagues. This information is in the true spirit of this thread and this forum. If you can offer insight into either BA or Qantas avg landing weights at LHR I am most interested. I have heard that Qantas avg 250 kilos.

Thanks for you informative comments.

I will look for more from you.

Cheers!

[747FOCAL]

Ford Airlane - Sorry for the third post but I can't edit from here.

On a 747-400 takeoff EPNL is about 99.8 dB @ 875,000 on approach flap 30 it is 103.8 at 652,00 and 102.1 flap 25. 747-200s at 630,00 are 105.9. Concorde on takeoff is about 120 dB if that helps.

[mutt]

Michael B,

I'm not sure how these will format, but if you take the data into an excel page you should be able to compare the certified levels for these aircraft, I'm sorry but I dont have the DC-10 data.

Airplane/Engine/
Weight lbs/ WeightKgs/Flap/Takeoff/Sideline/Approach EPNdB

MD-11F/CF6-80C2D1F
Takeoff 630,500/285,990/10/94.7/96.2/---
Landing 481,500/218,405/50/---/---/104.5

B747-200&300/RB211-524D4/
Takeoff 833,000/377,842/10/104.1/99.7/---
Landing 630,000/285,762/30/---/---/104.9

B747-400/CF6-80C2B5F/
Takeoff 870,000/394,625/10/97.4/100.3/---
Landing 652,000/295,742/30/---/---/103.7

B727-100 JT8D-9A (Hushkitted)
Takeoff 169,500/76,883/5/94.0/97.3/---
Landing 142,500/64,637/30/---/---/98.8


747FOCAL, our rules are easy, we will listen to any presentation from a company, but not an individual, which class do you fall into?


Mutt.

[Edited for typos]

[ 13 January 2002: Message edited by: mutt ]</p>

[747FOCAL]

Mutt-Well, I work for a big company that is fast making itself smaller and I have my own. You would not be getting the rantings of a private citizen. I am sure once my credentials are looked over you will have no doubts as to my background and abilities.

Michael B - I am at home and cannot give you exact levels. Mutt's look correct. Were you asking about a 747-200 or a -400? I can guarantee you that an old JT9D-7 will leave a lasting impression on what you think is noisey.

But, to answer your question.... The Large Antenov(spelling) family is probably louder. Though being Russian they are exempt from noise requirements. I think the EU is thinking that one over again though.

The big daddy of noise and is also exempt but path restricted ...... Drum roll........

CONCORDE @ 120 dB and I have seen LHR monitor data with it at 125 dB on takeoff. Good that it doesn't stick around long.

[Dan Winterland]

Ford Airlane, use of full reverse thrust will not reduce your landing distance if autobraking is used - and I'm sure that most pilots will use autobraking as per their company SOPs as opposed to manual braking, esp at a hot/high place like Jo'berg. This is beacause autobrakes set a measured decceleration rate as sensed by the IRSs. Application of reverse thrust above idle will result in the IRSs releasing the brakes a bit to maintain the set rate. You will only decrease the landing roll if you manually brake, and this will probably result in increased brake wear on carbon brakes for the reasons stated previously in this thread.

For those who are interested by the boring details, these rates are 2 feet per second/per second for autobrake 1, 3 fps/s for autobrake 2, 4 fps/s for 3 et seq.

[Captain Airclues]

747FOCAL

We (BA) always use Flap 25 at LHR except in Cat 3 conditions when we use Flap 30 as the lower pitch attitude gives better visibility.
We take noise issues very seriously, and train our crews in noise reduction techniques. However, if you have any suggestions for improvement, we are always willing to learn.

Airclues

[Ford Airlane]

Dan,

You are, of course, correct about the measured deceleration rates with autobrakes and contribution of reverse thrust having no effect on actual deceleration rate with autobrakes. I mentioned reverse thrust in the case where autobrakes, for whatever reason, are not used.

Three things are required for the autobrakes to function if they are armed:
1. Ground mode sensed; &
2. Thrust levers at idle on ALL engines; &
3. Wheel spinup has occurred.

I highlighted the "ALL" in nr 2 as in the case of Qantas 1 at BKK the autobrakes disarmed very early in the landing roll as , I believe, the nr 1 thrust lever was advanced slightly out of idle, disarming the autobrakes. Full reverse thrust, in this case, would have reduced the distance used.

747FOCAL, 250 kilos sounds a touch light, I assume you mean 250,000!! 250t is probably a little heavier than most Qantas aircraft land at LHR. I would think avg landing weight would be closer to 240. Don't quote me on that.

<img src="smile.gif" border="0">

[747FOCAL]

I appreciate the info and Captain I will be approaching airlines in the future in the hopes of "prying my wares" and teach techniques that can when appplied correctly lower operational noise levels.

If 240 tons is the average landing weight for Qantas at LHR from home then I got work to do.

[Ozgrade3]

Just how much sirframe noise is generated(as opposed to engine noise) in the following configurations.

1, Clean at 250 kts and 3000' agl and

2, Full flap and gear down at Vref

I have also noticed, that the GE powered 747's are much quieter as they taxi past than the Rolls powered ones. It seems that the exhaust ports on the pylons from the aux numatic hydraulic pumps emit more noise than the engine itself.

[747FOCAL]

Clean the airframe noise is buried in the noise of the engines and would not show up in the measured noise levels. A 747 all engines off, full flap and gear down will register about 101 dB. Give or take a few tenths. It's them fowler flaps that cause the majority of it.