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readytotaxi
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LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 11:50 am

Source-London Sunday Times.

Head of NATS Richard Deakin working on a proposal to increase approach angle to 5.5 degrees to reduce noise levels.

Approach


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kaitak
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 11:58 am

I think he's on the right track; I have always thought this could be a possibility; anything that can allay fears over extra noise is welcome.
 
shankly
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 1:25 pm

Would be great if this also freed up some of the vertical airspace for a bit more class G for us span canners around London....although I doubt it. Good suggestion from NATS
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Got2fly
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 2:45 pm

5.5 degrees sounds awfully steep for the majority of traffic into LHR. Do you think they meant to say 5.5 percent?
 
ajd1992
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 3:10 pm

Quoting Got2fly (Reply 3):

5.5 degrees sounds awfully steep for the majority of traffic into LHR. Do you think they meant to say 5.5 percent?

5.5 degrees isn't too bad. It's the same as the approach into LCY - it's only another 2.5 degrees.
 
bond007
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 3:15 pm

Quoting Got2fly (Reply 3):
Do you think they meant to say 5.5 percent?

That's less than 3% isn't it ??

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airproxx
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 3:36 pm

5.5 Degrees seem a bit much for heavy jets, but a good 4.5 could be done easily...
I think about MRS, the ILS 31R is calibrated at 4 degrees and it's easily done by big jets such as A340s or 777s..  
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Got2fly
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 3:38 pm

I think 5.5 percent is about a 3.25 degree glideslope. However maths is not my strong point so I apologise if I am wrong!

Although 5.5 degrees is the same as London City don't the aircraft need to be certified?

We fly to Bodrum where there is a 3.9 degree glideslope and often to ensure you are stable at 1000 ft you need to fully configure before intercepting the glide. A tailwind on this approach can often make it quite interesting.

I'm not saying this couldn't happen at LHR (a 5.5 degree slope) however would this cause other problems such as a decrease in capacity as aircraft will have to slow down earlier and unstable approaches, particularly if any tailwind?
 
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Web500sjc
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 3:40 pm

Quoting ajd1992 (Reply 4):

I realize its only another 2.5 degrees, but I think the aircraft that fly into LCY have to be configured specially. I think the a318 have a special flight mode for that specific approach angle...how would that figure into the proposed plans?

From Wikipedia


Steep approach capability

In March 2006 the European Aviation Safety Agency (EASA) certificated a modified control software enhancement to the Airbus A318 designed to allow the aircraft to perform steep approaches.[13] The aircraft is the largest commercial aircraft certified by EASA for steep approach operations.[4] The software modifies the control laws of the aircraft when the steep approach function is selected by the crew, by automatically deploying some of the spoiler panels to provide additional drag when the aircraft is in the landing configuration.[13] It also provides alternative aural alerts to the crew and modifies spoiler deployment automatically below 120 feet (37 m) on landing.[13] The A318 steep approach procedure allows the aircraft to perform approaches at descent angles of up to 5.5°, as opposed to the standard 3° for a normal approach.[4]

[Edited 2012-12-09 07:41:56]

Edited unneeded picture caption from quote and added link to article

http://en.wikipedia.org/wiki/Airbus_A318#Further_developments


[Edited 2012-12-09 07:43:18]
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waly777
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 4:16 pm

A 5.5 degree slope is much too steep for any Jet, all the Jets at LCY have to be specially configured to fly an approach that steep. Most aircraft will start to gain speed if they are descending that steeply, not to mention the difficulties in changing flaring heights and the additional training costs as pilots would have to be retrained to fly into LHR.

I think introducing an 800 metre to 1000 metre displaced threshold (both LHR's runways are almost 4000 metres long) in addition to a 4.0 degree slope should achieve higher heights over the surrounding towns, thereby reducing noise and also not requiring any additional training for the pilots.
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RayChuang
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 4:17 pm

While a 5 degree glide slope is doable, I do worry about the additional stress on the airframe on such a glide slope, especially when "pulling out" of such a steep descent before landing.
 
lhrnue
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 4:37 pm

Would a 5 degree glide slope make it more difficult for pilots to keep the short distance between aircraft on approach into LHR?
I always wonder how they do it today. Are pilots getting advise regarding speed from NATS?
 
Geo772
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 4:58 pm

Quoting web500sjc (Reply 8):
Quoting waly777 (Reply 9):

The A318 steep descent mode really alters the way the aircraft is configured. Not only are some spoilers deployed, but also the engines spool up as well. Having flown it on the sim it is considerably more challenging than a regular approach. I very much doubt that much larger aircraft could do such an approach.
I reckon that 4 degrees would be more acceptable. A displaced threshold is also certainly a possibility in my view, although it would render some of the exits currently used useless, thus causing some ground congestion that would have to be overcome.

While all these ideas sound great, LHR and the airlines that use it would almost certainly want something in return for these changes.
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airproxx
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 5:10 pm

Quoting waly777 (Reply 9):
A 5.5 degree slope is much too steep for any Jet, all the Jets at LCY have to be specially configured to fly an approach that steep. Most aircraft will start to gain speed if they are descending that steeply, not to mention the difficulties in changing flaring heights and the additional training costs as pilots would have to be retrained to fly into LHR.

I think introducing an 800 metre to 1000 metre displaced threshold (both LHR's runways are almost 4000 metres long) in addition to a 4.0 degree slope should achieve higher heights over the surrounding towns, thereby reducing noise and also not requiring any additional training for the pilots.

Yep, I fly it on a regular basis to MRS, and a 4° slope is a far more doable thing.
But even at 4°, as someone said, the aircraft must be configured sooner, with a certain amount of drag added before intercepting the G/S. So such a configuration at LHR would add ATC and capacity problem. LHR doesn't need it really!
I really hardly see it doable by a 747 or an A380 (rather common LHR visitors) on a 5.5° slope! I tried it on Flight Sim, and the result was... well... arguable...!...

Sounds like a "calming down the crowds" article, than a really feasible idea to me, even if I always believed that steeper approach may be a good answer to fuel burn and noise chase...
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Mir
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 5:46 pm

Quoting ajd1992 (Reply 4):
5.5 degrees isn't too bad.

It's a huge difference from 3 degrees (almost twice as steep). Most of the planes that go into LHR aren't even capable of doing an approach that steep.

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kaitak
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 6:03 pm

Quoting waly777 (Reply 9):
A 5.5 degree slope is much too steep for any Jet, all the Jets at LCY have to be specially configured to fly an approach that steep. Most aircraft will start to gain speed if they are descending that steeply, not to mention the difficulties in changing flaring heights and the additional training costs as pilots would have to be retrained to fly into LHR.

On the Airbus types, there is a selection that pilots can make of FPA, or Flight Path Angle; what is the maximum that can be selected? In terms of descent rate (feet per minute), what's the difference between a 3 degree angle and a 5.5 degree angle.

Presumably someone like the head of NATS would be sufficiently aware of the capabilities of modern aircraft not to make this suggestion if it wasn't technically viable?
 
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readytotaxi
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 6:19 pm

Quoting kaitak (Reply 15):
Presumably someone like the head of NATS would be sufficiently aware of the capabilities of modern aircraft not to make this suggestion if it wasn't technically viable?

That's what I was wondering, why go this far down the line and go public if it is not do-able?
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Got2fly
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 6:24 pm

@kaitak

Hi

If my maths are right a 3.0 degree glideslope at 140 kts will give a rate of descent of 743 ft/min. On a 5.5 degree glideslope at 140 kts then the rate of descent increases to 1365 ft/min. As many have said this will not work well on most jet aircraft even using all drag devices.
 
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Stitch
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 6:27 pm

Quoting airproxx (Reply 13):
I really hardly see it doable by a 747 or an A380 (rather common LHR visitors) on a 5.5° slope!

Considering how quiet the A380-800, 747-8, 787 (and, presumably, the A350) are compared to their older peers on approach, would they not already provide much of the benefit of a 5.5 degree descent slope when following the current 3 degree slops?
 
Cactus105
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 6:28 pm

Quoting kaitak (Reply 15):
In terms of descent rate (feet per minute), what's the difference between a 3 degree angle and a 5.5 degree angle.

For a 3 degree approach angle, a general rule of thumb is 1000 or so for every 3 NM. At 10 NM out, an altitude of roughly 3000 AGL will give you a pretty good intercept to the G/S. So, at 140 Kt. Groundspeed, thatll give you somewhere around a -800 FPM descent. I would assume then, that a 5.5 degree glideslope would give rise to FPM values in the -15 or -1600 range. Of course, with higher groundspeeds, this value increases. These are just estimates, I'd have to do the math, but you get the gist of it. -1500 FPM isn't too bad, but like i said, thats at 140 kts. Some A/C (the 738 & 739 come to mind) the ground speeds may be quite a bit higher, especially when 5 or 10 knots are added to the approach speed for adverse conditions, etc. This could result in Vertical speeds nearing -2000, which IMO is a bit much for a precision approach. Just my    .

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peterinlisbon
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 7:03 pm

5.5 sounds like too much but maybe a small increase, to something like 3.5 or 4.0 would work. However, I think that would add a lot of complication to Heathrow operations with some aircraft coming in too fast and having to go around and it also adds a certain amount of uncessary danger (a more difficult and less stable approach with less time to level off and more chance of going off the end of the runway). Some of the reduction in noise would come from lower thrust rather than the difference in height.

Anyway, the airport has been around for a long enough and people knew it was there when they bought their houses. It's also been operating at full capacity for many years now, so people can't really complain that the noise has got worse. If you buy a house next to a railway line or a motorway, is it ok to then campaign to have the road or railway closed down? So why, when someone choses to live next to an airport is it ok for them to try to stop the airport from operating because they don't like the noise?

I think that noise these days has become less of an issue anway as noise levels are now much lower than they were 10-20 years ago because the planes have got quieter, concorde has been retired etc. I remember about ten years ago when the observation deck was open and the difference between that sound that a 747-200 used to make and the 747-400 was incredible. And Concorde could be heard 10 miles away when it applied reverse thrust. Now even the 744 is being replaced by A380s which are even quieter.
 
airproxx
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 7:55 pm

Quoting Stitch (Reply 18):
Considering how quiet the A380-800, 747-8, 787 (and, presumably, the A350) are compared to their older peers on approach, would they not already provide much of the benefit of a 5.5 degree descent slope when following the current 3 degree slops?

Yes, you have a point here. Modern jetliners are already very quiet, even in approach phases, and I doubt a 5.5° slope would lower the noise that much, comparing to existing slopes. To me, the most benefits comes from the higher height when overflying suburbs...
Plus most airports now request pilots to perform a "low noise, low drag approach": retarding as long as possible flaps and gear extension...
Maybe it'd be clever to remind these parameters to those ever-yelling residents? If you don't like airports disturbances, go live somewhere else! Please!!
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fcogafa
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 8:44 pm

Not w9rking at the coalface. Upper management have little idea of the realities of their suggestions. So don't expect this ide% to be any more than a soundbite to appease the nimbys...
 
Mir
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RE: LHR, Nats Propose New Steeper Decents.

Sun Dec 09, 2012 10:18 pm

Quoting airproxx (Reply 21):
Plus most airports now request pilots to perform a "low noise, low drag approach": retarding as long as possible flaps and gear extension...

Which would not be able to happen with a steep glideslope. You'd have to get the gear and flaps out early (and use full flaps instead of a reduced setting), which would cancel out some of the noise reduction.

-Mir
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