So, Heathrow........

Stuey1

The noise level presumably wouldn't be increased just the number of times the noises are heard. While planes clearly aren't silent they are significantly quieter than in times gone by, and I'm relatively sure that an aeroplane will rarely if ever be using full thrust on climb-out or for landing. (maybe different if you live literally on the edge of the new runway as the thrust will be used mostly while on the ground to get up to speed or slow down) and looking at the plans it doesn't look like there are that many properties in close proximity

And reading the link below it would seem feasible that there wouldn't be a significant change in noise as i would guess low level holding patterns are a more constant noise factor than straight up take-offs and landings

Modernising UK airspace | Noise | Heathrow

Also this ignores any potential benefits (to house prices) of being located near to a major airport with however many thousands of jobs. I think they would have a better argument if they were building a new airport there, the fact is there is a major (the busiest in the UK) airport already on their doorstep so I find it unlikely the house prices will drop too much based on another runway.

IronGiant

I think the number of days a year the Estuary is swamped by fog was another.

Like at the other end of HS2 ?  

Oswald

Good point.  Why not build the extra runway in Birmingham or Manchester, and let people whizz up there from London on the wonderful HS2?  Both airports are already planned to be on the HS2 network, and just think of the benefits to the 'regions' (which was part of the justification for HS2).  

Cliff

Rail prices are so high it would be cheaper to get a flight from London to Birmingham

woody10381

They won't be on full power all the way up to cruising altitude, but they'll generally be using maximum thrust from take-off up to the point at which full power is no longer required to maintain the required climb gradient. This will generally coincide with reaching 5,000ft - 10,000ft so it will still be noisy for those under the flight path.

You're correct in that just-above-idle will be used during the decent but thrust-reversers will still kick out a lot of noise when deployed on landing.

Stuey1

Planes don't always use full power on take off depending on the weight and length of runway available, the power will usually be reduced not long after leaving the ground, this is noticeable whenever you fly. I understand that pilots calculate the amount of power required for takeoff and program this into the Flight Management Computers before take off - the idea being that if full power is not required it puts less stress on the engine and reduces the chances of a failure. It's called a derated take off.

https://www.google.co.uk/amp/amp.usatoday.com/story/2012995/?client=safari

Twin engined planes can climb out safely on a single engine (a requirement for certification), so full power would not be required for a plane climbing on both engines. The only times I can think of the plane will be even close to full thrust (max noise) is on the runway for take off (if heavy) and maybe with thrust reverses (which are noisy) but I'm not sure that utilises full thrust.

Sonic67

They don't use maximum thrust on take off. Also aircraft are more efficient and designed to be quieter than the past.

From Quora.

Do the engines of a plane produce their maximum thrust during take-off?

Aviation

Doug Hanchard, Aviator with 7,000  hours CPL, ATPL Pitt S1 to DC-8's and B-707's.

Historically, they did. Today, modern engine management technology allows both propeller and turbine engines to be controlled to a power setting sufficient for takeoff.

The flight deck crew will input calculated aircraft weight, weather conditions, Runway length, etc, which can then analyze how much power is required for a safe take off.

The pilot in command can over ride this setting and select maximum power of desired.

If the aircraft is only 50% full, and has before them a 10,000' long Runway with a 50 knot headwind straight down the runway, it makes little sense to burn 10-15% more fuel than required by applying full power if it's not needed.

Back in my day flying old turbojet freighters, we didn't have these kinds of options and always used full throttle because that's what the approved flight manual take off procedure called for with no exceptions.

Enki

Surely the powers can insist on more environmentally efficient and lower on the decibels aircraft using Heathrow. So to reduce impact.
Of course what this runway won't reduce is the effect on house prices in certain price bands. It will holt the further march of gentrification's in the surrounding areas.  Being home for many years, NW Surrey, just as it's been in the past with any extension of Heathrow, this locally is about well financed well educated well connected people looking after their sole interests and will happily disadvantage others in their pursuit self interest, it's archetypal British nimbyism.

woody10381

Yes - agree with both points above - I was considering a worst case example with limited safety margin (i.e. hot, heavy, zero wind, short runway), guess I didnt make that clear. Obviously not representative of every departure out of Heathrow but nevertheless a 'high' power setting will always be used until the aircraft is in a stabilised climb and has been 'cleaned up' (i.e. landing gear, slats, flaps, etc, all retracted).

Derated take-offs are conducted only when the appropriate safety-margins exist.

Stuey1

Yes, but runways at Heathrow are likely to be long enough for the safety margins to exist on most occasions (although I'm not sure of the proposed length of the new one -  but both of the others are over 3500 metres) - Which is long enough that in reasonable weather the planes would rarely need to use full power on take off and also wouldn't necessarily even use reverse thrust on landing

Also, this is while on the ground, once airborne the thrust will be reduced to maintain a climb but it will not be full power.

There is no doubting that there is noise from aircraft, but I just don't buy that a 3rd runway will significantly affect anybody noise wise, it is already one of the busiest airports in the world so there is already noise happening.