UK air transport capacity and noise - a viewpoint

As the government's promised response to the recent Davies Airports Commisssion draws nearer, Rod MacDonald higlights the need for noise impacts of the reccommended development at Heathrow to be examined more closely.

Antony Oliver
21 September 2015

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The Airports Commission has rightly said that there should be a legally backed noise body to monitor and enforce noise levels around our airports. London First has been promoting such enforcement for a number of years. 

Noise is very difficult to define and the way such enforcement is set up will entail very carful planning.  Different people hear any level or type of noise differently and even a single person will hear noise differently depending upon their state of mind at the time. Defining the limits on noise level and type to be both effective protection for residents and legally binding will be a tricky task and potentially open to avoidance by the industry. 

"Any decision about Heathrow should be made in the knowledge that the noise per aircraft will, apart from the effects of approach descent angles, not reduce significantly for some 50 years."

It is claimed that since the sixties the noise footprints of aircraft have reduced by 60%.  This is very impressive and, as the reduction is mainly in relation to engine noise, firms such as Rolls Royce and Pratt and Whitney  deserve much credit.  The challenge is that this achievement in noise reduction is almost entirely in relation to take-off.  Reduction in approach flight path noise that relates more to aircraft frame noise is much less and, as is shown in the Commission report, current targets for approach noise reduction are not being met.  

It is approach flight path noise that affects most people near Heathrow.

The Airbus 380 has achieved about as much as is possible in noise reduction with current airframe technology. The industry are saying, “In the longer term, after 2050, completely new aircraft geometries that use blended wing designs, and even morphing geometry – aircraft that change shape – will potentially lead to major reductions in airframe noise, greater efficiency and improved environmental impact.”

If we allow a further 15 years for airlines to have purchased such aircraft and use them for the majority of their flights, it will be some 50 years before significant noise reduction can be achieved. The development of such blended wing designs or morphing wing geometry will cost the airframe manufactures millions. 

As most airports around the world are now located with approach flight paths over water or sparsely unoccupied land the pressure on airframe manufactures to do this development is, apart from that from Heathrow, not great.  It is far more urgent to develop and build aircraft with smaller carbon footprints and inevitably this is where the emphasis will be.

"If we allow a further 15 years for airlines to have purchased such aircraft and use them for the majority of their flights, it will be some 50 years before significant noise reduction can be achieved."

The other method of achieving reduction in approach flight path noise is to vary the flight path route or the angle of descent. Varying the flight path route is essentially spreading the noise misery to a wider population.  It is interesting that Heathrow calls this ‘respite’ (essentially short term relief from something nasty). The noise along a particular path may be intermittently reduced, but the aggregate of noise remains the same. 

Changing the angle of descent is a different matter. Essentially if, as could be, the approach descent angles were doubled noise levels would be substantially reduced. The big question is, however, ‘why is this not being done now?’  We should not have to wait for a new runway or a noise enforcement body to instigate this.  It could be bringing partial relief to many residents now.  

Essentially, any decision about Heathrow should be made in the knowledge that the noise per aircraft will, apart from the effects of approach descent angles, not reduce significantly for some 50 years.

Rod MacDonald is an independent consultant, founding partner of Buro Happold and a former chair of ACE