Air quality modelling is made more complex by the interactions between different types of air pollution. Aircraft, car and lorry engines trade off NOx and carbon dioxide (CO2) emissions: so as a general rule measures that are good for NOx are bad for CO2 and vice-versa. Operations to reduce aircraft noise also increase NOx emissions and vice-versa. While aircraft engines are subject to NOx emissions standards set by the International Civil Aviation Organisation (ICAO), the CAEP 6 standard will not come into effect until 2010. Whether, when, and by what degree, there will be an international consensus on further stringency is uncertain. While the European Commission is committed to publishing a proposal in 2008 on how to tackle NOx emissions from aircraft that contribute to climate change (many of the options under consideration relate to tackling LTO NOx by proxy), the only measure to incentivise less polluting aircraft is the potential inclusion of aviation in the EU emissions trading scheme (which focuses on carbon emissions). Unless the Commission applies measures to NOx in parallel, it is questionable whether manufacturers will deliver maximum NOx reductions where it impacts on fuel efficiency. The ‘Demonstrating Confidence’ report also notes that:
“For modelling purposes it may well be the case that the conditions leading to the highest concentrations for ground-level sources (e.g. road transport) tend to result in a smaller contribution from aircraft sources and vice-versa. This could make the selection of a ‘best’ and ‘worst’ case meteorological year difficult.” (p.42)
In time, the car/lorry improvements will bring air pollution levels near Heathrow below legal standards, which could lead to better health for people living near the airport. Instead, again, the proposed expansion of Heathrow would take up all this slack.
The only way of being confident that both noise and air pollution criteria can be met at Heathrow is to first bring pollution levels within legal limits, and then to consider the impacts of further capacity using reliable current monitoring data.
RISK AND PUBLIC SAFETY ZONES
Take-offs and landings are the most dangerous phases of aircraft operations. Of the aircraft crashes that have occurred over the past 3 to 4 decades, most have occurred on or relatively close to airport runways. Risk is greatest close to the runway and to a line extending out from the runway centreline.
The consultation report on whether 130 aircraft movements per hour could be accommodated on three runways suggests that this will be “very challenging” (in fact, the term ‘challenging’ is used six times in the two-page executive summary). The report notes that
“there are a number of significant issues still to be addressed before [the air traffic controllers at Heathrow] could express confidence that a fully viable, safe Concept of Operation exists that could meet all the required objectives for the London [Terminal Control Area], accommodate the traffic generated by a third Heathrow runway, and deliver environmental benefit...”