London airports - T5, 3rd runway, Biggin Hill crash etc.

Why do we persist in flying planes over urban areas? Heathrow airport is sited so that planes either come in to land by flying over central London and along the Thames or take of and then fly over north west London. The addition of a third runway at Heathrow would increase this traffic and spread it over more of north west London and its environs. Gatwick airport, whilst stupidly located in a fog prone area, causes less low level overflying of urban areas but can be run no harder. The same can be said to a lesser degree of Luton and Stanstead. The recent plane crashes or near crashes at Heathrow and near Biggin Hill should act as a warning to us all; planes should take off towards and land from areas of as low population as possible. This is not possible at Heathrow so further expansion should not be permitted, instead limited expansion of Stanstead and Luton should be encouraged but even more importantly the building of an airport on the Thames Estuary should be where money and effort should be concentrated.