08/07/2013

Hot weather is bad for aircraft and airport neighbours

When the weather is very hot and the air is thinner, aircraft have more difficulty in taking off, and often make more noise.


It was reported last week in the British press that 15 passengers on a Swiss flight from London City airport to Geneva were denied boarding due to safety concerns caused by the hot weather. It appears that this is a recurrent problem for that City airport, where the runway is only 4,900 feet long (Geneva runway is very much longer), when the weather is very hot. The air is less dense and so gives a reduced lift factor, meaning that the takeoff speed has to be higher.

Swiss is apparently not the only airline affected by the problem: CityJet, which uses Fokker 50 aircraft, can be affected in a similar fashion on a weekly, or monthly basis. In all cases, passengers denied boarding must be compensated, either with a full refund or an alternative flight, plus financial compensation.

In Geneva I hear more noise complaints in Summer than in Winter from people living under the departure trajectories. This is particularly the case for people living North-East of the airport (Bellevue, Genthod, Versoix, Mies, Coppet, Terre Sainte etc.), especially as the hot weather, and the accompanying anticyclone, often give rise to consistent use of runway 05 (take-offs over Versoix).

The problem is also exacerbated by the fact that more people are wanting to be outside, rather than inside, their homes, especially in the light Summer evenings. A frequent complaint is that at peak times, there seems to be a non-stop constant stream of take-offs. Indeed, there can sometimes be more than 30 in an hour, eash making noise for over a minute.

Is the noise worse in Summer:probably. Can pilots do anything about it: maybe, but only if they would be given directives based upon a study of departure trajectories and the method of take-off (go full throttle in order to climb rapidly, or go fairly gently, in a line over the lake)? As far as I know, there has not been any recent study based upon the characteristics of modern jet aircraft.

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