I am happy to come back to the hon. Lady on the general point, but for example, deviation is common on emergency operations. The issue is broad, and I am happy to return to her on it.

On compliance with the regulations, all helicopter flights in the controlled air space over London are subject to an air traffic control clearance, and single-engine helicopters flying routes are subject to particular visibility minima. Air traffic controllers monitor compliance with air traffic control clearances and instructions, while the CAA, which is responsible for the enforcement of aviation legislation in the UK, will investigate any reported breaches and take enforcement action as necessary.

Police helicopter activity is governed by the provisions of the police operators certificate, which exempts the police from certain parts of the rules of the air regulations. Overall responsibility for policy on police helicopter operations lies with my right hon. Friend the Home Secretary. No legal action can be taken against pilots for noise disturbance, providing that they observe the rules of the air and fly in accordance with normal aviation practice.

The hon. Lady asked about complaints from the public, and referred to complaints by her constituents. The Department for Transport receives a number of complaints about the noise arising from helicopter operations, especially in the summer months. In responding, I can comment on the Government's overall policy, as I have just outlined, but we do not oversee day-to-day operations. Complaints are also received by the CAA. As the hon. Lady will know, however, there is no central complaints database. If the problem is a long-term one and the owner and/or operator of the helicopter is known, complainants may be referred to the British Helicopter Advisory Board, which has helpfully produced a number of documents. Those documents are available on its website, and they provide assistance to members of the community.

Complaints thought to be about police helicopters are matters for the relevant police air support or helicopter unit. One of the areas highlighted by the GLA environment committee, with which I have great sympathy, is that there could be a clearer complaints procedure for members of the public. The Department will work with interested parties to seek to deliver a more straightforward process. Local authorities can also play their part by helping their residents understand how to raise concerns. I intend us to work to help to alleviate the frustration experienced by the hon. Lady's constituents and others who have found it difficult to find the right route by which to complain.

Improved technology means that helicopters are less noisy than they were, and we seek reductions in noise at source by encouraging industry developments in aircraft and engine technology. The noise signature of helicopters does indeed differ from fixed-wing aircraft in that the noise derives not only from the engines but from the main and tail rotors, particularly from their tips. Therefore, silencing an engine alone will do little to improve the level of disturbance.

Since 1 August 1986, all new and modified versions of existing designs of helicopters to be flown in this country have been required to meet noise certification standards. The current requirements for helicopters are laid out in the Air Navigation (Noise Certification) Order 1990 and are based on the International Civil Aviation Organisation's annex 16. We in this country helped to establish, and have adopted, that international standard. However, where standards are concerned, further progress is dependent on international negotiation and agreement, which can then be implemented by the European Union and in national regulation. No significant technological advances are in prospect, but I assure the House that we will continue to seek reductions in source noise where possible, as we do for all aircraft. I should also say that most complaints that we receive relate to the unwanted presence of helicopters. It is rare for people to say that a slightly quieter helicopter would not bother them.

In December, I held a most constructive meeting with the Greater London assembly's environment committee. Its report made 14 recommendations, which I have studied, eight of which suggest action by the Department. However, committee members were realistic enough to recognise that it was important to identify key priorities, as I asked them to, so that our attention in the Department can be focused on the areas of most importance. One key priority that they identified was the need for a clearer complaints procedure. As I confirmed to the House, that is a point that we recognise and are taking forward.

The other key priority that we agreed was the need for better data. At present, it is true to say that there is little co-ordinated information collection, meaning that concerns about increased noise tend to be somewhat anecdotal. I assure the House that the Department will work with the CAA and National Air Traffic Services to collect more comprehensive data, liaising as appropriate with the environment committee's officers. It is right to proceed in that way. Instead of launching a flurry of activity to try to address a problem the detail of which is not clear enough, we should first establish an understanding of the actual position and the trends. That will enable us to inform decisions on next steps. It will not be straightforward to collect the further information, but we shall pursue it. I hope that the hon. Lady will agree that this represents a considered and sensible response to the points that she and the London assembly's environment committee have raised.

Question put and agreed to.

Adjourned accordingly at Eight o'clock.