THE service responsible for providing air support to Dorset Police say they are making changes after the authors of an independent report called for it to be overhauled.

Bosses at the National Police Air Service (NPAS) spoke after it was revealed that police helicopters take so long to get to crime scenes that thousands are called off mid-air because the incident has already finished, a watchdog has found.

Nationally, more than 40 per cent of call-outs last year were cancelled because the incident was over before air support had arrived, according to an independent probe.

In many areas it took more than half-an-hour for a helicopter to reach the scene. In Dorset, the average time is 22 minutes and 55 seconds - the eighth fastest response in England and Wales.

The Met Police can expect a helicopter in 10 minutes and 37 seconds. Officers in Cumbria wait 66 minutes and 33 seconds.

A report by Her Majesty's Inspectorate of Constabulary and Fire and Rescue Services has called for urgent reform.

HM Inspector of Constabulary Matt Parr, who led the inspection, said: "Savings have primarily been made by cutting the service provided to forces rather than increasing efficiency.

"An inconsistent service means that many incidents requiring air support are over before a before helicopter can arrive."

He also said there were "high levels of skill, dedication and commitment" among staff but "fundamental problems" with how the service was structured.

Long response times have contributed to a decline in forces using air support, especially in police chases, the report found.

Forces in England and Wales were responsible for their own air support until a national collaboration was created in 2009.

The report says the service "in its current form is financially unsustainable" and added: "It would be difficult to conclude that NPAS has a sustainable future in its current form."

Chief Constable Dee Collins, air operations certificate holder for NPAS said: "The journey to having a national police air service has been challenging for NPAS and we have learnt a lot along the way.

"To deliver stretching national efficiencies, we have sought to change the expectations of police forces about the role of air support in policing and to do so has been a difficult process."

Mark Burns-Williamson, chairman of NPAS and West Yorkshire Police and Crime Commissioner said: "Many of the areas identified in the report are already recognised and there is ongoing work to address them but I think it is important to state that NPAS has successfully delivered phase one of the first national collaboration of this kind which is now a totally borderless 24-hour police aviation service and now delivers on previous and current government commitments to create a NPAS."

Chief Constable Alec Wood, chairman of the NPCC Operations Co-ordination Committee said the findings would be used "to shape a new strategy for police air support that will resolve the issues with our current provision and take advantage of new technology".

"We have already started to progress some of the recommendations and have recently surveyed all forces to help inform our plans," he added.