A PROMINENT figure at one of Hampshire's biggest employers quit his high-profile job following internal disagreements over a £1 billion modernisation programme, it emerged today.

Dr Rob Witty stepped down from his role as technology supremo at National Air Traffic Services (NATS) after differences of opinion with chief executive Paul Barron.

A spokesman for NATS, which employs more than 2,200 people at Swanwick and Whiteley, confirmed a "disagreement" between both men led to Dr Witty leaving.

The departure is significant because NATS, which provides air traffic control services to aircraft in UK airspace, is embarking on an ambitious new chapter in its chequered history.

NATS, which handles two million flights with 180 million passengers, is rolling out a £1bn investment programme so it can deal with three million flights by 2010.

Dr Witty, a renowned expert in safety critical software engineering, took over the reins as chief technology and programmes officer in 2002.

He replaced Frank Agnew - the IT wizard who won the respect of the computer industry in the face of well-publicised adversity.

Mr Agnew helped NATS keep its reputation intact when the arrival of the £337m air traffic control system for purpose-built Swanwick was repeatedly dogged by lengthy delays and technical glitches.

Swanwick finally went live operationally in January 2002.

It is not known yet what Dr Witty's next step is following his departure.

Rick Brett, branch chairman of the Air Traffic Specialists' professional union Prospect, said: "We are understandably disappointed at this news. Dr Witty has always impressed us with his realism and strong commitment to the advancement of engineering within NATS."

Dr Witty's role is now split between Nigel Horne, an independent technology expert who has advised NATS on a number of major engineering projects, and Ian Mills, director of business improvement.

Announcing the changes, Mr Barron said: "The success of our company is inextricably linked to our ambitious

£1 billion modernisation plan and the 350 engineering projects that support it.

"We will be moving swiftly to find the right capability for this task and I have every confidence in the ability of Nigel and Ian to manage this effectively in the interim."

The government owns just over half of NATS, with a consortium of airlines and employees owning the rest.