AS you might expect, ensuring aircraft can navigate and land safely in all weathers is an exact science.

Checking the ground systems that allow pilots to land their aircraft in poor visibility and adverse weather conditions is the job of an operation based at Teesside International Airport.

It's from there that Flight Precision Limited (FPL) calibrates blind landing systems for airports across the UK and Europe, ensuring that they are accurate to within six inches.

The company's techniques include using laser trackers that fire pulses from the ground to calibration equipment onboard one of its fleet of four aircraft.

The information is then simultaneously checked against data from satellite-based Global Positioning Systems and other equipment, to ensure accurate measurements.

Its services are also used to make checks when there has been an accident to rule out any chance of the crash having been caused by faulty equipment on the ground.

FPL is a UK-German joint venture between FR Aviation and Aerodata AG. Last month it celebrated ten years in business, during which it has carved out a major role as a world leader in the calibration of navigation equipment at both civil and military airports.

The company has 34 staff and four aircraft, including three B200 King Airs and one C441 Conquest, at its Teesside base, with back-up aircraft in Germany for use when required.

The most recent success for the company, which boasts an annual turnover of £6m, was the award of a five-year deal with Manchester Airport, to calibrate and check its guidance systems.

FPL's sales and marketing manager Andrew Radforth said: "The last ten years have been exciting ones for FPL. We now have four aircraft fitted with the latest and best measuring equipment that can be found anywhere in the world, and pride ourselves on being able to adapt to the needs of our clients.

"The expertise and knowledge that we have within the company is only something that can be built up in time as we deal with the flight calibration needs of our clients, from the most sophisticated European countries to those countries with more limited resources and budgets."

FPL became the UK's flight inspection service provider when it acquired the assets, staff and contracts of the Civil Aviation Authority's Flight Calibration Service (FCS) in October 1996.

The FCS had been supplying high-quality flight calibration services for a range of customers for 50 years. Until 1993 it was based at Stansted Airport as the Civil Aviation Flying Unit, before moving to Teesside in 1993 as FCS.

As a result, FPL's staff are all highly qualified, and include pilots, Navaid flight inspectors and radar flight inspectors.

FPL's customer list includes:

* NATS En-Route Ltd, covering regular flight inspection activities on UK en-route navigation and landing aids at Heathrow, Gatwick, Stansted, Edinburgh, Glasgow and Aberdeen Airports.

* All UK provincial and regional airports, including Manchester and Birmingham.

* The UK Civil Aviation Authority Safety Regulation Group for research.

* The Irish Aviation Authority for all navigation aids in Ireland.

* Belgocontrol, the civilian service provider in Belgium, as well as regular work in Germany, Spain, Portugal, Norway, Denmark, the Netherlands and Greece.

Alongside its civil operations, FPL also works for the military, having recently been awarded a ten year contract to provide flight inspection services to MoD flying establishments.

FPL has been providing such services to the MoD since 1996, including flight inspection services at MoD facilities in Germany, Cyprus, Gibraltar and the Falkland Islands.

It has also provided services at Banja Luka, Sarajevo and Pristina in Kosovo, following the end of hostilities, and has more recently been involved in Basra in Iraq, allowing aid to reach its people.

Military work is nothing new to Mr Radforth, 47, himself an ex military air traffic controller, with 25 years experience. He said: "I joined the air force at 17-and-a-half and served all over the world, including the Falkland Islands in 1982.

"I wanted to fly, but unfortunately my eyesight was too bad, so I became an air traffic controller instead.

"Air traffic controllers follow the same career path as other members of the RAF, and by the time I finished I was a squadron leader.

"Towards the end of my career in the air force I was in command of the air traffic control squadron at RAF Linton on Ouse, with 70 people under my control."

"While I miss the air force, my job with FPL gives me fresh and different challenges. In the future FPL is looking at gentle expansion into the rest of the world. The Middle East is another large potential area of operations for us, and from there we would like to target Africa.

"FPL has just celebrated its tenth anniversary, a decade which has seen dramatic growth and the building up of an enviable reputation for quality and value for money.

"With our large range of international blue-chip customers FPL is well poised for even greater success in the years ahead."