ACCIDENT data recorders, designed to yield information about what happens to a racing car during and immediately before an accident, will be fitted to all Formula One cars from the first race of the new world championship season in Melbourne on March 9th.

In a week when the sport has been dominated by the anticipation of Frank Williams's trial for manslaughter over the death of Ayrton Senna, which opens tomorrow, the adoption of these recorders is regarded as a crucial first step in providing car makers and the sport's governing body (FIA) with an accurate understanding of what really happens in motor racing accidents.

"The implications for safety are very encouraging," said Max Mosley, the FIA president. However, whether these accident recorders might have been able to shed anymore light on why Senna's Williams-Renault crashed at 190 m.p.h. during the 1994 San Marino Grand Prix at Imola is another matter altogether.

"There would certainly have been some additional data gathered," said Harvey Postlethwaite, technical director of the Tyrrell Formula One team, "but that does not necessarily mean you would be able to tell what caused the accident. Gathering the data is one thing, but interpreting it can be something of a minefield.

"But it is a laudable first step towards gathering accident data from across the whole spectrum of motor sport. But like any first step, there are obviously going to be some teething troubles."

The accident data recorders will be mounted beneath the fuel tanks of the grand prix cars, just behind the driver's seat. They will receive data from external sensors enabling them to monitor the speed at which the wheels are rotating how the driver is operating the throttle and the angle at which he is holding the steering wheel at the moment a car goes out of control.

Within the unit are sensors, accelerometers and gyros which track the motion of a vehicle during the accident and can indicate the force at which a car hits a barrier.

The recorders operate in two logging modes. In normal mode it records data from sensors at various races, replacing old data once its memory is full. But if the recorder determines that an accident is occurring - which it does when it detects forces in excess of the baseline "threshold values" programmed into the system - it switches to accident logging mode and protects all information previously stored.

Jacques Villeneuve broke the Estoril lap record after a thrilling battle with the Benetton pair of Gerhard Berger and Jean Alesi in pre-season testing yesterday.

The Canadian, favourite for this year's Formula One world championship, clocked one minute 18.36 seconds in his Williams.