Controllers at Delhi airport had been refusing to use the state-of-the-art equipment for more than six months, citing safety reasons.

They have now decided to use the new system, in part because of the huge disruption in flight schedules in recent weeks caused by heavy winter fog.

The new technology should enable Delhi airport to function in all but the most extreme conditions.

Pilots are welcoming the decision but say they are still concerned about the state of air-traffic control over the rest of India.

They say many more steps need to be taken just to achieve minimum safety standards.

1996 collision

349 died in the collision

The new system was purchased shortly after a mid-air collision in 1996 when 349 people died in a collision between a Saudi Airlines Boeing 747 and a cargo plane from Kazakhstan.

The crash was blamed in part upon an antiquated air-traffic management technology.

However, controllers refused to use the new equipment because they said it did not permit proper monitoring of radio conversation with aircraft.

Aviation Ministry officials said the controllers were more concerned that the system was able to assess blame for near-misses, which pilots say happen too frequently over India.

The controllers are represented by a strong trade union that has more than once shut down an airport to protest against disciplinary action in response to near-misses or failures to maintain safety standards.

The union says controllers do their best and should not be blamed for antiquated systems or technological lapses.