New Delhi: Airports in Jaipur and Lucknow have been upgraded to allow planes to land in low-visibility conditions, potentially reducing pressure on the Delhi airport where the winter fog tends to disrupt flights.

Upgraded instrument landing systems at the two airports will become operational at 5.30am on Thursday, said an official with the Airports Authority of India (AAI) requesting anonymity.

The so-called CAT-IIIB facility in India has so far been available only at Delhi airport. The technology helps flights land when visibility is as low as 75 meters.

All flights flying into Delhi and northern airports typically carry extra fuel during the winter, when fog leads to disruptions across north India, said an airline pilot who did not want to be named. The flight typically carries enough fuel to travel to two alternative airports and  for diversion to Ahmedabad.

The upgraded systems Jaipur and Lucknow means a flight on its way to Delhi can be diverted to Jaipur or Lucknow in case of dense fog in the capital. Delhi airport, meanwhile, can clear the backlog of flights faster as the number of flights landing in Delhi get reduced.