New Delhi, Dec. 14: The Centre plans to make it mandatory for airlines to train their pilots in the Category II landing system, which allows planes to land in poor visibility.

The announcement by civil aviation minister Praful Patel came after fog in Delhi disrupted countrywide flight schedules for three days running.

The directorate-general of civil aviation (DGCA) plans to amend aviation rules to make such training mandatory, Patel told the Lok Sabha. “While we want to reduce fog-related inconvenience caused to passengers, we cannot ignore safety at any cost,” he said.

The minister said the government plans to upgrade four or five airports in the northern region, which is generally affected by fog during winter, to Category II level. These will include airports in Amritsar, Lucknow and Jaipur.

If intense fog in Delhi pegs visibility down to almost zero, these airports will be used as secondary landing stations for both domestic and international flights.

Category II allows landing if runway visibility is not less than 350 metres. Delhi airport is the only one in India with the Category III B system, which allows landing even if runway visibility is a mere 50 metres. But most flights were held up in the past few mornings because pilots do not know how to use the system.

Airport officials said if pilots were trained in Category II, they could easily negotiate Delhi landings on most winter mornings as visibility rarely, if ever, falls below 350 metres.

Patel said Category II and Category III training required pilots to fulfil certain conditions: they must have flown at least 2,000 hours — 500 hours in particular types of high-technology aircraft — and done a minimum number of take-offs and landings.

Officials said the number of pilots trained in Category III had risen from 148 two years ago to 326, and the number of Category II compliant pilots gone up from 661 in 2005 to 794 in December 2006.