A blanket of thick fog over national capital New Delhi and its adjoining regions paralysed air traffic in the morning hours of Friday, forcing cancellations of two Ranchi-bound flights and delaying two more.

The fog — a usual phenomenon in northern India at this time of the year — grounded Jet Airways’ Delhi-Ranchi flight, which reaches the state capital around 1.25pm. Later, a Kingfisher flight, which was scheduled to land in Ranchi at 2.30pm, was also cancelled.

The morning fog also induced several delays in departure with Air India’s Delhi-Ranchi flight landing in the state capital more than seven and a half hours behind schedule at 3pm. Likewise, an Air India afternoon flight, which was supposed to touch down at 2.50pm, had to be rescheduled due to the inclement weather. It finally reached Ranchi at 7.00pm.

According to an airline official, the visibility at Indira Gandhi International Airport dropped to less than 50m in the morning against the minimum requirement of 150m.

The misty conditions also threw train timetables out of gear with several long-distance trains from Delhi running behind schedule.

While the Jammu Tawi Express chugged into Ranchi at 1.40pm, a good four-hour delay, Jharkhand Swarna Jayanti Express arrived around 8pm instead of 4pm. Patliputra Express, which was scheduled to arrive at 4.40am, was running nine hours late. Vananchal Express, which connects Ranchi with Bhagalpur, arrived one hour behind its scheduled time of 6.40am.

“A number of trains have been delayed because of reduced visibility levels on the tracks,” said senior divisional commercial manager, Ranchi, K.S. Mukherjee.

Experts, however, said the conditions would improve on the last day of the year.

“It might be slightly overcast, but the weather will be pleasant as we welcome 2012,” said A. Wadood, chairman of Birsa Agriculture University’s Agro Physics and Meteorology department.