National capital New Delhi woke up to a foggy morning on Tuesday, delaying air traffic for the first time this winter.

Though air traffic was normal before 0600 hours, a number of flights were delayed as the visibility decreased to 50 metres low due to a thick blanket of fog. The runway visibility was below 100 meters between 6am and 9am in the morning, airport sources said, adding that all flights took off on time before 6am in the morning but delays started in as the day set in.

Around a dozen flights were delayed and one Delhi-Amritsar Air Deccan flight was cancelled due to the foggy condition.

An Indian Airlines to Bangalore took off using CAT III-A instrument landing system, while a Hyderabad-Delhi flight of the domestic carrier landed using the CAT III-B equipment, which can operate in near-zero visibility conditions.

Only one runway was operated during the period, airport sources said. The flight to Bangalore was, however, delayed because of three private airlines aircraft without the landing capability system blocking the runway.

"Only flights with the CAT III facility can take off under such condition," said airport sources, adding, "CAT III system was activated and only a few international flights could land. However situation improved steadily after 9am."      

Delhi recorded a minimum temperature of 8.7 degrees Celsius, one degree above the normal. Night temperatures are expected to plummet further in the next few days.