Operations at the Indira Gandhi International Airport were affected because of fog early on Friday.
Shallow to moderate fog formed over the airport between 3.30am and 8am with the lowest visibility recorded at 400-500m and Runway Visual Range at 500 metre on the third runway (29-11) during 6am to 8am.
“The cause is presence of high level of moisture — 85-95% —in the atmosphere because of overnight rain and stable lower level. The minimum temperature also dipped below 20 degree Celsius,” said RK Jenamani, director-in-charge, IGIA Met unit.
According to sources, some domestic carriers had problems in operating flights on time because of the unexpected dip in visibility.
The visibility reached CAT II Instrument Landing System at the runway 29-11 and some flights didn’t have pilots trained to fly in such conditions, sources said.
“The airport witnessed smog the day before yesterday but even moderate fog during end of April is highly unusual,” he said.
Jenamani said that even though instances of fog during March, when summer begins, is not highly unusual, there has never been fog during the fag end of April.