They resumed their operations before dawn Monday and have now outlined the search for the ill-fated plane which authorities say crashed and killed 66 people on board, Fars news agency said.
A relative improvement in weather conditions allowed helicopters and drones to fly over the extremely mountainous area which features some 100 peaks higher than 4,000 meters (13,000 feet). However, blizzard conditions are forecast to return around noon, the agency said.
The Aseman Airlines ATR-72 plane, a twin-engine turboprop used for short-haul regional flight, was traveling from the capital Tehran to the southwestern city of Yasuj. It is believed to have crashed into Mount Dena in the Zagros mountain range, some 390 miles south of the capital.
The plane disappeared from radar screens 50 minutes after taking off from Mehrabad airport which mainly handles domestic flights.
Air controllers say the pilot had not reported any problems in his last contact with the tower 14 miles from the airport. According to airplane-tracking website FlightRadar24, the plane’s last signal at 0555 GMT showed it at 16,975 feet and descending.
Emergency workers have had to get to the remote area by land amid dense fog, high winds and heavy snow which have hampered search and rescue operations.
As many as 26 teams of mountain climbers were scouring valleys, slopes and ridges on Monday in the hope of finding the debris.
“The visibility in the defined search area is not very good and there is turbulence, so safety concerns must be taken into account,” Morteza Dehghan of the Civil Aviation Organization told state television.