A deal with world powers on Iran's nuclear program has lifted some of those sanctions, opening the way for Iranian airlines to update their creaking fleets. However, US President Donald Trump's refusal to recertify the deal has injected uncertainty into those sales.
The crashed ATR-72 aircraft belonging to Iran Aseman Airlines took off from the capital Tehran on Monday morning and disappeared from the radar screen 50 minutes after its departure, near an area about 22.5 km from its destination Yasuj, an industrial city in the Zagros mountains in southwestern Iran.
Official reports confirmed that all 66 on board were killed in the air crash. There were 59 passengers and six crew members on the flight, the news agency said.
Singapore President Halimah Yacob has written to Iranian President Hassan Rouhani to convey her condolences on the crash, according to a statement on Tuesday from the Ministry of Foreign Affairs.
Mount Dena, is about 14,435 feet tall.
It gave its last signal at 0555 GMT when the flight was at 16,975 feet and descending, according to FlightRadar24. The airport itself is at almost 6,000 feet.
"Regardless of the weather condition, search and rescue operation will go on", Shahin Fathi, operation deputy of Iran's Red Crescent Organization told the News Channel.
Press TV said search teams reached the crash site before dawn on Monday.
Iran Rescue Teams 'Find Crash Site'
Aseman Airlines, owned by Iran's civil service pension foundation, is a semi-private air carrier headquartered in Tehran that specializes in flights to remote airfields across the country. It flies both nationally and internationally.
Aseman Airlines posted an image of the plane involved in the crash on its Instagram account. However, it is banned from flying in the European Union over safety concerns.
The plane was travelling from Tehran to the southern city of Yasuj in Isfahan province when it came down in the Zagros mountains.
The post did not provide any insight as to what led to the grounding of the aircraft.
The twin-engined turboprop ATR 72 was just over 24 years old.
Aseman Airlines has faced various fatal accidents with their planes.
It was originally reported that 66 people died, but that figure was later revised. 74 people lost their lives.
With decades of global sanctions pending the commercial passenger aircraft fleet of Iran seems to have aged with air accidents becoming quite a regular in the last few years.
Turkey warns Syria troops it will fight in Afrin
The Observatory said Monday's shelling by Turkish troops killed three people, including a child, and that others were wounded. In the speech to members of his ruling AK Party, Erdogan also promised that a siege of Afrin would begin soon.