About 2 1/2 hours before the Ukraine International Airlines jet with 176 people on board took off, the Federal Aviation Administration issued emergency orders prohibiting American pilots and airlines from flying over Iran, the Persian Gulf or the Gulf of Oman.
Goelz said airlines should have canceled all flights when Iran fired the missiles. Ukraine International Airlines flight 752 was No. 13.
By late Thursday, some major airlines had changed their thinking. Turkish Airlines temporarily halted flights to Iran and Iraq.
Some safety experts defended the airlines and said that if turns out the Ukrainian plane was shot down, even by accident, the blame rests entirely with Iran. “I don’t think you can fault the airline”, said John Cox, a former airline pilot and now a safety consultant. In 2014, aviation authorities issued warnings about Ukrainian airspace, telling airlines to fly above a certain altitude because of the fighting involving pro-Russia rebels armed with Russian-made surface-to-air missiles, who had already shot down government military planes.
Some airlines opted to fly around Ukraine completely, even though that meant longer flights and more fuel burn. Malaysia Airlines opted to keep flying over Ukraine, just at a higher altitude.
Collected and summarized from the source below by Minh Pham https://skift.com/2020/01/10/airlines-in-the-spotlight-over-iran-flight-strategy/