Early on Jan. 8, a Ukraine International Airlines passenger plane took off from Imam Khomeini International Airport in Tehran. It was supposed to be a routine flight between the Iranian capital and Kyiv’s Boryspil International Airport, a transit destination for most of the plane’s passengers.

The Boeing 737–800 jet airliner departed at 6:12 a. m. Kyiv time. It gained about 2,400 meters in altitude. Then, at 6:14, it sent its last signal, according to the FlightRadar24 plane tracking website.