On Feb 20th 2018 The Aviation Herald received verified information, that the flight had been enroute at FL210. At 05:52Z the aircraft was cleared to descend from FL210 to FL170 while tracking airway W144. At 05:53Z the aircraft was cleared to join the NDB instrument approach procedure overhead the NDB Yasuj, the crew reported 25nm from the aerodrome at 05:55Z and at 05:59z 14nm from the aerodrome. At 06:00Z the crew correctly read back QNH 1021 reported by ATC, this was the last communication from the aircraft. When tower called the aircraft at 06:04Z there was no reply anymore.