A spokesperson for the STSB said that the Junkers "fell like a stone to the ground", and that the heatwave in Europe could have been a factor in the crash, as heat reduces an aircraft's climb performance. The police indicated that no distress signal was received from the aircraft prior to the crash. Investigators ruled out a collision with a cable or another aircraft, and said that there was no indication of foul play or the aircraft losing parts before the crash. The aircraft was not fitted with any flight recorders, as they were not required due to the age of the aircraft. Investigators are hoping to find some relevant information from passengers' personal photographic and video recordings during the sightseeing flight. The STSB issued its preliminary report on 15 August 2018. An intermediate report was issued on 20 November 2018, citing anterior corrosion marks and cracks, not related to the accident, which effectively grounded the two remaining Ju-52 of Ju-Air (HB-HOP and HB-HOS) until further investigation of these airframe and engine issues.