the flight, 32 kilometers north-west of Kutaisi airport and 7 kilometers north of Gegechkori, crashed into the mountainside at 900 meters. The aircraft was completely destroyed and caught fire. All 32 people on board were killed. The total on board should have been 5 crew members and 24 passengers. But while studying the wreckage, three stowaway passengers were also found. Cause According to the weather forecast, a thunderstorm was expected on the main flight route, with stratocumulus and cumulonimbus clouds having a lower limit of 600–1000 meters and a horizontal visibility of 4–10 kilometers. The pilot knew that there was a thunderstorm on the main route from Kutaisi to Sukhumi, while on the roundabout (via Poti) weather conditions were good. A flight that left Kutaisi earlier determined that the main route to Sukhumi was impossible, therefore, requested permission to follow the detour route. However, the crew of Flight 663 did not receive this information before departure. This was probably caused by the fatigue of the pilot, who, at the request of the deputy chief of the airport, was delayed from the night shift and had been working for around 14 hours. At 10:38, the control tower was informed that cloud cover had dropped from 1100 to 450 meters, however, this information was not communicated to the crew of Flight 663 either. When the crew tried to circumvent the thunderstorm in the conditions of limited visibility, they did not notice that they were right on the mountains. The lack of visibility and communication resulted in the aircraft colliding with the mountain. According to the commission, the cause factors were: The air traffic controllers allowed a visual flight at an altitude of 1500 meters in a mountainous area without meteorological conditions. The air traffic controllers at Kutaisi airport did not prohibit the departure and did not warn the crew about the clouds, instead giving instructions to fly at an altitude of 1500 meters, an altitude dangerous during the weather conditions. The pilot performed a visual flight, although in these weather conditions it was impossible, while below the safe altitude. The deputy head of Kutaisi airport allowed the PM of the day shift to be two hours late for work, but when the day shift entered, he did not personally replace him, and therefore the RP of the night shift was forced to stay at work. In turn, the request for an RP