The last message from flight L3904 came at 16:14, somewhere in the mountains southeast of Khabarovsk. 'Altitude 1,000 meters, ground not visible, flying in clouds, seeing nothing.' One minute later, the Il-12 entered a nearly vertical descent and hit a mountainside at 850 meters elevation. All 28 people aboard died — four crew members and 24 passengers, including three children. The investigation that followed uncovered not a single catastrophic failure but a chain of smaller ones, each giving the next a handhold: a weather forecast off by a factor of three, a direction finder that had been broken for three weeks but whose operators kept sending approximate bearings anyway, a dispatcher who received vital position information and never passed it on. The crew of CCCP-Л3904 flew a competent aircraft into the ground because virtually every system designed to prevent that outcome had already quietly failed.
The Il-12P had logged 7,834 hours of flight time when it set out from Magadan on September 19, 1958, bound for Khabarovsk via Okhotsk and Nikolayevsk-on-Amur. Before departure from Okhotsk, the airport navigator never verified the crew's flight calculations, and the flight plan was never formally approved. The dispatcher authorized the departure anyway. The weather forecast given to Captain Pyotr Konoplev predicted a west wind of five to eight meters per second along the route. The actual wind was north-northwest at up to nineteen meters per second — a difference that would push the aircraft steadily off course throughout the flight. Konoplev, trying to compensate for what he believed was a westerly drift, corrected into the headwind direction, driving the plane further and further from the route. By the time the crew passed Nikolayevsk, they were 24 kilometers west of the airport — outside the reduced range of the navigation beacons in the snowstorm, and unable to establish radio contact with the ground.
As fuel burned down and the crew grew desperate for bearings, they reached the short-wave direction finder at Khabarovsk airport. It had been out of service since August 27 — three weeks before the crash — undergoing maintenance. Operators had been instructed not to provide bearings or transmit them to aircraft. But they did anyway, sending approximations that the crew trusted. When the crew received a bearing of approximately 312 degrees, the direction-finder operator relayed it to another sector of ground control, which reported back that no aircraft was operating in that area. The bearing was never passed to the dispatchers or the flight operations manager. Meanwhile, air defense radar tracked an unidentified aircraft near Yedinka — potentially CCCP-Л3904, far from where the dispatchers believed it to be. An air defense officer called the control center to report it. A voice answered that no aircraft were in that area. The investigation later concluded that voice probably belonged to a district service operator, who denied it.
Between 14:16 and 15:19 — more than an hour — the Il-12 effectively circled in one area while its crew tried and failed to determine where they were. The aircraft's compass had failed. The radio compasses were erratic in the snowstorm. The NDB navigation beacons had reduced range. Ground controllers tracking the plane's reported positions assumed it was flying a straight course toward Khabarovsk, when it had in fact overflown the city and was wandering to the south and east. At 14:43, with 800 liters of fuel remaining, the crew reported their position. At 15:00, only 600 liters remained. The dispatcher instructed them to proceed in fuel-efficient mode. There was a backup airfield at Yedinka that had a functioning ground radar transponder — but neither the flight operations manager nor the controllers knew it was there. The Yedinka airfield dispatcher heard the entire radio exchange and said nothing.
With 210 liters remaining — perhaps twenty minutes of fuel — the crew began descending through clouds over mountainous terrain, searching for any visible ground to land on. The district service dispatcher, not knowing their actual position, instructed: 'Do not land until fuel is exhausted.' At 16:11, the crew reported flying at 1,500 meters with the ground barely visible. A minute later, at 1,200 meters, they were beginning to search for a landing site. The final transmission came three minutes after that. The aircraft came down on the slope of a 1,050-meter mountain in Lazo District, 145 kilometers southeast of Khabarovsk. It was found at 850 meters elevation. The investigation's conclusion was measured but damning: the dispatching service did not manage or control the flights; navigation infrastructure was allowed to degrade without informing aircrews; position information was received and discarded; and the system as a whole treated the disappearance of an aircraft with bureaucratic equanimity until there was no aircraft left to find.
The crash site lies at approximately 47.57°N, 136.42°E in the mountainous Lazo District of Khabarovsk Krai, 145 km southeast of Khabarovsk (UHHH). The terrain rises sharply here; ridgelines reach 1,000–1,200 meters. The Khabarovsk Novy Airport (UHHH) lies to the northwest. Flying the approximate route of the doomed flight — Okhotsk to Khabarovsk — the mountainous character of the terrain between the Amur lowlands and the Sea of Japan coast is immediately apparent.