Aeroflot Flight 136

Aeroflot

Industry	Airline
Founded	1923
Headquarters	Moscow , Soviet Union
Area served	International
Products	Air transport services

Template:Infobox aircraft occurrence

Aeroflot Flight 136 was involved in a fatal aviation incident on Thursday, 28 October 1954, when an Ilyushin Il-12P operated by Aeroflot crashed on the slopes of Mount Sivukha in Krasnoyarsk Krai. This tragedy claimed the lives of all 19 individuals aboard, with some reports suggesting the death toll may have been 20.

Aircraft

Manufactured in 1949 at the Moscow-based aviation plant No. 30 "Znamya Truda," the Il-12P bore factory number 93013206 and serial number 32-06. Registered as CCCP-Л1789, it was allocated to the Main Directorate of Civil Air Fleet under the Council of Ministers of the USSR and assigned to the 64th (Vnukovo) aviation squadron within the Moscow territorial civil air fleet administration. At the time of the accident, the aircraft had accumulated a total flight time of 4,271 hours.

Crew

• Pilot in command: Pylaev Dmitry Ivanovich
• Instructor Pilot: Moskalenko Konstantin Grigoryevich
• Instructor Flight Mechanic: Ponomarenko Yuri Andreyevich
• Flight Mechanic: Likhobadin Ivan Ivanovich
• Flight Radio Operator: Ushakov Lev Nikolayevich
• Stewardess: Yukhalova Tatyana Sergeyevna

Crash

Nationality breakdown of those aboard

Country	Passengers	Crew	Total
Cyprus	4	0	4
China	1	0	1
Poland	4	0	4
USSR	4	6	10
Total	13	6	19

On 27 October, after arriving in Novosibirsk from Moscow, aircraft L1789 underwent a crew change. The newly assigned team was tasked with operating passenger flights numbered 135/136 between Novosibirsk and Irkutsk. These segments were part of an international connection linking with flights numbered 03/04 along the route Irkutsk—Ulaanbaatar—Beijing—Ulaanbaatar—Irkutsk, jointly operated by the Soviet-Chinese airline SKOGA (Sino-Soviet Joint Stock Company). Flight 135 departed Novosibirsk at 14:28 and safely reached Irkutsk by 18:52. The return trip, flight 136 to Novosibirsk, was initially planned but redirected to Krasnoyarsk due to unfavorable weather conditions at an altitude of approximately 2,700 meters. The crew was provided only with weather information relevant to the Krasnoyarsk route segment. Forecasts indicated variable stratocumulus clouds ranging from six to nine points and ragged rain clouds with a base between 600 and 1,000 meters. On the section between Taishet and Kansk, cloud bases were expected between 300 and 600 meters accompanied by medium to heavy precipitation, icing conditions within clouds, and mountain areas shrouded in clouds. Weather at Krasnoyarsk included variable upper stratocumulus clouds with lower limits from 600 to 1,000 meters, intermittent snow showers, northwest winds at speeds of six to nine meters per second with gusts up to twelve meters per second, and visibility ranging from four to ten kilometers. Wind speeds varied by altitude: at one thousand meters it was from 200° at forty kilometers per hour; at fifteen hundred meters from 240° at forty kilometers per hour; at two thousand meters from 250° at fifty kilometers per hour; and at three thousand meters from 260° reaching sixty kilometers per hour. At precisely 21:09, carrying thirteen passengers (including nine foreign nationals connecting from another flight and four Soviet citizens boarding in Irkutsk) along with six crew members, the Il-12 departed Irkutsk.

The aircraft passed over Nizhneudinsk at a ground speed of approximately two hundred seventy-five kilometers per hour around twenty-two fifty-five hours. Up to this point, it had maintained level flight above cloud cover without deviation. Subsequently, it entered cloud layers where light to moderate icing conditions were observed. The crew likely relied on outdated weather information received earlier in Irkutsk that indicated a southwesterly wind blowing at forty kilometers per hour. However, by twenty-three fifty hours, meteorological data received by Krasnoyarsk's Aviation Meteorological Systems (AMS) revealed that winds were actually coming from the northwest with velocities reaching one hundred thirty kilometers per hour at two thousand meters altitude. This meant that instead of drifting northward as anticipated, the aircraft was being pushed southward. Unfortunately, this critical update was neither relayed to Krasnoyarsk’s flight supervisor nor communicated to the crew onboard.

At twenty-three twenty-six hours, navigation bearings were obtained showing a back bearing of two hundred eighty-two degrees from Krasnoyarsk-Severny Airport and a true bearing of one hundred forty-seven degrees from Yeniseysk Airport. These readings indicated that since passing Nizhneudinsk thirty-one minutes earlier—covering one hundred thirty-two kilometers—the plane had drifted eighteen to twenty kilometers south off its intended course. At twenty-three forty-three hours, despite reporting passage over Kansk, this claim was unreliable because the radio beacon at Kansk airport had been deactivated due to delays by senior dispatchers in Krasnoyarsk’s area control service. Later at twenty-three fifty-four hours, new bearings communicated to the crew included an approximate back bearing near two hundred eighty degrees from Krasnoyarsk airport and a true bearing of one hundred fifty-eight degrees from Yeniseysk airport. These figures placed the aircraft seventy-three kilometers away from Krasnoyarsk; combined with previous data suggested an improbable ground speed of four hundred thirty-five kilometers per hour. Consequently, it became evident that crew position reports for Taishet and Kansk were based solely on estimations rather than actual navigation confirmation. The "approximate" back bearing provided contained inaccuracies acknowledged by the radio operator who reported them back to ground control. This mistake arose because trainees operated radio direction finders in Krasnoyarsk while experienced staff members were absent due to military service obligations.

Ground controllers failed to reconcile discrepancies between reported ground speeds and bearing data; they neither pinpointed the exact location of the aircraft nor issued corrective instructions. Both flight supervisors and senior dispatchers neglected essential calculations and oversight responsibilities during this phase. Following twenty-three twenty-six hours, neither crew members nor air traffic control personnel possessed accurate knowledge of L1789’s position. Previous flights on similar routes had also deviated southward without causing alarm despite resulting delays.

Although regulations mandated entry into Krasnoyarsk airspace at two thousand one hundred meters altitude, controllers instructed flight 136’s descent to fifteen hundred meters instead. Confident that their ground speed remained at two hundred seventy-five kilometers per hour, the crew opted to proceed toward Novosibirsk according to schedule. They contacted Novosibirsk for updated weather information receiving confirmation that overcast conditions prevailed with a cloud base near two hundred ninety meters visibility extending ten kilometers alongside southwest winds at five meters per second.

Between midnight zero-two and zero-four hours, communications reported approaching Krasnoyarsk at an altitude of two thousand seven hundred meters carrying sufficient fuel reserves totaling approximately two thousand six hundred liters; intentions were expressed to overfly Novosibirsk pending acceptance there. However, air traffic control informed them that Novosibirsk airport was closed due to weather conditions and instructed immediate landing in Krasnoyarsk instead.

The crew acknowledged these directives and commenced descent toward fifteen hundred meters altitude as previously advised. At zero-zero-ten hours local time (04:10 Krasnoyarsk time), attempts by Krasnoyarsk airport controllers to establish contact with L1789 went unanswered despite repeated calls. Following these unsuccessful communication efforts, search operations were initiated but no trace of the aircraft could be found.

In June nineteen fifty-five—seven months after disappearance—a hunter discovered wreckage on Mount Sivukha (elevation one thousand eight hundred seven meters; 54°30′25″N 94°41′10″E) near upper reaches of the Mana River. An investigative team arrived on site on twelve June confirming that while flying along a magnetic heading of two hundred eighty degrees at an altitude near one thousand seven hundred twenty-five meters—approximately one hundred thirty-two kilometers south off course and two hundred four kilometers distant from Krasnoyarsk airport—the airliner collided with steep rocky eastern slopes of Mount Sivukha at an angle between forty and forty-five degrees resulting in total destruction.

All nineteen occupants lost their lives including members of a Polish United Nations delegation returning from Vietnam. Official records cite nineteen fatalities; however alternative sources suggest twenty deaths due to omission of co-pilot details in official crew listings.

Causes

The investigative commission identified several key factors contributing to the accident:

1. Severe negligence by Krasnoyarsk air traffic controllers, including the airport flight supervisor and the senior dispatcher responsible for area control. They failed to properly manage the flight, directing the crew to descend to 1,500 meters rather than the prescribed 2,100 meters, and neglected to activate the radio beacon at Kansk airport. As a result, the aircraft veered off its intended path and entered mountainous terrain exceeding 1,500 meters in elevation.
2. Duty meteorologists at the AMS stations in Irkutsk and Krasnoyarsk issued inaccurate wind forecasts for higher altitudes. Additionally, the Krasnoyarsk meteorologist on duty did not communicate updated wind direction and speed information received at 23:50 to either the flight supervisor or the flight crews.
3. The Krasnoyarsk territorial civil air fleet administration inadequately supervised Krasnoyarsk airport services, failing to rectify shortcomings within airport operations, particularly in air traffic control.
4. Substandard performance by the Krasnoyarsk radio direction finder unit further compromised navigation.
5. The flight crew miscalculated wind velocity and direction, resulting in a 10° southern deviation. Because the actual wind originated from the northwest rather than southwest, this adjustment increased the aircraft’s drift toward the south of its planned route.

Aftermath

Although foreign nationals perished in the crash, all related information was kept confidential. In summer 2010, a team of ten individuals traveled to Mount Sivukha using GAZ off-road vehicles and erected a memorial cross at the site of the accident. Later, during summer 2013, a commemorative plaque was placed at the crash location as well.

Links

• "Манское белогорье" [Manskoye Belogorye]. Vimeo (in русский). Retrieved 2015-01-06.