Unreasonably high risk was taken by the pilots of the crashed L-39 aircraft at Graff Ignatievo airbase

Unreasonably high risk was taken by the pilots in the air accident at Graf Ignatyevo base on 13 September, in which two military personnel died. This is the conclusion of the Defence Ministry commission set up to investigate the accident.

Lieutenant Colonel Petko Dimitrov and Captain Ventsislav Dunkin died during a training flight with an L-39 combat trainer aircraft, part of an air show at the air base on the occasion of the 20th anniversary of Bulgaria's accession to NATO.

"With the creation of a stall overload to curve the trajectory parallel to the runway, the speed decreases and is insufficient according to the methodical scheme to enter the next vertical figure. The Board considers that at this point, complicated flight conditions have arisen. At 12 hours 30 minutes and 1 second, the crew entered the climb for an initial vertical figure with an overshoot of 3,6 G in a right bank of 6 degrees, the altitude at that point was 68 metres and the speed 455 km/h. The Board considers that the introduction of the plane into a vertical figure with these flight parameters has exacerbated a complex situation. At 12 hours 30 minutes and 13 seconds after reaching an altitude of 647,61 metres at a speed of 213 km/h, the crew started a descending movement with a pitch angle of minus 39,68 degrees, which increased in the following second to minus 51,11 degrees. At this point the situation had deepened into an emergency. Between 12 hours 30 minutes and 16 seconds and 12 hours 30 minutes and 17 seconds, i.e. in just one and a half seconds, the conditions for a successful ejection were met. Since the crew did not take any action for an emergency departure of the aircraft, the Board considers that at 12 hours 30 minutes and 17 seconds the situation had progressed to catastrophic. From all this, the Board classified the aviation accident as a crash. The proximate cause was the aircraft's apparent encounter with the ground. As the main cause, the Board considers unreasonably high risk-taking in the execution of elements of complex aerobatics. As concomitant causes were identified violation of safety measures, violation of the order of execution of the flight task and improper assessment of the altitude reserve when deciding on the method of removal of the aircraft from the figure in the vertical plane, since at the upper point the aircraft was controllable and could have been removed from the figure in another way," explained Petko Vassilev - a state expert in the department "Investigation of aviation accidents and incidents" in the Military Police Service.

"We cannot afford to lose human lives in peacetime," caretaker Minister Atanas Zapryanov was adamant.

Defence Minister: All data from the black box of the crashed L-39 aircraft was retrieved

However, he explained that he would take personnel decisions only after all the information on the case becomes clear.

"Be sure that those who do not serve according to the rules and regulations and cannot carry the burden of service will not continue to hold these positions of responsibility. Once all the information becomes clear, then personnel decisions will be made. I will not comment on hearsay hypotheticals," Zapryanov said.

Images by BTA

"For me as the Minister of Defence this incident is extremely serious, human lives are the most precious for the Ministry of Defence. The commission's investigation is independent of the judicial and pre-trial investigation. Establishing the extent of anyone's culpability and responsibility is not the subject of the inquiry. We cannot afford to lose lives in peacetime. Moreover, in wartime, commanders ask themselves this question every day - why are we losing lives in battle?" the minister noted.

"Transparent and accurate expertise can answer about the cause of the incident," Zapryanov said.

Such incidents should be kept to a minimum, the minister insisted.

"Many times you ask me about resignations and you have the right to ask this question, because everyone should be responsible for their actions, but the MoD is neither a court nor a public prosecutor's office and we do not impute blame nor point out culprits," Zapryanov stressed.

In the report of a commission to investigate the air accident, work was done in four areas, explained Colonel Petko Vassilev - a state expert in the department "Investigation of aviation accidents and incidents" in the Military Police.

"First - a study of the flight training of the crew and the organisation of the flight, second - a medical examination, third - a study of the aviation equipment and fourth - a study of the circumstances under which the accident occurred. On September 9, 2024 a general preliminary training was conducted by video-conferencing, and a briefing was prepared on the knowledge of safety measures for the organization and conduct of the Open Flying Day at the Graf Ignatyevo airbase," Colonel Vassilev said.

"Was there ammunition? Yes. There was, because each flight is performed with the specified configuration, so it is necessary to load the aircraft, including the ammunition, so that the centre of gravity does not change and hence the behaviour of the aircraft, especially during aerobatics," said Lieutenant General Tanko Stoykov.

After the accident it became clear that the investigators are working on 3 main hypotheses - pilot error, technical problem or incorrect command. It showed that the machine was flying too low.

***

An L-39ZA aircraft crashed during a training flight on September 13, 2024, at the Air Base near Graf Ignatievo,. As a result, the two pilots from the 12th Air Base in Dolna Mitropolia, Petko Dimitrov and Ventsislav Dunkin, died.

By order of caretaker Defence Minister, Atanas Zapryanov, on September 18 they were posthumously promoted in rank.

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