After over 40 years of secrecy, the real cause of death of Soviet cosmonaut Yury Gagarin, the first human in space, has been made public. Prominent Russian cosmonaut Aleksey Leonov reveals the truth behind the events of that tragic day.

For over 20 years Aleksey Leonov, the first man to conduct a spacewalk in 1965, has been struggling to gain permission to disclose details of what happened to the legendary Yury Gagarin in March 1968.

Back then a State Commission established to investigate the accident (which Leonov was a part of), concluded that a crew of MiG-15UTI, Yury Gagarin and experienced instructor Vladimir Seryogin, tried to avoid a foreign object – like geese or a hot air balloon – by carrying out a maneuver that had led to a tailspin and, finally, collision with the ground. Both pilots died in that test flight.

“That conclusion is believable to a civilian – not to a professional,” Leonov told RT. He has always had a firm stance against the secrecy surrounding Gagarin’s death, and wanted at least his family to know the truth.

"In fact, everything went down differently,” he says.

According to a declassified report, there is a human factor behind the tragic incident - an unauthorized SU-15 fighter jet was flying dangerously close to Gagarin’s aircraft.

Leonov had been in charge of parachute jump training on that day. The weather was extremely bad, with rain, wind and snow making it impossible to carry out exercises. He waited for an official confirmation that the exercises would be cancelled, but then heard a super-sonic noise followed by an explosion only a second apart from each other. That is when he knew something was up.

“We knew that a Su-15 was scheduled to be tested that day, but it was supposed to be flying at the altitude of 10,000 meters or higher, not 450-500 meters. It was a violation of the flight procedure.”

Leonov that day talked to witnesses that pointed at the model of a Su-15 saying that it appeared out of the clouds with its tail smoking and burning.

“While afterburning the aircraft reduced its echelon at a distance of 10-15 meters in the clouds, passing close to Gagarin, turning his plane and thus sending it into a tailspin – a deep spiral, to be precise – at a speed of 750 kilometers per hour,” Leonov tells.

According to the report that Seryogin wrote in his own hand, no aerobatic maneuvers or spins were to be performed by the crew of the MiG-15 with RD-45 engine and external fuel tanks, 260 liters each. Simple turns, pitching and nosedives were conducted after which Yury reported: “Codename 645, task completed, descending” Leonov explains.

“That was the last we heard from him. The control point recorded that he was at the altitude of 4,200 at the time. 55 seconds later the plane crashed.”

Leonov then was ordered to return to the Chkalovsky airfield, where he received the news that Gagarin’s plane was supposed to have run out of fuel 45 minutes ago. Leonov’s worst suspicions were confirmed when someone had called back reporting a crash site near the village of Novoselovo.

“We sent a team there which found the remains of the plane and the remains of Seryogin. No remains of Gagarin, except for his map case and a purse. So we first thought that he managed to eject. We sent a battalion of soldiers who combed the forest for the whole night. They shouted so that he could hear them, but all they found were remains of a balloon. It was only the next day that we found the remains of Yury Gagarin. I identified him by a dark mole on the neck which I had spotted just three days before. A commission was set up to investigative the cause of the crash. Gherman Titov and I were invited to take part in the probe as experts.”

The truth that was concealed reads more like a thriller story. When Leonov was given clearance to view the actual incident report all these years later, he found a great many inconsistencies. But the issue was with Leonov’s own report: it had his name on it, but was written in a different hand, with the facts jumbled up.

“It had been something like this. Marked here was a sonic spike, a blast, followed by one-and-a-half or two seconds of supersonic noise... So, when I looked at the copy, I suddenly noticed that it stated this noise interval to be 15 to 20 seconds long instead of the two seconds that I had reported. That suggested that the two jets must have been no less than fifty kilometers apart."

With the aid of computers, the fresh investigation was able to glean insight into exactly what caused Gagarin to go into a fatal spiral at breakneck speed. They did this by inputting Gagarin’s 55 second plunge together with the 750km speed at which he crashed.

“So we used a computer to figure out a trajectory that would relate to this interval of 55 seconds. And it turned out to be a deep spiral. Now, a jet can sink into a deep spiral if a larger, heavier aircraft passes by too close and flips it over with its backwash. And that is exactly what happened to Gagarin. That trajectory was the only one that corresponded with all our input parameters.”

Leonov then started going public with the story. This was followed by press conferences - some of them televised. Renowned test pilots were invited to scrutinize and challenge Leonov’s testimony.

“My guess would be that one of the reasons for covering up the truth was to hide the fact that there was such a lapse so close to Moscow”.

There is a record of General Zapolskiy talking to the Su-15 pilot that leaves no doubt of the pilot’s fault for creating such circumstances that led to the incident.

However, the name of the man responsible for Gagarin’s death is still not being disclosed. Keeping him anonymous was a condition under which Leonov was allowed to talk.

It is only known that the pilot is now 80 years old and is in poor health.

“I was asked not to disclose the pilot’s name. He is a good test pilot…It will fix nothing,” Leonov said.

Nikolay Stroev, Deputy Head of the Military-Industrial Commission of the USSR said that the incident happened with no intention on his part as the pilot didn’t see the other plane in the clouds as he passed “on supersonic speed in fractions of a second, maybe 10 or 20 meters away”.

Conspiracy theories have surrounded the events of that day for years. They included suicide – even a collision with a UFO.

But for all intents and purposes, the case is closed, and the newfound truth should provide those affected with closure. Such is the conclusion of the first woman in space, Russian Valentina Tereshkova. She spoke at a press conference at the UN headquarters in Vienna, where she participated in a conference of the Committee for the Peaceful Use of Outer Space.

“The only regret here is that it took so long for the truth to be revealed,” she said. “But we can finally rest easy.”

Gagarin’s passing was not only a tragedy, but a career-ending moment for Tereshkova. The state simply wouldn’t let her fly anymore, as the possibility of losing a second cosmonaut of such stature would have been simply catastrophic.

“They forbade me from flying ever again, even piloting planes. The repercussions of the death of one cosmonaut were so great that they wanted to keep me safe.”

But the source of Tereshkova’s deepest sadness still lies with Gagarin’s passing. She tried to hold back tears, as she spoke: “I still miss him. It is a loss not only for us cosmonaut colleagues, but for the entire community.”