German aviation expert and retired pilot Peter Haisenko, who worked as first officer and captain for Lufthansa for 30 years, believes that the plane was flown into the ground.
“I suspect it could be a controlled flight into terrain, but for what reasons remains completely unknown,” he told Sputnik.
Flight recorders from the crashed plane have been transferred to experts. The Russian government commission is cooperating closely with Cairo to investigate the circumstances of the crash and to assist the families of the victims.
According to Haisenko, posted images and media reports suggest that the aircraft "struck the ground with the tail first, and the tail got separated because of that impact and was not destroyed by the fire" while "the rest then crashed and went up into flames."
At the same time, Alexander Smirnov, deputy director of Kogalymavia Airlines, owner of the ill-fated A321 passenger plane, excluded human and technical factors as a cause in the crash.
Julian Bray, an aviation and security expert, said that a wide range of reasons might be behind the crash, but none of the reasons debated at the moment can be exclusively relied upon.
“It could have been sabotage, it could be technical, it could be pilot suicide, which I doubt, so there is nothing we can say at the moment that actually stands up,” Bray told Sputnik.
Bray added that reports that the Islamic State (ISIL) jihadist group is responsible for the crash are not realistic, because the altitude of the flight — 31,000 feet — made the plane unreachable for the militants.
Bray did not exclude the explanation that "something" might have been planted on board which could have exploded later.
"Anything is possible, it could have been a piece of cargo, something in passengers luggage,” Bray said.
Russian officials are reserved in jumping to conclusions regarding the cause of the tragedy. Both the Kremlin and the Russian Foreign Ministry have called to wait for the official results of the investigation.
"No version can be excluded at the moment as the investigation is in the most early stage. Which version will be considered the primary lead as the investigation advances is hard to say right now," Kremlin spokesman Dmitry Peskov said Monday, answering a question as to whether the crash could have been caused by a terrorist attack.