Russian officials have blamed human error for last week's plane crash in Siberia that killed 145 people.
They also described the crew's panic as the plane plunged to the ground at full throttle.
Deputy Prime Minister Mr Ilya Klebanov, disclosing the outcome of an inquiry into one of the worst post-Soviet air crashes, said the crew of the Tupolev-154 had inexplicably pulled the aircraft into a sharp angle on its approach to the runway.
That sent it into a 22-second spiral from which no pilot, however experienced, could recover.
The deputy prime minister said the plane's equipment had been problem-free in the run-up to the crash on its third attempt to land in the city of Irkutsk. Weather and air traffic conditions had been normal.
"What we have to determine is why the crew's actions became inappropriate aboard an aircraft in perfect working order and performing an ordinary landing maneouvre in normal weather conditions," Mr Klebanov said.
With control of the plane handed to the aircraft's second officer for its final approach, Mr Klebanov said the crew's reactions had been perfectly normal until a warning sounded from onboard computers that the plane was on a dangerous course.
"Their emotional state altered sharply, subject to stress," he said. "At a certain moment, there was stress."
The crash has reopened a debate about the safety of air travel and the future of the Russian aviation industry a decade after the collapse of the Soviet Union and the breakup of Aeroflot, once the world's largest airline, into hundreds of carriers.