"The materials in our possession and the results we already have allow us to say that the investigation will be completed in October," said Tatyana Anodina, committee head.
The Tu-154 liner crashed in stormy weather in eastern Ukraine August 22 en route from a Russian Black Sea resort to St. Petersburg, killing all 170 passengers and crew.
Anodina said the results will be made public in St. Petersburg, where the air carrier that owned the jet is based, at the city governor's request.
The crash was the latest in a string of plane accidents to hit Russia recently. On July 9, the S-7 Airbus 310 crashed at the Irkutsk airport in Siberia, claiming the lives of 124 people and injuring 70.
Russia's Prime Minister Mikhail Fradkov has ordered stringent measures to ensure flight safety on Russian airliners. He directed Defense Minister Sergei Ivanov, who is also a deputy prime minister, to take charge of the efforts.
"Your approach to this work should be decisive and severe," Fradkov told the defense minister. "If the conclusions lead to structural changes or a personnel reshuffle, I am willing to consider them and make the decisions if necessary."
Prosecutors and aviation watchdog members conducted inspections at St. Petersburg's Pulkovo airport and Pulkovo Airlines, the crashed Tu-154's owner, in early September and opened several administrative offence cases against the companies.
Inspectors criticized the runways and pointed to ongoing landing incidents caused by poor runway maintenance, encounters with birds, poor discipline among crewmembers and violations by them of rules for crews and aircraft.