Tupolev expects to complete the certification flight regime for the Tu-204SM within the next few weeks, with just a couple of outstanding tests remaining.
The Russian design bureau says that "almost all of the tests are finished" with the exception of those dealing with high-intensity icing.
Tupolev says the flight certification exercises will be completed in April-May.
The twinjet, a modernised version of the baseline Tu-204, previously underwent low-temperature testing at Yakutsk in February last year.
During these sessions it was subjected to short-term and long-term exposure, lasting about 2h and 12h respectively.
Tupolev adds that high-temperature tests were subsequently performed in the United Arab Emirates in August, while wet-runway trials were conducted the following month.