Complex sentence: She can be consider as the 1st production aircraft because she was delivered to Aeroflot and equipped for commercial use.On 26th December 1975 did the first operational flight between Moscow and Alma-Ata carrying cargoes and mail.
Split into simpler sentences: She can be considered the first production aircraft, as she was the first to be equipped for commercial use and delivered to Aeroflot. The first operational flight was on 26th December 1975 between Moscow and Alma-Ata carrying cargo and mail.