Sukhoi Su-27 variant
Sukhoi Su-27 Su-27S1M
The Su-27S1M is the Ukrainian Air Force's single-seat Su-27S fighter modernised under the national programme known generically as Su-27-1M. The work was carried out at the Zaporizhzhia aircraft repair plant (ZARZ "MiGremont"), with the participation of Ukrainian avionics industry — among others "Orizon-Navigatsiya" and "Novator" — and combined airframe service-life extension with the installation of an additional equipment kit. The programme began in the early 2010s and was completed administratively on 5 August 2014, when order No. 499 of defence minister Valeriy Heletey formally adopted four modernised variants into the Ukrainian Air Force: the Su-27S1M and Su-27P1M fighters and the Su-27UB1M and Su-27UP1M two-seaters. The modernisation touches neither airframe nor engines: the Su-27S1M remains a Soviet-built Su-27S. What changes is the onboard equipment. The N001 radar sighting station was updated with new receiver blocks, and an SN-3307-02 satellite navigation receiver, ICAO-compliant radio navigation and communications equipment (Kurs-93M-V and an A-511 transponder) and a solid-state SAVR-27U audio-video recording system were added. The stated aim was to bring the aircraft closer to NATO interoperability requirements without rebuilding the weapon system. The Su-27-1M programme as a whole has covered, according to available counts, no fewer than twenty-two aircraft across the four subvariants.
History
A national programme born of circumstance
Ukraine inherited a sizeable Flanker fleet from the Soviet Union and no easy access to the manufacturer. The answer was a domestic modernisation, executed at the Zaporizhzhia plant with Ukrainian suppliers, focused on what could be done without the original design bureau: airframe overhaul, replacement of obsolete electronics, and adaptation to Western navigation and communication standards.
Timeline
Service-life extension and modernisation work began in the early 2010s; sources place the start in 2012 or 2013 depending on how they count the first airframes. Formal recognition came on 5 August 2014 with ministerial order No. 499, which adopted all four variants of the family at once.
What changes relative to the Su-27S
The package is avionics rather than weapons or propulsion: an upgraded N001 radar station with new receiver blocks, an SN-3307-02 GPS receiver, the Kurs-93M-V suite and an A-511 transponder for ICAO-compliant operation, and a solid-state SAVR-27U recorder. The stated purpose covers short- and medium-range air combat in any weather and at any time of day, and the flying training of pilots in operational units.
After 2022
The Russian invasion of 2022 accelerated the adaptation of Ukrainian Flankers, with pylons and adapters for Western weapons appearing. Those integrations have been documented for the Su-27 fleet in general and are not always explicitly attributed to the S1M standard, so they are recorded here as context rather than as a feature of the variant.