The Russian Air Force will now receive the first T-50 PAK-FA fifth-generation fighter in 2015, instead of 2013, as requested by Russian Premier Vladimir Putin.
Col. Gen. Alexander Zelin said he hoped that in 2013, the [Sukhoi] PAK FA prototype would be ready and fine-tuned, and the air force would start deliveries to military units in 2015, according to Ria Novosti.
The air force will acquire the PAK FA fighters to replace the its aging MiG-29 Fulcrum and Su-27 Flanker.
The air force conducted the maiden flight of the aircraft on 29 January 2010, with a prototype known as T-50.
Following the 47-minute maiden flight, Putin said the first batch of fifth-generation fighters would go into service in 2013.
Designed by the Sukhoi design bureau, the T-50 is equipped with next-generation air-to-air, air-to-surface and air-to-ship missiles and two 30mm cannons.
The Russian Air Force is designing the PAK FA, with advanced avionics, stealth capability, a ferry range of up to 5,500km and an endurance of 3.3 hours, to compete with US F-22 Raptor.
Russia, which has been developing the fifth-generation fighter since the 1990s, has hailed the PAK FA as a unique warplane that combines the capabilities of an air superiority fighter and attack aircraft.