Moscow, Aug 21 (IANS/RIA Novosti): Russian fighter maker Sukhoi's T-50 fifth-generation stealth fighter has completed initial approach trials to a flight refuelling aircraft, the company said Tuesday.

The aircraft, T-50-2, made approaches to an Il-78 tanker in company of a Su-25UB trainer/strike aircraft.

The second prototype, T-50-2 is currently conducting a range of flight trials to test the new plane's flight envelope in subsonic and supersonic regimes and in different configurations.

The first prototype, T-50-1, is undertaking preparation for a flight test programme involving flight at super-critical angles of attack and super-maneuverability.

In August, T-50-3 will start full tests of the aircraft's new active phased-array radar system and avionics, which the company says has already shown impressive results in air-to-air and air-to-ground tests.

The NII Tikhomirova radar will allow T-50 to attack targets at long-range in simultaneous air-to-air and air-to-surface modes, detect and classify group and single targets and simultaneously attack several targets at once with precision-guided weapons and also perform electronic warfare functions.

A fourth T-50 will join the test programme later this year.

The T-50 is due to enter Russian Air Force service after 2015. A derivative of the aircraft is also due to enter service with the Indian Air Force at a slightly later date.