Indicating this, the Chief of the Air Staff, Air Chief Marshal S. Krishnaswamy said the court of inquiry ordered to probe the crashes, suspected due to sudden engine flameout, had cleared the upgraded version for flying operation.

“The go ahead in flights on upgraded versions would be given later this week”, he said.

The Indian Air Force has ordered upgradation of a total of 125 of MiG-21 BIS fighter with Russian and Israeli help with Air Marshal Krishnaswamy saying that the entire fleet would be inducted into the IAF by 2004-2005.

Ten upgraded aircrafts have already been inducted into the IAF. The upgraded version MiG-21-93 are powered by the same R-25 engines, the types which allegedly failed causing last week’s crash of older MiG-21 type 75 variants.

Following rising concern over a spate of MiG-21 crashes, Russian experts have been called in to join the probe into the failures of the fighter jet engines.

Russian experts have flown in here to join technicians from the Hindustan Aeronautics and the IAF to examine the R-25 engines following the crash.

Top IAF officials said the experts would carry out comprehensive checks on the R-25 engines adding that though the upgraded jets were powered by the same engines, it had more sophisticated ancillary systems and more powerful gearbox. “Nevertheless checks would also be carried out in these aircraft,” they said.

On the upgradation programme the air chief said that it will continue as scheduled.

The crashes had led to the grounding of 72 of these fighters powered by the same engines now being manufactured here under licence from Russian Mikoyan bureau.

On these grounded squadrons Air Marshal Krishnaswamy said aircraft examinations would be done minutely squadron-by-squadron, indicating that a court of inquiry might be given more time to allow experts to have a thorough check of these aircrafts.

A total of 84 MiG-21 fighters had crashed during the past five years, prompting two key Parliamentary committees — Public Accounts Committee and Standing Committee — to demand phasing out of the aircraft.