New Delhi, Oct 31 : The Indian Air Forces's Number 4 Squadron (Oorials), based at Air Force Station Uttarlai in Rajasthan's Barmer is converting from the MiG-21 to the Su-30 MKI, the Defence Ministry said on Tuesday. Marking the end of an era, the MiG-21 Bison aircraft were seen for the last time in the skies of Uttarlai on Monday, flying aside the Su-30 MKIs to mark the occasion. The squadron known as "Oorials" has been operating the MiG-21 since 1966 and is now being re-equipped with the Sukhoi-30 MKI aircraft and this change signifies the unwavering commitment of the Indian Air Force to modernise and protect the skies of the nation, the Ministry said. According to the IAF, it is marking a watershed moment in the history of the squadron. First inducted in 1963, the MiG-21 was the first supersonic fighter in service of the IAF and has participated in all major conflicts since then. The formal induction of the new aircraft was marked by a ceremony at Air Force Station Uttarlai on Monday, including a combined flypast by the MiG-21 and Su-30 MKI, which marked the last MiG-21 sortie for the squadron. Various military and civilian dignitaries in attendance. With the conversion of this squadron to Su-30 MKI implies that the IAF now operates only two squadrons of the MiG-21. The IAF remains committed to phasing out the MiG-21 aircraft by 2025, officials said. /IANS