The Indian Air Force on its 87th birthday today sprung a surprise on Pakistan in response to its claim of shooting down a Sukhoi-30MKI in February. In the clear skies above Hindon Air Force Station near Delhi, three nimble French-origin Mirage-2000s flanked by two larger Sukhoi-30MKI multirole fighter jets flew in what is known as the "Avenger" formation as the spectators below cheered for them.