Did a fighter aircraft, a Sukhoi-30 MKI, doing a test sortie over Bengaluru on Tuesday afternoon fly too fast and probably low for the comfort of citizens’ ears?
At 1.20 p.m., people living in the East and South-Eastern parts of Bengaluru were jolted by a deafening burst. Residents of almost half of the city reported on social media platforms that they felt tremors and rattling of window panes and objects at home.
They first suspected an earthquake, a theory which officials of the State disaster monitoring agency KSNDMC quickly dismissed.
The sound was heard as a boom, thunder, blast, and felt across Marathahalli, areas around Hindustan Aeronautics Ltd. on Old Airport Road, Whitefield, Electronics City, Fraser Town, Kammanahalli, football stadium, Ulsoor, Bannerghatta Road, Jayanagar, and JP Nagar, among other areas. It was reportedly also heard at Anekal, 35 km away, and Malur, about 50 km away.
ASTE (Aircraft & Systems Testing Establishment) of the Indian Air Force is located in the HAL belt at Marathahalli. Its experienced test pilots, who guarantee that a plane is safe to fly, routinely test-fly military aircraft that are under development, or every time a military aircraft is slightly tweaked, upgraded, serviced; or a device or part on the plane is added or replaced.
According to multiple unofficial sources, a Sukhoi-30 MKI fighter plane, probably being test flown by ASTE pilots, was flying over the city around the time.
It may have gone supersonic — that is, breached the speed of sound (beyond Mach 1 or around 1,200 km per hour). As the plane flies, depending on the height, the high speed creates “sonic boom” or sound waves that ‘hit’ the areas below. The present boom was one such, a former senior technical officer of the IAF said. If this sortie needed to test the speed or height, it could have ideally flown over fields around Bengaluru, the former IAF engineer said.
The IAF’s Headquarters Training Command based in the city somewhat corroborated this. “No aircraft of the training command was flying in the area. However, ASTE and HAL could have been undertaking their routine test flying, which necessitates going supersonic at times. These are done well beyond the city limits in specified sectors,” said an HQTC release issued in the evening.
“However, considering the atmospheric conditions and reduced noise levels in the city during these times, the aircraft sound may become clearly audible even if it happened way away from the city,” it added.
HAL spokesman Gopal Sutar said: “HAL aircraft or test flights have nothing to do with today’s sound in Bengaluru.”
Initially, a few residents suspected a cooking gas cylinder burst in the area. Another theory was the burst was due to the build-up of cyclone Amphan in the Bay of Bengal.
Earlier in the day, Bengaluru Police Commissioner Bhaskar Rao said he had asked the Air Force Control Room if a plane had caused it.
Karnataka State Natural Disaster Monitoring Centre said: “The activity reported in Bengaluru is not due to earthquake. The seismometers did not capture any ground vibrations as generally happens during a mild tremor. The activity is purely a loud unknown noise.”