The Finnish Air Force carried out an operative flight on Thursday during which the sound barrier was broken, says Air Force information officer Joni Malkamäki. This caused a loud sonic boom, which heard at 1.02 pm over a large expanse of Uusimaa region, which includes Helsinki.
”This involved one Hornet fighter jet,” Malkamäki told Yle.
The sonic barrier was breached as the aircraft was flying between the Sipoo and Janakkala areas of southern Finland, before it continued on south toward the Gulf of Finland.
The flight was at an altitude of about 10 kilometres.
“During certain weather conditions, the sound can be heard at a great distance,” said Malkamäki.
The Air Force declined to comment on the reason for the operation, but says that it would have announced immediately if it involved a violation of Finnish airspace. Last year there were several incidents when Finnish jets were scrambled in response to suspected airspace intrusions, causing at least two sonic booms -- once almost exactly a year ago on May 20, 2014.
Late Thursday morning, the Swedish Air Force dispatched two Jas Gripen fighter jets to carry out surveillance of two Russian Tu-22M bombers’ flight paths over the Baltic Sea, near the island of Öland.