Following reports of a loud boom heard in the Figueira da Foz region this Monday, April 27, at 12:30 pm, the Air Force revealed on Tuesday that it originated from an F-16M operational mission for air defence, which required breaking the sound barrier. The Air Force stated that such activity is essential for national readiness and that atmospheric conditions may have amplified the shockwaves. They assured the public that there was no danger, as it was a routine operation. Witnesses on the ground reported a sound like distant thunder followed by a shockwave that shook buildings.