A sonic boom once heard in my London school playground was a part of my Cold War experience. Older boys told us ‘the war’ had started. The boom was certainly impressive. Every so often a newspaper article provides a chance glance into a world it is probably better not to know too much about. Yesterday morning the good people of Liège were treated to a sonic boom. This morning an article in La Libre Belgique explained that two Belgian F16 fighter planes had raced full speed (hence the boom) – or, as La Libre put it, ‘les F16 belges ont volé plein pot’ – to intercept an Embraer ERJ145, flying from Vienna to Luxembourg because air traffic controllers had lost touch with the crew aboard for almost ten minutes. The pilot, who (I like to think) had probably been munching a sandwich, or finishing a cup of tea, came back on the radio a few moments later and the alert was over. The F16s returned to base. But the article informed its readers that the Belgian Air Force is on standby for such interceptions twenty-four hours a day, seven days a week. In extremis, the pilots would be prepared to shoot down an aircraft, if considered a sufficient threat. This has never happened, it reported, not even when a Soviet MIG-23, abandoned by its crew, traversed Belgian air space on autopilot from East to West, before running out of fuel and crashing near Courtrai. That was on 4 July 1989. One person died on the ground. I don’t remember the MIG crash at all, but it must have been one of the more bizarre Cold War incidents.