Howden Moor / Sheffield Incident (1997).
disputedclose_encounterRendlesham Forest (RAF Bentwaters/Woodbridge)
On the night of 24 March 1997, residents near Bolsterstone (Peak District/Sheffield border) reported a low-flying 'small plane', a flash and plumes of smoke. A ~50-square-mile, ~200-personnel search costing over £50,000 found no wreckage. The British Geological Survey recorded two unexplained sonic booms at 21:52 and 22:06; an earlier triangular UFO was also reported.
Disputed because the seismic records, search operation and parliamentary discussion are factual, but the 'UFO engaged by scrambled RAF Tornados' story is uncorroborated and officially denied. Investigators (David Clarke, Martin Jeffrey) judge the balance of probabilities favours low-flying military training aircraft, with bolide-meteor and misperception (heightened by Comet Hale-Bopp) as contributing factors.