Royal Air Force and replacement by the F-35, the RAF Lossiemouth-based 15 (Reserve) Squadron (the Tornado Operational Conversion Unit) was disbanded in March 2017. Lightning: On 23 November 2015 it was announced that a total of 138 F-35Bs will be ordered. 617 (The Dambusters) Squadron officially reformed on 18 April 2018 as an RAF Lightning Squadron. The first four aircraft arrived at RAF Marham on 7 June 2018. The Sentry AEW1, based at RAF Waddington, provides airborne early warning to detect incoming enemy aircraft and to co-ordinate the aerial battlefield. The Sentinel R1 (formally known as ASTOR – Airborne STand-Off Radar) provides a
RAF Digby control at RAF Coleby Grange and RAF Wellingore. The first squadron scrambled from Digby was No. 46 Squadron on 3 September; told there was an incoming German raid they found nothing and returned. October 1939 saw a number of arrivals at the station. On 10 October No. 611 Squadron RAF flying Supermarine Spitfires and No. 229 Squadron RAF operating Bristol Blenheims arrived at Digby. Initially, No. 611 Squadron flew affiliation exercises with the other two squadrons and with other new arrivals No. 44 Squadron RAF and No. 144 Squadron RAF, who were both equipped with Hampden light bombers. At the