Fighter Interception Unit

The Fighter Interception Unit (FIU) was a special interceptor aircraft unit of the Royal Air Force (RAF) during the Second World War. It was part of Air Defence of Great Britain.

The Fighter Interception Unit was initially set up to evaluate technological advances such as airborne interception (A.I.) equipment (an on-board interception radar) and other operational innovations, to counter increasing night raids by the Luftwaffe.

The unit was formed at RAF Tangmere in April 1940 under the command of Squadron Leader George Philip (Peter) Chamberlain, with a strength of 5 Blenheims equipped with the latest A.I. Mk III radars. Operations initially consisted of daytime practice interceptions and operational night defence flights. The night fighter Blenheims were directed several times to possible targets, in the early days of ground-controlled interception (GCI) to acquire and then maintain a radar contact, and finally to intercept target proved a very difficult task.

However, on the night of the 22/23 July 1940 they achieved the first airborne radar intercepted kill in history. A Blenheim Mk IF flown by Flying Officer G. Ashfield, with a crew of Pilot Officer G.E. Morris (Observer) and Sergeant R.H. Leyland (A.I. operator), patrolled the Sussex coast at 10,000 ft (3,000 m). They were directed to a possible intercept by the controller at Poling Chain Home radar station who reported an incoming raid. Sgt. Leyland reported a response on the A.I. at a range of 8,000 feet and presently P/O Morris made a visual sighting of a Dornier Do 17 to port and below the Blenheim. Ashfield closed the distance to 400 feet and then opened fire. Strikes were observed on fuselage and engines, the Dornier lurched to starboard and fell away, 5 miles south of Bognor Regis. The aircraft, a Dornier 17Z of 2 Staffel, Kampfgeschwader 3, crashed into the sea. The crew was later rescued from the sea. The Blenheim was so close to the Dornier during the attack that the cockpit perspex was covered in oil, resulting in Ashfield losing control and the Blenheim flipping onto its back. He was able to regain control of the Blenheim at an altitude of 700 feet and landed at Tangmere just after midnight.

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