Bristol Britannia 301

The Britannia 301 was the sole prototype of the Series 300, the lengthened-fuselage version with which Bristol turned its medium-range Empire-route airliner into a transatlantic transport. The Series 300 grew out of the redesign undertaken after the delays to the Series 100: Bristol revised the Type 175 into a larger airliner for BOAC, producing the Series 200 and 300, and the long-range Britannia 300LR was regarded as eminently suitable for BOAC's London–Sydney service. Whereas the Series 200 was an all-cargo variant that was never built, the 300 was a passenger-only aircraft with a fuselage stretched by 123 inches (3.1 m), able to carry up to 139 passengers (originally 99) and with medium fuel capacity. BOAC itself steered its order in that direction: of the 25 Britannia 102s ordered, the last ten were cancelled in favour of Series 300 aircraft intended for transatlantic flights.

The 301 was built at Filton as a company prototype and retained the wing and fuel capacity of the Model 100; the new fuselage was the only substantial difference from the first-series aircraft. It first flew on 31 July 1956, barely four years after the maiden flight of the first prototype G-ALBO on 16 August 1952, also at Filton. The aircraft was registered G-ANCA and, in the summer of 1956, was photographed in front of the Brabazon hangar at Filton wearing the livery of Capital Airlines, the American carrier then listed as a prospective customer for the Series 305. That American interest was genuine: the same year Bristol had sent the tenth production Britannia, G-ANBJ, on a world sales tour, and both Eastern Air Lines and TWA wished to place orders. Bristol's limited production capacity, already committed to the BOAC order, and the expected arrival of the Boeing 707 and Douglas DC-8 jets meant the opportunity passed; the Capital Airlines order was cancelled and no United States airline ever operated the Britannia.

The prototype was devoted to the Series 300 test programme at a time when the Britannia was still burdened by a troubled development. After three Comets were lost in 1953 and 1954 the Air Ministry had demanded lengthy testing; in February 1954 the second prototype, G-ALRX, had been lost on the mudflats of the Severn Estuary after an engine fire caused by a failed reduction gear, and the inlet icing problems of the Proteus engines delayed service entry by two years, until BOAC's London–Johannesburg service of 1 February 1957. The engines of the Series 300 were the Proteus 705 of 3,900 hp, used on the Series 100 and some 300-series aircraft, and the Proteus 755 of 4,120 hp fitted to the rest.

On 6 November 1957 G-ANCA was lost in the Downend air crash, in a suburb of Bristol. That day the aircraft had completed one hour and forty minutes of tests, including strain-gauge measurements on the non-standard propeller of the no. 2 engine and high-speed upset recovery manoeuvres connected with United States certification, when it returned to Filton. Shortly before noon, at about 1,500 feet and as the crew began the left turn onto the base leg, the right wing dropped and the aircraft banked steeply to the right; it recovered briefly, banked again and crashed into woodland near Overndale Road, about four miles south-east of the aerodrome. All fifteen on board, four crew and eleven technicians, were killed; nobody on the ground died, although a resident was taken to hospital when an engine and part of the wing fell beside her house and a man tiling a nearby roof broke his arm in a fall. The Minister of Transport and Civil Aviation, Harold Watkinson, reported the accident to the House of Commons the following day. The cause was never established: the investigation suspected an autopilot malfunction, possibly due to faulty wiring, and the manufacturer of the system, while denying responsibility, altered it in later aircraft; the official report concluded that the autopilot could not be ruled out as the likely cause.

With the loss of the 301 the Series 300 went on without a prototype of its own: the Belfast-built 302s were delivered to Aeronaves de México in December 1957, and BOAC's long-range 312s, in service from September 1957, flew the first-ever non-stop London–Canada service on 19 December 1957. The crash is remembered in Downend by a memorial service held at Bristol Cathedral on 19 November 1957, a plaque at Downend Folk House and another at the crash site, now called Britannia Wood, unveiled on 3 November 2007 by the widow of the captain, Hugh Statham. In November 2025 Aerospace Bristol unveiled a plaque to the 42 Bristol Aeroplane Company employees who died in the course of their duties, among them the fifteen lost at Downend.