BOAC Flight 777

BOAC Flight 777 was a KLM flight scheduled as a British Overseas Airways Corporation civilian airline flight from Portela Airport in Lisbon, Portugal to Whitchurch Airport near Bristol, England. On 1 June 1943, the Douglas DC-3 serving the flight was attacked by eight German Junkers Ju 88 bombers and crashed into the Bay of Biscay, killing all 17 on board. There were several notable passengers, among them actor Leslie Howard.

One theory suggests that the Germans attacked the aircraft because they believed that British Prime Minister Winston Churchill was aboard; another suggested that it was targeted because several passengers were British spies, including Howard. During the Second World War, British and German civilian aircraft operated from the same facilities at Portela, and Allied and Axis spies watched the incoming and outgoing traffic. The Lisbon–Whitchurch route frequently carried agents and escaped POWs to Britain.

Aircraft flying the Lisbon–Whitchurch route were left unmolested at the beginning of the war, and both Allied and Axis powers respected the neutrality of Portugal. However, in 1942, the air war had begun to heat up over the Bay of Biscay, north of Spain and off the west coast of France; the Douglas DC-3 lost in this attack had survived attacks by Luftwaffe fighters in November 1942 and April 1943.

When war broke out in Europe, the British Air Ministry prohibited private flying and most domestic air services. Imperial Airways and British Airways Ltd, in the process of being merged and nationalised as British Overseas Airways Corporation, were evacuated from Croydon Aerodrome and Heston Aerodrome to Whitchurch Airport, outside Bristol. After the fall of Norway, and the entry of the Netherlands, Belgium, France, and Italy into the war, only neutral Sweden, Ireland, and Portugal remained as European destinations for BOAC. Over the UK, civil aircraft were restricted to between 1,000 feet (300 m) and 3,000 feet (910 m) and could fly only during daylight to ease identification. The British government also restricted flights to diplomats, military personnel, VIPs, and those with government approval.

For several weeks prior to the German invasion of the Netherlands, the Dutch airline KLM operated a direct, over-water, twice-weekly DC-3 service from Amsterdam to Portugal, avoiding French, British, and Spanish airspace to connect with the new Pan Am flying boat service from the US to Lisbon. When Germany invaded in May 1940, KLM had several airliners en route outside the Netherlands. Some managed to fly to Britain, while others stranded east of Italy continued to link British and Dutch territories from Palestine to Indonesia and Australia. The British government interned the Dutch aircraft at Shoreham Airport. After negotiations, the Air Ministry and the Dutch government-in-exile contracted to use the KLM aircraft and crews to replace de Havilland Albatross aircraft on a scheduled service between Britain and Portugal, which BOAC started in June 1940 from Heston Aerodrome.

Initially, a British copilot (carrying a concealed firearm) was included in the crew. After initial reservations about using Dutch crews were overcome, all-Dutch crews were used, although the flights used BOAC flight numbers and passenger handling. The KLM contingent was housed at BOAC's Whitchurch base.

The UK–Lisbon service operated up to four times per week. From 20 September 1940, passengers were flown from Whitchurch (although Heston continued as the London terminus for KLM from 26 June till 20 September 1940), and for Lisbon, the pre-war grass airfield at Sintra was used until October 1942, when the new runway was ready at Portela Airport, on the northern edge of Lisbon. By June 1943, over 500 KLM/BOAC flights had carried 4,000 passengers.

Originally, five Douglas DC-3s and one Douglas DC-2 airliner were available. With the loss of a DC-3 on 20 September 1940 in a landing accident at Heston, and the destruction of another DC-3 in November 1940 by Luftwaffe bombing at Whitchurch, only four aircraft remained: DC-2 G-AGBH Edelvalk (ex-PH-ALE), DC-3 G-AGBD Buizerd (ex-PH-ARB), DC-3 G-AGBE Zilverreiger (ex-PH-ARZ), and DC-3 G-AGBB Ibis (ex-PH-ALI). In 1939, with war tensions in Europe increasing, KLM had painted their DC-2s and DC-3s bright orange to mark them clearly as civilian aircraft. BOAC repainted the aircraft in camouflage, with British civil markings and red/white/blue stripes like all BOAC aircraft, but without the Union Flag. They were later marked with their Dutch bird names under the cockpit windows. The interiors remained in KLM colours and markings.