Bloody Biscay: The History of V Gruppe/Kampfgeschwader 40 by Christopher H. Goss revealed one of the most detailed versions of the attack.
The book states that BOAC Flight 777 was not intentionally targeted and was shot down when it was mistaken for an Allied military aircraft.
The account is composed of the author's analysis of events and interviews, conducted decades after the war ended, with some of the German pilots involved in the attack.

According to this account, eight Junkers Ju 88C-6 heavy fighters (Zerstörer) from the 14th Staffel of the Luftwaffe's main maritime bomber wing, Kampfgeschwader 40, took off from Bordeaux at 10:00 hrs local time to find and escort two U-boats; these aircraft belonged to the long-range fighter group known as Gruppe V Kampfgeschwader 40.
The names of four of the eight pilots are known: Staffelführer Oberleutnant (Oblt) Herbert Hintze, Leutnant Max Wittmer-Eigenbrot, Oblt Albrecht Bellstedt, and Oberfeldwebel (Ofw) Hans Rakow.
The pilots claim that before setting out they were unaware of the presence of the Lisbon to Whitchurch flights.
Due to bad weather, the search for the U-boats was called off and the fighters continued a general search.
At 12:45 hrs, BOAC Flight 777 was spotted in P/Q 24W/1785 heading north.
Approximately five minutes later, the Ju 88s attacked.
Hintze retold his account for Goss as follows: "A 'grey silhouette' of a plane was spotted from 2,000–3,000 metres (6,600–9,800 ft) and no markings could be made out, but by the shape and construction of the plane it was obviously enemy."
Bellstedt radioed: "Indians at 11 o'clock, AA (code for enemy aircraft ahead slightly to left, attack)."
BOAC Flight 777 was attacked from above and below by the two Ju 88s assigned to a high position over the flight, and the port engine and wing caught fire.
At this point flight leader Hintze, at the head of the remaining six Ju 88s, caught up to the DC-3 and recognised the aircraft as civilian, immediately calling off the attack, but the burning DC-3 was already severely damaged with the port engine out.
Three parachutists exited the burning aircraft, but their chutes did not open as they were on fire.
The aircraft then crashed into the ocean, where it floated briefly before sinking.
There were no signs of survivors.

Hintze states that all the German pilots involved expressed regret for shooting down a civilian aircraft and were "rather angry" with their superiors for not informing them that there was a scheduled flight between Lisbon and Britain.
Goss writes that official German records back up Hintze's account that Staffel 14/KG 40 was carrying out normal operations and that the day's events occurred because the U-boats could not be found.
He concludes that "there is nothing to prove that [the German pilots] were deliberately aiming to shoot down the unarmed DC-3."
This account of the German pilots and Goss's conclusions are challenged by some authorities.

The research of Ben Rosevink, a retired research technician at the University of Bristol, and son of BOAC Flight 777 flight engineer Engbertus Rosevink supplements Hintze's version.
In the 1980s, Rosevink tracked down and interviewed three of the German pilots involved in the attack, including the one who fired on BOAC Flight 777.
In a 2010 interview with the Bristol Evening Post, Rosevink stated that he was convinced of the veracity of the German account.

The following day, a search of the Bay of Biscay was undertaken by "N/461", a Short Sunderland flying boat from the Royal Australian Air Force's 461 Squadron.
Near the same coordinates where the DC-3 was downed, the Sunderland was attacked by eight V/KG40 Ju 88s and after a furious battle, managed to shoot down three of the attackers, scoring an additional three "possibles," before crash-landing at Penzance.
In the aftermath of these two actions, all BOAC flights from Lisbon were subsequently re-routed and operated only under cover of darkness.
Bloody Biscay: The History of V Gruppe/Kampfgeschwader 40 by Christopher H. Goss revealed one of the most detailed versions of the attack. The book states that BOAC Flight 777 was not intentionally targeted and was shot down when it was mistaken for an Allied military aircraft. The account is composed of the author's analysis of events and interviews, conducted decades after the war ended, with some of the German pilots involved in the attack.
According to this account, eight Junkers Ju 88C-6 heavy fighters (Zerstörer) from the 14th Staffel of the Luftwaffe's main maritime bomber wing, Kampfgeschwader 40, took off from Bordeaux at 10:00 hrs local time to find and escort two U-boats; these aircraft belonged to the long-range fighter group known as Gruppe V Kampfgeschwader 40. The names of four of the eight pilots are known: Staffelführer Oberleutnant (Oblt) Herbert Hintze, Leutnant Max Wittmer-Eigenbrot, Oblt Albrecht Bellstedt, and Oberfeldwebel (Ofw) Hans Rakow. The pilots claim that before setting out they were unaware of the presence of the Lisbon to Whitchurch flights. Due to bad weather, the search for the U-boats was called off and the fighters continued a general search. At 12:45 hrs, BOAC Flight 777 was spotted in P/Q 24W/1785 heading north. Approximately five minutes later, the Ju 88s attacked. Hintze retold his account for Goss as follows: "A 'grey silhouette' of a plane was spotted from 2,000–3,000 metres (6,600–9,800 ft) and no markings could be made out, but by the shape and construction of the plane it was obviously enemy." Bellstedt radioed: "Indians at 11 o'clock, AA (code for enemy aircraft ahead slightly to left, attack)." BOAC Flight 777 was attacked from above and below by the two Ju 88s assigned to a high position over the flight, and the port engine and wing caught fire. At this point flight leader Hintze, at the head of the remaining six Ju 88s, caught up to the DC-3 and recognised the aircraft as civilian, immediately calling off the attack, but the burning DC-3 was already severely damaged with the port engine out. Three parachutists exited the burning aircraft, but their chutes did not open as they were on fire. The aircraft then crashed into the ocean, where it floated briefly before sinking. There were no signs of survivors.
Hintze states that all the German pilots involved expressed regret for shooting down a civilian aircraft and were "rather angry" with their superiors for not informing them that there was a scheduled flight between Lisbon and Britain. Goss writes that official German records back up Hintze's account that Staffel 14/KG 40 was carrying out normal operations and that the day's events occurred because the U-boats could not be found. He concludes that "there is nothing to prove that [the German pilots] were deliberately aiming to shoot down the unarmed DC-3." This account of the German pilots and Goss's conclusions are challenged by some authorities.
The research of Ben Rosevink, a retired research technician at the University of Bristol, and son of BOAC Flight 777 flight engineer Engbertus Rosevink supplements Hintze's version. In the 1980s, Rosevink tracked down and interviewed three of the German pilots involved in the attack, including the one who fired on BOAC Flight 777. In a 2010 interview with the Bristol Evening Post, Rosevink stated that he was convinced of the veracity of the German account.
The following day, a search of the Bay of Biscay was undertaken by "N/461", a Short Sunderland flying boat from the Royal Australian Air Force's 461 Squadron. Near the same coordinates where the DC-3 was downed, the Sunderland was attacked by eight V/KG40 Ju 88s and after a furious battle, managed to shoot down three of the attackers, scoring an additional three "possibles," before crash-landing at Penzance. In the aftermath of these two actions, all BOAC flights from Lisbon were subsequently re-routed and operated only under cover of darkness.
BOAC Flight 777