Bay of Biscay

The floatplane was involved in a maritime patrol flight when it was shot down by a German submarine. Out of control, it crashed into the Bay of Biscay, off the Spanish coast. No trace of the aircraft nor the crew was found.
Crew (201st Squadron):
S/L William Dennys Butterworth, pilot,
F/O Colin John Griffith, pilot,
F/S John Charles Leleux, flight engineer,
F/S James William Hobson, flight engineer,
F/O Peter Anthony Cavendish Hunt, navigator,
F/O Anthony Valentine Philp, wireless operator,
F/S Duncan Jamieson McCormick Currie, wireless operator and air gunner,
Sgt Dennis Edward South, wireless operator and air gunner,
F/S Dennis Sharland, air gunner,
Sgt Frederick Foster, air gunner,
Sgt Jesse Robert French, air gunner,
F/S Edwin Watson, air gunner.

The crew was involved in a maritime patrol flight over the Bay of Biscay and left RAF Pembroke Dock at 1810LT on June 11. The floatplane should return to its base on June 12 with an ETA at 0725LT but failed to arrive. The British authorities confirmed that no trace of the aircraft nor the crew was found and that the aircraft has probably been shot down during the night by enemy fire, maybe by a German night fighter or a submarine.
Crew (228th Squadron).
Source: ASN

Short Sunderland flying boat T228 took off from RAF Station Pembroke Dock at 0715LT on 24 December 1943 to carry out an anti-submarine patrol. At 1225LT a distress signal was received from the aircraft. At this time T228 was over a force of enemy destroyers and in company of another Sunderland. At 1310LT a message was received from the other Sunderland aircraft which stated that wreckage of a Sunderland aircraft had been sighted and one survivor seen on the wing float of the aircraft. A dinghy was dropped but the survivor disappeared a few minutes later. Although the crew of the accompanying aircraft did not actually see T228 shot down, it was believed that T228 was shot down by an enemy surface vessel.
Source:
http://www.aviation-safety.net/database/record.php?id=19431224-0

The crew left Rabat at 2340LT on November 17 bound for RAF Coningsby. While overflying the Bay of Biscay north of the Portuguese coast, the aircraft was lost around 0555LT, probably after being shot down by a German fighter. No trace of the aircraft nor the crew was found.
Crew (617th Squadron):
F/Lt E. E. G. Youseman, pilot,
F/S S. Wittingham,
F/O E. Fleshka,
F/O W. C. Grimes,
W/O A. Laughland,
F/Sgt R. Florence,
W/O J. B. O'Grady.

While approaching the Spanish coast, the aircraft was shot down by the pilot of a German fighter and crashed into the Bay of Biscay, killing all 12 occupants.

Shot down by the pilot of a German fighter (JU.88) over the Bay of Biscay, while on a patrol flight. No trace of the aircraft nor the crew was ever found.

Shot down by the pilot of a German fighter (JU.88) over the Bay of Biscay. The captain was able to ditch the aircraft and all occupants were rescued while the aircraft sank.

The airplane departed RAF Syerston at 2230LT on July 12 on an operation to Torino. Last heard by base at 0630LT the following morning while returning to base. Calling on w/t and indicating the Lancaster was under attack from fighters. The transmission ceased abruptly. It is believed that the airplane crashed somewhere into the Bay of Biscay off the French coast. Lost without trace.
Crew (106 Sq):
F/O Colin Hayley, pilot,
Sgt Ernest Horton, flight engineer,
F/O Melvin Olaf Hovinen, navigator,
Sgt Harry Walker Millar, bomb aimer,
Sgt Kenneth Graham Rathbone, wireless operator,
Sgt Robert William Ball, air gunner,
Sgt Harold Charles Hambling, air gunner.

The airplane departed RAF Bottesford at 2242LT on July 12 on an operation to Torino. It failed to return to base and is believed to have crashed somewhere into the Bay of Biscay. Lost without trace.
Crew (467 Sq):
F/Lt Robert Winton Arnold Gibbs, pilot,
Sgt Ernest Anthony Roper, flight engineer,
F/O Sidney Gordon Norris, navigator,
F/O James Edmund Pearce, bomb aimer,
Sgt Desmond John Banks, wireless operator,
P/O Stanley O'Connor Tate, air gunner,
Sgt Donald Alexander Chisholm, air gunner.

The airplane departed RAF Warboys at 2248LT on July 12 on an operation to Torino. It failed to return to base and is believed to have crashed somewhere into the Bay of Biscay. Lost without trace.
Crew (156 Sq):
P/O James Joseph Hewerdine, pilot,
Sgt Thomas Edward Dickins, flight engineer,
Sgt Leonard William Dallimore, navigator,
Sgt John Alan Walker, bomb aimer,
Sgt James Frederick William Cullum, wireless operator,
Sgt Henry Herbert George Sickelmore, air gunner,
Sgt John Archibald, air gunner.