Mona AFB

The crew was engaged in a night training flight. While cruising at an altitude of 3,000 feet, the twin engine aircraft hit the east slope of Mt Foel Fras near Carneddau. Rescuers arrived on the scene around 0830LT and four crew members were evacuated while the instructor was killed.
Crew (8th AFU):
F/S Alan Biffen, pilot,
F/S Albert Francis Standring, wireless operator and instructor, †
P/O Victor Joseph Sibthorpe, navigator,
Sgt Dalton, air bomber,
Sgt Lorrimer, wireless operator.

The crew was performing a cross country training exercise on behalf of the 8th AFU. The twin engine aircraft left RAF Mona, in Anglesey, at 1505LT. While cruising north of Wale at a height of some 5,000 feet, the pilot made a left turn when he lost control of the aircraft that dove into the ground and crashed in an open field. All five occupants were killed.
Crew:
Sergeant Melville O. Samuels, pilot,
Sergeant Thomas M. Clothier,
Charles H. M. Folkard,
Lieutenant Jan M. Radecki,
Sergeant Sylvester K. Yates.

The crew was performing a gunnery exercise from RAF Mona. While flying along the coast, the plane tried to fly between the shore and a large hopper which linked the Granite Quarry on the Slopes of Gyrn Ddu. This quarry was linked to a jetty by a transporter cable to support the cars from the mine workings above the village. The Anson flew into the cable, went out of control and crashed into the sea 100 yards offshore. Three crew members were killed while three others were injured.
Crew (3rd AGS):
Sgt R. W. Eastman,
F/O Harold Stevens, pilot, †
Sgt Ivor Ormondroyd, air gunner,
Sgt T. H. Jeffs, air gunner, †
Ronald Albert Cashen, †
John White.
Source: http://aviation-safety.net/wikibase/wiki.php?id=25175

The crew was performing a local training flight at RAF Mona. On final approach, the airplane struck a boulder and crash landed. It was damaged beyond repair and all four crew members escaped unhurt.

The crew was performing a local training exercise at RAF Mona. On final approach, while on an overshoot, the airplane collided with a RAF Blackburn B-26 Botha registered L6373 that was on approach to land. Both airplane crashed and were damaged beyond repair. There were no fatalities.

The crew was performing a local training exercise at RAF Mona. On final approach, the airplane collided with a RAF Avro 652 Anson registered LT528 that was overshooting. Both airplane crashed and were damaged beyond repair. There were no fatalities.