5 fatalities

1943 Night Navigation Exercise Crash in Snowdonia (N9855)

Bangor, United KingdomFlight

On November 8, 1943, an Avro 652 Anson (registration N9855) operated by Royal Air Force - RAF was involved in an aviation accident near Bangor, United Kingdom in flight. 5 people were killed. Investigators recorded the probable cause as: The aircraft drifted off course due to uncorrected wind effects, leading to a controlled flight into terrain on the slopes of Pen yr Ole Wen. This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A); 8 related events involving the same aircraft type or operator are linked below.

Sourcesthe Bureau of Aircraft Accidents Archives (B3A)Primary reportUpdated 2026-08-05Data APIEditorial standards

A five-crew aircraft crashed into the slopes of Pen yr Ole Wen during a night navigation exercise on November 8, 1943. The impact resulted in the destruction of the airframe and fatal injuries to all personnel aboard.

What happened

On the evening of November 8, 1943, a crew of five departed from RAF Halfpenny Green for a night navigation exercise. The planned route covered approximately 320 miles, passing near Rhyl, Conwy, Douglas, and Maughold Head before returning to base. Shortly after takeoff, the aircraft was tracked by RAF Tilstock with a QDM of 0500, placing it roughly four miles northwest of Shawbury on course for Rhyl.

Subsequent plotting by the Royal Observer Corps indicated the aircraft was flying a direct track from Wrexham toward Conwy. While this route would not typically intersect with Snowdonia, a wind blowing from the west-northwest at 15 mph caused significant drift. The Court of Inquiry noted that without proper correction for this drift, the aircraft would have been pushed south of the second turning point. At approximately 20:30, observers reported seeing a fire near Carnedd Dafydd. Just prior to this observation, the aircraft impacted the upper slopes of Pen yr Ole Wen while flying in a north-westerly direction.

The crash caused severe structural damage; the engines were torn from the airframe, and the wreckage rolled nearly 1,000 feet down the mountain. Fuel tanks ruptured upon impact, igniting the contents. Although the fuselage was destroyed, it did not burn completely. All five crew members perished in the accident.

Findings

The investigation highlighted the impact of atmospheric conditions on the flight path. The Court of Inquiry specifically remarked that the 15 mph wind from the west-northwest caused the aircraft to drift south of its intended track if correction was not applied. This deviation led the aircraft into the mountainous terrain of Snowdonia, resulting in the fatal collision with Pen yr Ole Wen.

Probable cause

The aircraft drifted off course due to uncorrected wind effects, leading to a controlled flight into terrain on the slopes of Pen yr Ole Wen.