Investigation Summary
The aircraft was conducting a test flight for the renewal of its Certificate of Airworthiness, carrying a total of 12 BOAC personnel. After completing the required maneuvers at 12,000 feet, the crew requested clearance to descend to 3,000 feet, likely intending to approach Hurn Airport due to deteriorating weather at Heathrow. However, the crew had misread the three-pointer altimeter, a known ergonomic hazard of the era. They believed the aircraft was at 11,500 feet when it was actually at 1,500 feet. Consequently, when they initiated the descent, they flew directly into the ground within three minutes. The thick fog present across southern England at the time provided a visual illusion of cloud cover, preventing the pilots from realizing their proximity to the ground until impact. The aircraft struck telephone lines and trees before crashing into a field at Sopley Park near Winkton, breaking apart and catching fire. Rescue efforts were hampered by the lack of four-wheel drive vehicles and radio communications among local fire appliances, though three survivors, including the First Officer, were eventually pulled from the wreckage. All nine fatalities were BOAC employees, as the flight was a non-revenue technical operation.
Final Conclusions
The investigation concluded that the primary cause was the failure of the Captain and First Officer to correctly establish the aircraft's altitude before and during the final descent. The responsibility for the accident was placed on the Captain. A significant contributory factor was the design of the three-pointer altimeter, which required a higher degree of concentration to interpret accurately than was desirable for a vital flight instrument. While the original 1950s report describes the event as flying into ground obscured by fog due to instrument misinterpretation, modern aviation analysis classifies this accident as Controlled Flight Into Terrain (CFIT).
Video Analysis
No video analysis linked for this case file yet.
Systems & Failure Modes
Three-pointer Altimeter
A flight instrument using three separate needles to indicate hundreds, thousands, and tens of thousands of feet. The investigation found the display was difficult to interpret quickly, leading to a 10,000-foot reading error.
Interesting Facts
- 01The aircraft was a Bristol Britannia 312, registration G-AOVD, MSN 13235, manufactured in 1957.
- 02The flight was a non-scheduled test flight for the renewal of the aircraft's Certificate of Airworthiness.
- 03The crew misread 1,500 feet as 11,500 feet due to the three-pointer altimeter design.
- 04The crash site was located at Sopley Park and Winkton, near Christchurch.
- 05Nine people were killed in the accident, all of whom were BOAC employees, including two of the three flight crew members.
Safety Actions & Advisories
Altimeter Replacement Directive
The Ministry of Transport ordered the replacement of all three-pointer altimeters in British registered aircraft operating above 20,000 feet by September 1959.
Instrument Display Standards
New requirements were introduced for altimeters to display a cross-hatch or chequered flag when indicating altitudes below 1,500 feet to prevent low-altitude misinterpretation.
Emergency Response Upgrades
Local fire services in Christchurch were equipped with radios and four-wheel drive appliances to improve response capabilities in rural terrain.