British European Airways Flight 706 was a scheduled flight from London-Heathrow Airport (LHR) to Salzburg-W. A. Mozart Airport (SZG), by Vickers Vanguard G-APEC, on 2 October 1971. Whilst en route at 19,000 ft (5,791 m), 35 minutes after takeoff, the rear cabin pressure bulkhead failed. The resulting depressurisation of the tail section caused the surfaces of the tailplanes to separate, weakening them to the point that they broke off. Without a horizontal stabiliser the aircraft entered an uncontrollable dive. The aircraft crashed near Aarsele, Belgium, killing all 63 passengers and crew on impact.
Links: en.wikipedia.org, aviation-safety.net, www.planecrashinfo.com