What happened
On 22 April 2014, a flight departed from Cape Town International Airport (FACT) bound for Swartwater in the Limpopo Province. The flight was being conducted under Instrument Flight Rules (IFR) with a pilot and one passenger on board. Roughly 16 minutes into the climb, while the aircraft was transitioning between 13,500 and 17,000 feet, air traffic control notified the pilot that the Mode C transponder was displaying incorrect altitude information, suggesting a descent while the pilot believed the aircraft was climbing.
In an attempt to fix the intermittent data, the pilot tried to recycle the transponder, but the error persisted. Due to the unreliable altitude reporting, air traffic control instructed the pilot to descend to flight level 135. Following this, the pilot received clearance to climb to flight level 195. During this phase of flight, the aircraft experienced a sudden and extreme increase in speed, surpassing both its maximum structural cruising speed (VNO) and its never-exceed speed (VNE). This resulted in a catastrophic structural failure in mid-air. The wreckage was located spread across a 1.58km area within mountainous terrain. There were 2 fatalities involving both occupants.
Findings
Investigations into the accident suggest that the pitot-static system, which provides essential pressure data to the altimeter and airspeed indicator, was likely obstructed by sand or dust. This blockage led to inaccurate instrument readings, causing the pilot to inadvertently exceed the maximum structural airspeed of the aircraft, leading to the in-flight breakup.