Synopsis
On 28 January 2001 at approximately 0900Z, a Pitts S-1S (registration ZS-MEL) and a Cessna 172 (registration ZS-LEX) were operating in the Pretoria General Flying Area 1 near Freeway Aerodrome. Both aircraft had departed from Wonderboom Aerodrome. The Cessna 172 was conducting a training flight with an instructor and a student on board. The Pitts S-1S was being flown by a private pilot.
Sequence of Events
The flight crew of the Cessna 172 reported that they entered the general flying area from the south-eastern corner over the Ludwig rose farm after receiving clearance. They switched to the area frequency (124.4 MHz) and the student made a position report at 0854Z. Around 0857Z, as they approached Freeway Aerodrome and prepared for exercises, the Pitts S-1S passed their right wing in a near-vertical climb attitude, approximately 10 to 20 meters away. The instructor contacted the Pitts pilot, who denied executing an aerobatic manoeuvre and stated that he had the Cessna in sight throughout.
The pilot of the Pitts S-1S indicated that he heard the Cessna's broadcast while en route to Wonderboom and saw the aircraft approaching but about 500 feet lower. He executed a right-hand turn and stated that he passed the Cessna on its right at roughly 300 meters distance. During the turn, the aircraft gained speed, resulting in a climbing attitude as he passed. He maintained that he had visual contact with the Cessna the entire time.
Aircraft and Pilot Information
The Pitts S-1S (ZS-MEL) had its last annual inspection certified on 1 December 1999 at 640.05 airframe hours. It was not clear from the documentation whether all applicable airworthiness directives and service bulletins had been complied with during that inspection. The pilot held a private pilot license, was 41 years old, and had approximately 650 total flying hours with about 100 hours on type.
The Cessna 172 (ZS-LEX) had its last mandatory periodic inspection certified on 3 January 2001 at 7414 airframe hours. Records indicated that required airworthiness directives and service bulletins were compiled with. The aircraft was operated by an instructor (commercial license, 30 years old, 4264 total hours, 1476 on type) and a student.
The Aircraft Maintenance Organization (AMO 142) that serviced ZS-LEX was audited and held a valid approval until 1 August 2001.
Probable Cause
The pilot of ZS-MEL flew in close proximity past ZS-LEX, while performing an aerobatic manoeuvre.