2017 South African mid-air near miss between Comair and SA Airlink aircraft (ZS-ZWS)

Incident Overview On 13 March 2017, flight BA6234, operated by Comair Ltd / SA Airlink (Pty) Ltd and registered ZS-ZWS, was a Boeing 737-800 on a scheduled domestic passenger flight from Port Elizabeth Aerodrome (FAPE) to OR Tambo International Aerodrome (FAOR). The aircraft carried six crew members and 130 passengers. Flight SA8053, registered ZS-SNX, was an Embraer ERJ135 (Embraer 135-LR) on a scheduled international flight from Moshoeshoe International Aerodrome near Maseru, Lesotho (FXMM) to OR Tambo International Aerodrome (FAOR). It carried three crew members and 16 passengers. ## Sequence of Events Both aircraft were flying in a northeasterly direction toward waypoint IMGEV under radar control. SA8053 was at its cruising altitude of FL370, while BA6234 was cruising at FL410. Johannesburg Area South East cancelled BA6234’s standard arrival and instead routed the aircraft direct to waypoint ETLIG. This routing placed BA6234 too high for the flight management computer’s vertical bearing. BA6234 was cleared to descend from FL410 to FL380. The descent began one minute and twenty seconds after the clearance. After the rerouting instruction was entered into the flight management computer, the computer recalculated a position that placed the aircraft too high on the descent profile. The first officer initiated an increased rate of descent to recapture the appropriate descent profile. During the descent, a traffic advisory was generated by the traffic collision avoidance system. This was followed almost immediately by a resolution advisory in both aircraft. Both crews complied with the resolution advisory. At the point of levelling off, BA6234 had exceeded its cleared altitude by approximately 500 ft. The safe clearance distance between the two aircraft was 500 ft and 1.6 nm. Once separation was regained, both aircraft continued safely to their destination. ## Aircraft and Personnel The pilot-in-command of ZS-ZWS was a 45-year-old South African male with an airline transport licence and 12,017 total flying hours, including 6,762 hours on type. The first officer was a 34-year-old South African male with 9,417.3 total hours and 584.5 hours on type. The pilot-in-command of ZS-SNX was a 33-year-old South African male with 4,401.5 total hours and 1,680.5 hours on type. The first officer was a 25-year-old South African male with 2,196.3 total hours and 59.3 hours on type. ## Outcome No persons were injured or killed. Neither aircraft sustained damage as a result of the loss in separation. No other damage was caused.