What happened
On 10 July 2014, a scheduled domestic flight, Expressways 336, was on final approach to runway 26 at Port Elizabeth aerodrome. The aircraft, a Bombardier CL600 registered ZS-NMF, was carrying 27 passengers and 3 crew members. While the aircraft was on approach, the air traffic controller cleared SAA410, an Airbus A320 registered ZS-SZZ, for an "immediate" takeoff, explicitly instructing the crew not to stop on the runway.
As the Bombardier CL600 continued its approach, the flight crew identified insufficient separation between themselves and the departing Airbus A320. The crew elected to execute a go-around, a decision that was nearly simultaneous with a direct instruction from the controller to do the same. During the maneuver, the crew received a TCAS Resolution Advisory (RA) warning. Radar data confirmed a critical loss of separation, with the aircraft positioned only 263 feet vertically and 0.2 nautical miles horizontally from one another. The crew of ZS-NMF managed the situation visually, avoiding a descent that might have triggered ground proximity warnings, and eventually landed safely.
The investigation
SACAA AIID examined the communications and radar tracks at Port Elizabeth aerodrome. The investigation revealed that the controller was managing four different aircraft, including a calibration aircraft, while simultaneously providing training to a student controller. The investigation also noted that the controller used non-standard phraseology, specifically telling the approaching crew "landing assured," a term the operator confirmed is not standard air traffic terminology.
Findings
- The controller failed to effectively monitor the progress of the aircraft on final approach, leading to the loss of separation.
- The controller cleared the departing aircraft for an immediate takeoff before the approaching aircraft had passed.
- The controller allowed both horizontal and vertical separation to drop below required safety minimums.
- High workload contributed to the incident, as the controller was managing multiple aircraft and supervising a student.
- The use of non-standard terminology created potential confusion during the approach.
Safety action
- It is recommended that controllers should not be tasked with training students while simultaneously managing calibration flights at a licensed aerodrome.
- Recommendations were made to ensure controllers are familiar with all flight calibration procedures.
- The investigation suggests that training for controllers should be conducted during periods when more than one controller is on duty to manage peak workloads.