Incident Overview
On the evening of 3 October 2023, a Beech 76 Duchess (registration ZK-JED) and a Cessna 172 (registration ZK-WFS) were operating at Ardmore Airport in New Zealand. The Beech, conducting a training flight, had three pilots on board: an instructor and two pilots gaining night-flying experience. The Cessna, on a private flight, carried a pilot and two passengers and was practicing circuits for night-flying currency.
At approximately 2125 local time, while on final approach to runway 21, the Beech passed over the Cessna. The Cessna pilot reported the vertical separation as approximately 20 feet. The Cessna discontinued its approach and initiated a go-around. Both aircraft subsequently completed normal landings.
Sequence of Events
The Beech began its second session of circuit training at 2108. By 2118, six aircraft were in the circuit area, including the Beech, the Cessna, and four other aircraft operated by Ardmore Flying School. The Cessna turned downwind for its third circuit at 2121, reporting as number 4 in sequence. At 2123, the Beech called on base leg as number 2 to the aircraft on final, intending a touch-and-go. Eighteen seconds later, the Cessna called on final as number 2. At 2124, the Beech called on final for a touch-and-go. Twelve seconds later, the Cessna called that it was going around due to a near-collision on short final. The Beech completed its touch-and-go and continued in the circuit. The Cessna sequenced behind the Beech, and both aircraft landed without further incident.
Contributing Factors
The investigation identified several factors that contributed to the loss of separation. The pilot flying and the instructor in the Beech were unaware of the Cessna's position in the circuit. Although the Cessna's external lighting met regulatory requirements for night flying, the Beech pilots reported difficulty clearly identifying the Cessna. The two aircraft flew different vertical profiles on final approach, increasing the risk of one not seeing the other. A local altitude restriction for Ardmore Airport was published in the operations manual of one operator but not in the Aeronautical Information Publication New Zealand (AIPNZ), which is available to all pilots. Additionally, there were potentially two opportunities for radio transmissions that could have identified the developing conflict.
Personnel and Aircraft
The Cessna pilot held a Commercial Pilot Licence with 256 flying hours. The Beech pilots included an airline pilot with over 21,000 hours (pilot flying) and an instructor with 14,700 hours (pilot in command). The Beech 76 Duchess is a twin-engined low-wing monoplane; the Cessna 172 is a single-engined high-wing aeroplane.
Meteorological and Aerodrome Conditions
The weather was fine and clear, with good visibility, no cloud, and a light south-westerly wind. Ardmore Airport is a general aviation aerodrome with no air traffic control service, but a UNICOM service provides limited traffic information during daytime hours only.
Investigation Findings
The investigation concluded that the Beech pilots' lack of awareness of the Cessna's proximity was central. The difficulty in visually identifying the Cessna at night and the different vertical profiles flown were contributing elements. The local altitude restriction not being available in the AIPNZ also contributed.