Incident Overview
On 12 February 2019 at 1900 UTC, a serious incident occurred at London Stansted Airport involving an Airbus A320 (registration OE-IHD) and a Saab-Scania 340B (registration G-LGNK). Both aircraft were conducting commercial passenger flights. No injuries were reported, and neither aircraft sustained damage.
History of G-LGNK
G-LGNK, a Saab 340, was departing from Stansted to Dundee. The crew was cleared for the UTAVA 1R Standard Instrument Departure (SID) with an initial altitude of 4,000 ft. After reporting ready at holding point R1 for Runway 22, they were cleared for immediate takeoff. As the aircraft passed approximately 1,000 ft, ATC advised that an aircraft on approach had initiated a go-around. The crew was instructed to continue the SID but shortly after were directed to turn right onto a heading of 290°. The commander, with the autopilot engaged, initiated the turn. A subsequent instruction to "stop climb at altitude 3,000 ft" was acknowledged by the co-pilot. Passing approximately 2,500 ft, the aircraft's TCAS issued an audio Traffic Advisory (TA), followed seconds later by a momentary "level off" Resolution Advisory (RA) at about 2,700 ft. The commander disconnected the autopilot and leveled the aircraft, after which the TCAS issued a "clear of conflict" message. The aircraft then climbed to 3,000 ft. The co-pilot did not transmit the TCAS RA to ATC due to high workload. The flight continued to Dundee, where the crew reported the event to Stansted ATC upon arrival.
History of OE-IHD
OE-IHD, an Airbus A320, was arriving at Stansted. While at approximately 14,000 ft, ATC provided a short-cut and a speed reduction to 250 kt, placing the aircraft above the descent profile. Both pilots noted the situation, but the co-pilot, who was pilot flying (PF), considered the approach acceptable. At 7,000 ft, ATC cleared the aircraft to 2,000 ft, and the crew used speed brakes to increase descent rate. Further speed restrictions to 220 kt and then 200 kt reduced the descent rate. ATC offered to extend the distance to landing, but the co-pilot declined. The commander then directed extension of the landing gear to increase drag. As the aircraft approached the glideslope intercept, the glideslope indication was near the lower limit. The autopilot entered altitude capture mode at 2,000 ft, reducing descent rate again. The commander directed a vertical speed mode, but the co-pilot inadvertently triggered a climb mode. Recognizing the impossibility of a stable approach, the commander ordered a go-around. The co-pilot set TOGA and disconnected the autopilot. The commander set the go-around altitude to 3,000 ft. At 3,000 ft, confusion over speed and flap selections led the co-pilot to reduce thrust to idle. The commander directed "set thrust and Flap 1" and then took control. ATC then instructed a climb to 4,000 ft and a heading of 135°, followed by a turn to 090°. The commander, unable to engage the autopilot due to flight director commands, made manual turns. A "priority right" callout indicated the co-pilot had pressed the priority takeover button. The commander reiterated control, turned left, and climbed to 4,000 ft. The Saab 340 appeared as a TA on TCAS and disappeared during the climb. The commander subsequently flew an uneventful approach and landing.
Human Factors
The A320 crew consisted of a commander under line training (left seat) and a line co-pilot (right seat), supervised by a training captain from the jump seat. The commander, in an unfamiliar role and being assessed, allowed the excess energy situation to persist longer than usual, which contributed to the aircraft being above the glideslope near 2,000 ft. The autopilot's capture of 2,000 ft surprised the co-pilot. Despite the commander's instructions, the co-pilot's actions under pressure triggered a climb. The go-around resulted in significantly elevated workload. The commander took control upon recognizing the co-pilot's reduced situational awareness.
Analysis and Conclusion
The A320 was in a state of excess energy during arrival, recognized by the crew and ATC, who offered extra distance that was declined. The autopilot altitude capture at 2,000 ft suddenly increased workload, leading to the go-around. High workload and a change of pilot flying caused the crew's focus to remain inside the cockpit, delaying their response to ATC instructions. The delayed response resulted in a short-term loss of separation between the two aircraft, with the closest approach recorded as 87 m laterally and 600 ft vertically. The Saab 340 crew received a TCAS Resolution Advisory, which prevented further degradation of separation.