Wizz Air Abu Dhabi A6-WZG

Arrival from Baku

On 29 April 2023, Wizz Air Abu Dhabi flight WAZ25GR departed Heydar Aliyev International Airport in Baku for Abu Dhabi. The Airbus A321-271NX, registered A6-WZG, carried 208 passengers, two pilots and five cabin crewmembers. The copilot was flying; the commander was monitoring. Takeoff from runway 17 was at 06:15 UTC. The aircraft climbed to flight level 350 and later cruised briefly at flight level 270 before beginning its descent at 08:20.

The crew established the aircraft on the instrument landing system approach to runway 31L. At 08:40:30, the tower cleared it to land and gave a surface wind of 300 degrees at 11 knots. The landing gear was lowered, the spoilers armed and full landing flaps selected. Managed approach speed was set to 137 knots. The pilots disconnected both autopilots at 08:43:54, at 540 feet radio altitude, and continued manually. The AAIS found the aircraft airworthy at dispatch and the flight crew qualified for the flight.

Wind changes during the flare

The approach remained on profile apart from a brief excursion about 20 feet below the glideslope at 300 feet radio altitude. Near the threshold, recorder data showed fluctuating airspeed and vertical acceleration consistent with the thermals described by the commander. From 70 feet radio altitude to touchdown, wind direction varied between 305 and 248 degrees and speed between 6 and 20 knots. The peak crosswind component reached approximately 17 knots during the initial flare.

The aircraft crossed the threshold at about 25 feet radio altitude at 08:44:37. The copilot made rudder and sidestick corrections as its heading, bank and drift changed. At 08:44:39, three automatic retard callouts sounded and the thrust levers moved to idle, disconnecting autothrust. The commander made his own retard callout at the same time. He later recalled hearing the 40-foot height callout but could not recall the remaining height calls. The AAIS found that his attention to the aircraft's alignment affected his monitoring of these cues.

Touchdown went unrecognized

The left main gear touched down first at 08:44:43, followed about half a second later by the right main gear. The touchdown was smooth, at approximately 135 knots and eight metres right of the runway centreline. The right gear contacted the runway about 430 metres beyond the threshold, within the touchdown zone. The main gear remained on the runway for roughly 17 seconds, while the nosewheel stayed airborne. Ground spoilers deployed and the aircraft began losing speed.

Both pilots continued to believe that the aircraft was airborne. The copilot made successive rudder corrections as drift changed direction. Investigators considered those inputs slightly disproportionate, contributing to heading and drift fluctuations. About one second after touchdown, the thrust levers moved from idle to maximum reverse and then to reverse idle. Neither pilot recognized the reverse selection. The copilot later said he had never touched down or selected reverse. The AAIS found that his intense focus on alignment probably affected his awareness of touchdown and lever movement.

The recorder showed the right engine reverser deploying for about two seconds and the left for about one second. The idle detent normally prevents movement into reverse during flight and can be overridden on the ground. Investigators considered it possible that the copilot inadvertently used the levers to steady himself during the changing lateral accelerations. They described that physical explanation as a possibility. The movement into reverse was recorded directly.

Two go-around decisions and an unclear handover

At 08:44:49, the copilot advanced the thrust levers towards TOGA, the takeoff and go-around position. He believed the aircraft was still airborne and was concerned about its position along the runway. The commander began using his own sidestick while the copilot was still making inputs. The first TOGA selection started retracting the spoilers and increasing engine speed. The commander then pulled the thrust levers back to idle because he intended to continue the landing. The spoilers began deploying again.

The required go-around and control-transfer announcements were omitted. The commander took control without the standard declaration, and the copilot did not acknowledge the handover. At about 08:44:53, the commander reversed his decision and began advancing the levers to TOGA. The copilot asked whether they were on the ground. The commander believed the aircraft had excess energy and assumed its speed remained similar to its threshold speed. Investigators found that he had not checked the actual airspeed. The recorded speed fell to a minimum of 108 knots at 08:44:55.

Pitch exceeded the available tail clearance

Simultaneous sidestick inputs continued for about seven seconds, from 08:44:49 to 08:44:56. The A321 added the two pilots' commands algebraically, with the combined command limited to the equivalent of one fully deflected sidestick. When the dual-input warning sounded, the copilot released his stick. The commander called for a go-around at 08:44:57. At that moment pitch was increasing through approximately 9.8 degrees and airspeed was about 111 knots.

TOGA selection retracted the spoilers and deactivated the landing tail strike protection. That protection had previously limited the pitch response despite nose-up commands. With it deactivated, sustained nose-up input and the pitching effect of increasing thrust raised the nose rapidly. The AAIS estimated that tail contact began when pitch reached the 9.7 degree limit while the main gear was still compressed. Contact lasted about three seconds. At 08:45:00, the aircraft lifted off at 118 knots and a maximum pitch of 10.81 degrees. A configuration warning sounded because the flaps and slats remained fully extended.

Climb, warning and return

The go-around continued, but the pilots' duties remained confused. The commander made the positive-climb call normally assigned to the monitoring pilot. The copilot called for gear retraction, normally commanded by the flying pilot. Landing gear retraction occurred before the flaps were moved from full to position 3. The AAIS calculated a 28-second delay between the commander's go-around announcement and that flap selection. It found that the coordination problems had continued into the climb.

At 08:45:38, the crew of another aircraft, GFA543, reported a possible tail strike to ground control. WAZ25GR's crew initially told controllers that they had gone around because of an unstable approach. At 08:55:22, GFA543 contacted them directly and explained that the tail had looked very close to the runway, although its crew was uncertain about contact. The commander checked pressurization and found a normal indication. WAZ25GR completed another ILS approach to runway 31L and landed uneventfully at 09:02:55. No occupant was injured. Inspection found abrasion on the aft lower fuselage between frames 65 and 67 and stringers 42L and 42R. The drain mast assembly required replacement before the next flight.

The investigation findings

The aircraft carried two combined cockpit voice and data recorders. Investigators successfully downloaded both the cockpit audio and flight data and also received quick access recorder data. They synchronized the recorder evidence with air traffic control communications. That evidence established main-gear contact, the reverse selections and the overlapping sidestick inputs, despite the pilots' recollections that touchdown had not occurred. The duration of tail contact was estimated from pitch, landing gear state and the aircraft's ground clearance geometry.

The AAIS concluded that improper high pitch control during initiation of a go-around at low airspeed caused the tail strike. It identified gusty landing conditions, missed height and retard callouts, unnoticed idle and reverse selections, slightly excessive rudder inputs and unclear communication as contributing factors. The commander's mistaken belief that the aircraft had excess energy also contributed. Investigators assessed the pilots' attention and awareness using the recorder data, their statements and the sequence of control movements.

The aircraft's tail strike protections operated according to their design. Go-around mode gives the crew full pitch authority so that a required avoidance manoeuvre can be flown. The pitch warning is also inhibited during that phase. The operating manuals required a full-stop landing once reverse thrust had been selected. Existing simulator exercises included rejected landings below 100 feet while airborne, but did not specifically address a go-around after touchdown. The AAIS accepted Airbus's explanation that a prescribed technique for that situation could encourage departures from the normal landing procedure.

The manufacturer explained that an immediate collision threat after touchdown could require a go-around, but that the circumstances could be difficult to distinguish in advance. The AAIS agreed that safety in such an emergency depended on the crew's awareness, basic skills and airmanship. Its analysis found that awareness and airmanship had degraded during this landing. The manuals also cautioned against excessive rotation rate when a go-around was flown near the ground.

Training actions and three recommendations

The final report recorded remedial simulator training and subsequent line checks for both pilots. The commander received further training in command duties, assertiveness and taking over control during low-altitude, low-energy balked landings, followed by four supervised sectors. The copilot practised crosswind landings and correction after an off-centre touchdown, followed by ten supervised sectors. Wizz Air Abu Dhabi added a policy about rostering new pilots together and circulated safety material stressing standard callouts, timely intervention and the requirement to complete a landing after reverse selection.

Airbus issued training recommendations for go-arounds at very low height, addressing the risk of excessive pitch and tail contact. The AAIS issued three recommendations to Wizz Air Abu Dhabi. SR11/2024 called for training in low-energy rejected landings close to the ground, including simulator practice. SR12/2024 called for renewed emphasis on the monitoring role and its callouts. SR13/2024 called for reinforcement of crew resource management requirements and identification of CRM issues during pilot checks. The AAIS issued its final report on 6 August 2024.