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Crashed Asiana A320 drifted below glidepath in low visibility

By: DAVID KAMINSKI-MORROW

Source: 

12:51 13 May 2015

Japanese investigators have indicated that an Asiana Airlines Airbus A320 began to deviate from its descent path shortly after its autopilot was disengaged, before it collided with the localiser antenna atHiroshima.

The A320 had been conducting the area navigation (RNAV) approach to runway 28 on 14 April.

It hit an approach light at a height of 4m before carving through the antenna. Flight OZ162 subsequently veered off the runway, suffering substantial airframe damage.

Preliminary findings by the Japan Transport Safety Board show that weather conditions were not ideal, with light rain and fog reducing visibility on the runway to 300m in places.

The aircraft passed the final approach fix at a height of just above 3,000ft and initially followed the correct descent profile.

Its autopilot was disconnected at around 2,100ft but the inquiry’s data indicates that, after this switch to manual operation, the A320 began to drift below the normal glidepath. Its airspeed stayed largely constant, around 130kt, according to flight-recorder data released by the JTSB.

The glidepath deviation gradually became more pronounced until the aircraft hit the localiser, situated 325m before the runway.

Just 2s before the impact the recorder data indicates an attempted go-around, with changes to the side-stick input and the engine thrust-lever positions.

After destroying the antenna the A320 shed debris before reaching the runway, its aft fuselage making ground contact 148m short and its main gear following at 136m.

It travelled 725m along the runway but then started veering to the left and exited 1,154m from the threshold, coming to rest facing almost in the opposite direction.

Passengers evacuated the aircraft through slides, suffering only minor injuries during the accident.

Asiana had previously disclosed that the aircraft’s captain had accumulated over 8,200h and the first officer nearly 1,600h.

Investigators have yet to determine the primary cause and contributing elements to the event.