This aircraft is being operated on lease from US-based CIT.
The plane offers 321 seats in a two-class layout, comprising 32 Royal Silk Class seats, convertible to fully lie-flat beds, and 289 seats in the main cabin.
After an initial period flying on regional services between Bangkok and Chiang Mai, the aircraft will |soon be deployed on long-haul flights, starting with Bangkok-Melbourne.
Four of them are being purchased directly from Airbus and the other eight acquired under leases.
The A350 XWB features the latest aerodynamic design, carbon-fibre fuselage and wings, and new fuel-efficient Rolls-Royce engines.
Airbus says these technologies translate into unrivalled levels of operating efficiency, with a 25-per-cent reduction in fuel burn and emissions, and significantly lower maintenance costs.
The spaciousness, quietness, beautiful interior and mood lighting in the cabin contribute to superior levels of comfort and wellbeing, setting new standards in flight experience for all passengers, it says.
Airbus has logged 810 firm orders for the A350 XWB from 43 customers worldwide, already making it one of the most successful wide-body models ever, the French company says.