Tests were due to begin today, but an Airport spokesman said they have not commenced yet, as the crew is waiting for rain.
Airport chief executive Steve Sanderson said the trial will show the maximum performance of the runway.
"The visit is part of Airbus' continuous programme of performance tests where the company evaluates aircraft in specific operating environments and conditions."
The A350 has a longer range than the aircraft currently using Wellington, but the airport's shorter runway length constrains the loads and distance of some single aisle jets and all twin aisle jets.
While the testing of the aircraft is not related to the airport's proposed runway extension it will help further inform the existing data for Airbus, said Sanderson.
"The testing will show the different combinations of loads and distance an A350 can reach off Wellington's runway. This trial is about determining future performance for Wellington as more of these aircraft enter the fleet in the Asia-Pacific.
"There is a worldwide trend among airlines to use direct, otherwise known as point-to-point, fuel efficient aircraft with seating capacity matched to demand. This enables efficient, sustainable routes to be opened up to cater for the ever growing demand in air travel, especially in the Asia-Pacific region which is one of the fastest growing in the world."
The conditions for the test are ideal when there is reasonable amount of rain and light winds. Wellington's grooved runway assists the surface water to flow off and improve friction for wheel braking. Wellington's wind in most cases assists aircraft by providing extra resistance on landing and assistance with lift on take-off.
Ideally there is limited wind when the testing is being undertaken.
The results will add to Airbus database of performance in these particular conditions.
