Airbus's roll-out and first flight of the A350-900 prototype will not ease the pressure on the airframer's flagship twinjet programme, but simply give it a different nature.
The first aircraft's entry into the flight-test phase marks only the beginning of a phased certification effort which will require completion of another four A350s.
Airbus's attention is turning increasingly towards the production ramp-up as well as the development of the A350-1000, after a year in which the largest member of the family has attracted orders from several high-profile customers.
But progress on the -900 will not advance the schedule of the -1000, insists A350 programme manager Didier Evrard.
"There is no change here," he says. "We are going step by step. The ramp-up of resources will be very high this year."
Design and technology insertion for the -1000 has been frozen, he says, and specific design work is in progress. The -1000 is due to enter final assembly in the second half of 2015, with the aircraft's first flight set to take place a year later, before entry into service in 2017.
"What was really interesting in the last few months was to see the -1000 orders growing," says Evrard. "The -1000's endorsement is confirmed."
British Airways' decision to select the type as a Boeing 747-400 replacement follows conversions and orders from Cathay Pacific, Qatar Airways and Air Lease, secured after the variant's redesign in 2011.
Evrard says the -1000's development will benefit from the re-use of several major components built for the -900, including the hydraulics, air generation system, wing fuel pumps, integrated avionics, electrics and flight-control equipment.
Airbus parent EADS suggested in May that the -1000 could require the airframer to seek extra assembly capacity, although it has not indicated whether this might best be achieved by efficiency measures at its Toulouse plant or through extending its facilities.
However, the airframer's priority is the production of the A350-900 flight-test fleet. Prototype MSN1, which was rolled out on 13 May, and MSN3 - the second to enter final assembly - will be the primary airframes for flight-control testing, both heavily instrumented for the purpose.
MSN1 carries a flight engineer test station, 8.4t of acquisition racks and some 338km of harnesses, as well as water ballast tanks to adjust the centre of gravity.
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"It's quite an exercise to install all this on top of what's already in the aircraft," says A350 chief engineer Gordon McConnell. But he adds that the tanks enable water transfer in flight, saving the need to land to alter the aircraft's balance.
MSN1's tasks will include natural icing tests, while MSN3 - due to fly in late September or early October - will undertake the high-altitude campaign, as well as hot and cold performance testing.
The other three prototypes will be introduced to the certification programme over the first four months of 2014. MSN2, flying in January, will be the first fitted with an interior cabin, and will be used for early long flight and initial evacuation assessment.
MSN4 and MSN5, active from February and April next year respectively, will each be lightly equipped with instrumentation. MSN4 will be used for external noise analysis but MSN5 - which, like MSN2, will be cabin-equipped - will conduct the route-proving and extended twin-engined operations (ETOPS) tests.