In Toulouse, it was proving hard to make the business cases stick, but one proposal labelled "1d" looked promising.
It dived deep into a planemaker's armoury of wings, cockpit, cabin, engines and the all-important wider fuselage.
It would cost about 11 billion euros to build rather than the 4 billion budgeted for the original A350, while setting Airbus up for 20 years with projected sales of 2.000 planes instead of 800. But it was still a step behind Boeing's 787: the tube would be in metal rather than carbon.
Meanwhile, an internal crisis cast a new shadow over the proposals.
Delays to the A380 hit share prices in June/2006 and forced Humbert to resign. The Farnborough Airshow was looming and a divided board was not ready to commit to a new project.
"No decision was taken to discontinue the original A350," Andries said. "Most senior executives at the time were against the Extra-Wide Body. Even in the summer of 2006 the decision was not secure."
Airbus nonetheless took the risk of presenting the concept at the July/2006 show. Even as it called the plane a "step ahead of the 787" it made little reference to the metal shell.
Humbert's replacement, aerospace outsider Christian Streiff, took top Airbus managers to a converted French abbey to reflect.
Over dinner, according to a person familiar with the event, he asked them to raise their hands if they thought Airbus should build the very plane they had publicised weeks earlier. Only a handful did, including sales chief John Leahy and Andries.
Nevertheless, the engineers pressed on. Soon, they came up with a cost-effective way to make an all-carbon body assembled from panels, which they felt would be cheaper to build than the single giant piece in the Boeing 787.
In December/2006, the reversal was complete: the board approved the new, all-carbon A350XWB.
The future of the chess game: 777-X versus A350-1100.
Meanwhile, the battle of the air goes on. Whether Airbus can meet Humbert's challenge of 50% wide-body market share depends partly on the success of Boeing's latest move - a larger and upgraded 777, Udvar-Hazy said.
The answer may lie in a drawer in Toulouse. Industry sources say Humbert's planners drew up, but discarded, a variant for a larger version of its new jet called A350-1100. That could provide a clue to Airbus's options next decade.
Based on the article “Flying back on course: the inside story of the new Airbus A350 jet” published in Reuters.