The airframer revealed a revised specification for its largest A350 variant at the Paris air show, which will result in a two-year delay.
It centres on a modified, more powerful variant of the Trent XWB engine, along with increased weights.
The move sparked an angry response from A350-1000 launch customer Qatar Airways, with chief executive Akbar Al Baker expressing his displeasure during the show.
While Airbus’s official line was the revisions had been introduced to boost payload and range, industry sources have speculated there may also have been a need to address weight or performance issues that had emerged with the original design.
Clark said the revisions were implemented without any dialogue: “If they had talked to me, I would have said: ‘[The improvement is] not good enough’,” he added.
Although Emirates has only 20 A350-1000s on order, it had been considering switching its 50 -900 orders to the -1000. However, this is unlikely following the revisions.
“On paper, the old -1000 was hugely economical – it was a 777-300 classic replacement,” Clark said. “That’s why I talked about converting my -900 orders.” He added the decision to revamp the A350-1000’s engine by incorporating a new core has had an impact on commonality. “I had 70 aircraft with the same engine. I don’t have that any more,” he said.