Boston—The head of Dubai airline Emirates piled pressure on planemaker Boeing on Tuesday over delays to its 777X jetliner, warning that the uncertainty would cause significant disruption for one of the world’s biggest carriers. Emirates President Tim Clark said he wanted “another grown-up conversation” with the U.S. planemaker over the timing of the twin-engined jumbo, which is running at least two and a half years behind its originally planned arrival of June 2020. “We work to precision. I struggle with others who can’t get that,” Clark told reporters shortly before he was due to meet Boeing leaders on the sidelines of an airline industry summit. Clark, an airline industry veteran who was closely involved in the development of the current 777-300ER model, has lambasted Boeing this year over repeated delays to its 777X. Boeing had no immediate comment when contacted by Reuters. The company has previously said it plans to …