DENVER — United Airlines has cut the grounded Boeing 787 Dreamliner from its flying plans at least until June and postponed new Denver-to-Tokyo flights. Investigators are trying to find what caused a battery fire in one plane and forced the emergency landing of another last month. The world’s 50 787s have been grounded since Jan. 16.

United said the plane could fly earlier than June 5 if a fix is found. United was to begin flying from Denver to Tokyo on March 31. It’s postponing the start of those flights at least until May 12.