Japan's Civil Aviation Bureau said on Friday that preparations are not yet complete for any test flight of Boeing's grounded 787 Dreamliner this week.
"It's Thursday (in the United States) and nothing has been set," said Shigeru Takano, a senior safety official at the Civil Aviation Bureau (CAB). "There are a number of steps it needs to take before a test flight," he told a news briefing.
Boeing plans to conduct two flight tests of its revamped 787 battery system, as soon as the end of the week, three sources familiar with the matter said on Wednesday. The aircraft maker has predicted the 787 could return to operation within weeks.
Japan's aviation regulator last week criticized as inappropriate remarks made by Boeing executives at a March 15 press briefing in Tokyo who said that the cause of the battery fault may never be found. CAB also said it was too early to estimate that the 787 would return to operation within weeks.
The National Transportation Safety Board (NTSB) in the US said Boeing did not inform investigators of what it planned to say about the 787 during last week's briefing in Tokyo, Bloomberg reported on Thursday.
Boeing's position was "inconsistent with our expectations" from a company involved in an accident probe, National Transportation Safety Board (NTSB) general counsel David Tochen wrote in a letter, according to Bloomberg.
"We have received the correspondence, and remain fully committed to support the NTSB and other regulatory authorities in their investigations into the cause of the 787 battery incidents, and also continue our around-the-clock efforts to return the 787 fleet to service," Boeing spokesman Marc Birtel said.