The ticking clock has once again got the better of Boeing. The company announced on Tuesday that, for the fifth time, its flagship new aircraft will not be taking to the air on schedule. The discovery of an area of structural weakness means that it will be several weeks before a new plan for flight tests can be set. There is now a significant chance that the entire Dreamliner programme becomes a commercial disaster.

The previous delay was related to fastners, compounded by last year’s machinists strike. With perhaps 4m parts on the modern airliner, even small problems in one area can then impact on other parts. For instance, earlier this decade BAE Systems discovered a initially small problem in the Nimrod military aircraft, which ultimately resulted in great delays and catastrophic cost overruns. The latest postponement at least suggests that Boeing’s very short timetable for testing and certification is too aggressive.