Boeing faces confidence test after Japanese move The decision by Japan's All Nippon Airways and Japan Airlines - the two biggest single operators of Boeing's 787 Dreamliner - to ground their fleets marks a significant worsening of the crisis over the safety of the world's most technologically advanced aircraft. Whatever the ultimate reason for the emergency landing of an ANA 787 jet on Wednesday morning in Takamatsu, western Japan, the carriers" move suggests that two of the staunchest supporters of the revolutionary aircraft could be starting to lose confidence in it. Dreamliners have suffered a series of safety-related scares over the last 10 days. In the latest, an ANA-operated Dreamliner made an emergency landing less than an hour after take-off after instruments in the cockpit indicated a battery malfunction and the pilot noticed a strange smell. ANA subsequently said it would ground all 17 of its Dreamliner jets, while JAL said it was suspending its 787 flights from Japan, citing safety concerns The latest incident is all the more serious because it appears to involve the same issue - the lithium-ion battery that powers many of the aircraft's systems - as in the first and most serious of the safety scares on January 7 in the US. An explosion involving a lithium-ion battery is believed to have been the cause of that fire in the electrical systems of a Boeing 787 at Boston's Logan airport. There are conflicting accounts of whether there was smoke in the cabin when the ANA Dreamliner made its emergency landing on Wednesday, as NHK, the Japanese state broadcaster, reported. However, different accounts appear to agree that the pilot aborted the flight out of concern over the state of the battery. The battery is a concern partly because of the obvious risks of a mid-air fire. The US Federal Aviation Administration released sobering pictures after the January 7 incident showing one of its investigators picking through badly charred material on the floor near where the battery caught fire. The battery is also one of many pieces of novel technology on the Dreamliner. As part of efforts to reduce the weight of the aircraft, Boeing replaced many parts traditionally operated by hydraulics with electrically powered systems. To provide the substantial power required, it opted for lithium-ion batteries over traditional - and heavier - nickel-based batteries. A fire in 2010 during a test flight added substantially to the delays in introducing the 787 into service, but Boeing insisted after the January 7 incident in Boston that nothing suggested the two fires involved related areas or problems. In spite of the recent incidents, there is still considerable confidence among those familiar with the 787 programme that the scares will turn out to have been no more than relatively minor teething problems. Such incidents are not unusual in the introduction of a revolutionary aircraft design. Airbus's A380 superjumbo, the other groundbreaking aircraft currently entering service, suffered a still more serious safety scare in November 2010 shortly after being introduced. In that incident, an engine explosion on a Qantas A380 burst through the casing and damaged a wing. Alan Mulally, who was Boeing's chief executive when the 787 programme was launched and is now chief executive of Ford Motor, faced questions on Tuesday at the Detroit auto show about whether he would fly in one of the aircraft. Speaking before news of the latest scare, he answered unhesitatingly, "Absolutely, yes." However, Wednesday's withdrawal of the two Japanese operators" 787s from service is likely to increase the pressure on both Boeing and the regulators investigating the incidents to come up quickly with explanations for what went wrong. Should there prove to be fundamental design flaws, it will be up to Boeing to provide a comprehensive and reassuring solution before further damage to the programme's reputation is done.