Aviation regulators worldwide laid down a stark challenge for Boeing to prove that its grounded 737 Max jets are safe to fly amid suspicions that faulty software might have contributed to two crashes that killed 346 people in less than six months. In a key step toward unearthing the cause of the Ethiopian Airlines crash, flight recorders from the shattered plane arrived Thursday in France for analysis, although the agency in charge of the review said it was unclear whether the data could be retrieved. The decision to send the recorders to France was seen as a rebuke to the United States, which held out longer than most other countries in grounding the jets. Boeing executives announced that they had paused delivery of the Max, although the company planned to continue building the jets while it weighs the effect of the grounding on production.
