There are 387 Boeing 737 Max aircraft currently sitting, idle, on airport tarmac around the world. The Max was grounded by regulators after a defect was found to have caused the Lion Air and Ethiopian Airlines crashes, in which 346 people were killed.  The planes were grounded 10 months ago. At first, the Max was expected to be back flying in no time. But an investigation by the US Federal Aviation Authority uncovered more problems, and Boeing hasn’t been able to resolve the software issue which led to the crashes. Boeing’s stock is down 23 per cent since the planes…