Phil Hammond explores human error in the medical profession. Thousands of patients die each year because doctors and nurses, although technically skilled, are not alert to the risk of a potentially life-threatening mistake. Airline pilot Martin Bromiley, whose wife was a victim of such an error, talks about his experience. Contributors include health minister Lord Darzi, chief medical officer Liam Donaldson and American surgeon Atul Gawande. A Ladbroke Radio production for BBC Radio 4.