How often medical events occur in flight remains largely a secret to the public because the Federal Aviation Administration doesn t require airlines to report them. But the NBC Bay Area Investigative Unit discovered that medical emergencies may be happening more often than anyone knows. And now some doctors are putting pressure on the airline industry to make the data public. Elyse Kirchner reports. This story was first broadcast on Nov. 20, 2012 at 11 p.m.