Distress at 18,000 feet An air traffic control tower suddenly lost communication with a small twin engine aircraft. Moments later the tower land line rang which was answered by one of the employees. A passenger riding with the pilot who lost communications was on a cellular phone he yelled ""Mayday, mayday!! The pilot has had an instant and fatal heart attack. I have grabbed his cell phone out of his pocket and he had told me before we took off he had the tower on his speed dial memory. ""I am f…