On August 27, 2006, Comair Flight 5191, a Bombardier CL-600-2B19, crashed during takeoff from the wrong runway of Blue Grass Airport, Lexington, Kentucky, killing 49 of the 50 people aboard. From the beginning everything went wrong. First the captain and first officer boarded the wrong airplane, only after starting the auxiliary power unit they found out they were in the wrong aircraft. Taxiing to the takeoff position the captain and first officer were so deeply engaged in a private conversation that they did not realize they took the wrong runway. The air traffic controller did not notice anything.