A complaint from a passenger aboard a Delta airliner caused the pilot to make an emergency landing at McGhee Tyson Sunday. A spokesperson for Delta said flight 1939 was traveling from Pittsburg to Atlanta when it was diverted to Knoxville the airport around 4:30. Delta told Local 8 News one of the 149 passengers complained that an unusual odor was circulating throughout the cabin. When the landed safely at McGhee Tyson, mechanics examined the plane and determined there was no issue. After further inspection, the plane took off again and landed safely in its initial destination, Atlanta, an hour behind schedule.