An off-duty pilot who was a passenger on a Southwest Airlines flight stepped in to help the flight crew after one of the on-duty pilots had a medical emergency mid-flight. He’s in the back of the aircraft right now with a flight attendant, but we need to get him on an ambulance immediately,” a member of the flight crew is heard saying in air traffic control audio from LiveATC. After safety returning to Las Vegas, a backup crew boarded and the flight continued to Columbus as planned, the airline said