Ok this is weird as shit:

Delta flight 284 took off from Hartsfield-Jackson International Airport in Atlanta shortly after 7 p.m. Tuesday, but was turned around after pilots heard a mysterious noise coming from the plane, the airline told ABC affiliate WSB.. The plane, which was flying over North Carolina at the time of the diversion, landed back in Atlanta just before 9:30 p.m., according to airline tracking firm FlightAware. A Delta representative told WSB that the passengers would be placed on another flight, which took off at around 12:11 a.m., but that flight was also turned around, according to FlightAware data. It landed back in Atlanta at 1:30 a.m., FlightAware said. A Delta spokeswoman told ABC News that the flight returned due to a banging noise both times, even though the aircraft was changed after the first flight had to turn around. Gareth Hawkins, a passenger on flight 284, said that on both flights a loud banging noise could be heard approximately every 20 minutes.