“The transmitter was accidentally put on the wrong frequency,” said American Airlines spokeswoman Andrea Huguely. “The regular frequency and the frequency for a hijacking are right next to one another, and the transponder was placed on the wrong frequency,” Huguely told CNN.

The mishap caused a complicated security plan to kick in, as law enforcement personnel responded to what they thought was an in-flight hijacking. Two fighter jets were scrambled from Homestead Air Reserve Base, and police and fire-rescue units flooded the tarmac.