An American Airlines flight turned into a midair nightmare Sunday when a deranged passenger allegedly bit a fellow flier as the plane descended over Philadelphia.

Frantic radio transmissions from the pilot revealed that an onboard traveler had become dangerously aggressive, CBS said.

“He’s trying to fight everybody,” the pilot said as he requested police and emergency medical teams to meet the aircraft upon landing.

The flight had departed from Charlotte, NC, and was nearing Philadelphia when the chaos erupted.

The pilot suggested the incident was sparked by a mental-health episode.

“I don’t know … if he’s hallucinating or whatever, but he just bit a passenger, and he’s trying to fight everybody,” the pilot said to a controller in that audio recording.

The bizarre incident is the latest in a string of shocking passenger disturbances that have made headlines in recent weeks.

Earlier this month, a passenger bit a cop who was trying to remove her from a plane when she refused to pay an excess-baggage fee.

In another recent incident, a Frontier flight from Puerto Rico to Chicago made an emergency landing in Miami — with wild video capturing the moment an out-of-control passenger tried to pry open exit doors and break into the pilot’s cabin mid-flight.