A Delta Air Lines flight has apparently been hit by a high-flying firework in the sky above Chicago as the city celebrated the US Fourth of July holiday.

The pilot of Delta flight 1076 notified air traffic controllers just before landing at Chicago Midway International Airport on Saturday night (local time) that a firework hit the commercial plane as it was descending.

In an audio recording published online by LiveATC.net, the pilot described feeling “a big bang” on the plane.

“We just had a firework hit our plane,” the pilot told controllers.

“We’re just hoping it was just a mortar that went off underneath, but definitely felt a big bang.”

The “mortar” is the tube that helps launch aerial fireworks.

According to the recording, the incident occurred when the plane was at an altitude of 60-75 metres. Smaller consumer fireworks can often get to 60 metres in the air, with fireworks from some professional shows getting as high as 350 metres.

Both the US Federal Aviation Administration and Delta said the plane, which had taken off from Atlanta carrying 52 passengers and six crew members, landed safely just after 8.30pm.

The incident did not result in any onboard injuries and Delta said on Sunday that mechanics who inspected the Airbus A319 had found no damage.

The FAA said it would investigate the incident.

It’s unclear if fireworks struck other airplanes on Saturday.

In the LiveATC.net audio, an air traffic controller was heard saying there had been “multiple reports” of such encounters and that Chicago city officials were aware.

As a later Southwest Airlines flight descended into Chicago, a controller warned: “Welcome to the war zone.”

“That’s reassuring,” Southwest 223 responded.

-with AAP