A firework mortar slammed into a Delta Airlines passenger jet on final approach to Chicago's Midway International Airport on the Fourth of July, and authorities have made zero arrests. Someone fired military-grade pyrotechnics into an active commercial flight path — and the system designed to monitor every American's phone call somehow couldn't stop it or find who did it.

Delta Flight 1076, an Airbus A319 arriving from Atlanta, was descending toward Midway just after 8:30 p.m. Saturday when a fireworks mortar struck the aircraft. "Tower, we just had a firework hit our plane, Delta 1076, we're continuing," the crew told Air Traffic Control, according to radio traffic obtained by the New York Post. The crew was rattled: "We just heard a bang on the plane … We're just hoping it was just a mortar that went off underneath, but definitely felt a big bang."

The plane landed safely and taxied to the gate. Chicago police said the firework caused minor paint damage, and Delta confirmed the aircraft was undergoing inspection Sunday. No injuries were reported.

And then — nothing. Chicago police referred all further questions to the FBI, according to CBS News. No suspect. No arrest. No indication that the federal government has any lead on who launched a mortar into the flight path of a commercial airliner carrying American passengers.

The New York Post covered the incident as straight news. CBS News likewise reported the facts cleanly but buried the real implication: this is a catastrophic failure of civic order. Both outlets noted the paint damage and the crew's alarm, but neither pressed the obvious question — how does someone fire a fireworks mortar high enough and accurately enough to hit a descending airliner, in a major American city, under what is supposed to be some of the most heavily monitored airspace in the country, and simply walk away?

The federal government spends billions surveilling American citizens — tracking purchases, monitoring social media, hoovering metadata — but it cannot police the airspace around one of the nation's busiest airports on a holiday known for pyrotechnics. The FBI, which has plenty of resources for investigating parents at school board meetings, has apparently produced nothing on whoever fired a mortar at a Delta jet.

This isn't a quirky holiday anecdote. A commercial aircraft was struck by an airborne projectile on approach to a major airport. The fact that it was a firework and not a missile is luck, not policy. Next time, the projectile might not be a mortar shell packed with colored gunpowder. The surveillance state that watches everything still can't enforce the most basic public-safety laws on the ground. That's the open question nobody in authority wants to answer.