An American Airlines plane carrying passengers from Philadelphia to Naples had to make a sudden mid-air diversion after the pilots understood that the Boeing 787-9 that they were flying was not certified to land at Naples Airport; it was too big for the airport. The incident took place on June 2, and the airlines said the diversion to Rome was due to operational reasons. American Airlines Flight AA780 departed Philadelphia at 7:42 PM and crossed the Atlantic without incident. It was supposed to land in Naples at 10 am local time. But as the aircraft began its descent into Naples (NAP), the crew altered course and redirected the flight to Rome Fiumicino Airport, approximately 124 miles away from the destination. The passengers were bused from Rome to Naples which takes two hours. Historical flight data shows that American Airlines usually sends a Boeing 787-8 on flights to Naples. While these two Dreamliner variants are pretty similar, with the same wingspan, the 787-9 is actually 20 feet longer.Flight 780 had to change course over the Tyrrhenian Sea. The 787-8 is small enough to land at an airport with a Category 8 RFFS, but the 787-9 needs a Category 9 RFFS airport. Aviation enthusiast @xJonNYC, who first shared the incident on X, reported that the airport authority said 787-9 planes can’t land in Naples.After landing at Rome Fiumicino Airport around 9:45 a.m., passengers were transported to Naples by bus, the airline spokesperson told Business Insider. “We apologize to them for this disruption to their journey,” they added. The 787-9 departed Rome two-and-a-half hours later, operating Flight 111 to Chicago, per Flightradar24.