The National Transportation Safety Board (NTSB) has released its preliminary report on the Frontier A321neo incident that occurred in San Juan, Puerto Rico, on April 15. Flight 3506, operating from Orlando, experienced a hard landing that resulted in landing gear damage and engine issues during a go-around attempt.

According to the agency’s initial findings, the incident occurred in the evening when the A321neo – registered as N607FR – attempted to land at Luis Munoz Marin International Airport. The first officer was the pilot flying with the captain serving as pilot monitoring during the night approach.

The approach was reported as stable, though it required a slight lateral correction to maintain centerline while descending through approximately 150 to 100 feet above ground level, the report stated. As the aircraft descended to about 15 feet, the captain noted the jet was too high, prompting the first officer to initiate a correction with a shallow descent followed by a gradual flare.

“The FO recalled that during the approach, she brought the thrust levers back to idle at 20 ft RA while the RETARD aural alert sounded,” investigators shared.

As the aircraft was about to touch down, the captain called for a go-around and took control, believing the “aircraft was running out of flying speed quickly, as the throttles were retarded and the pitch attitude was increasing.”

The airplane subsequently touched down firmly, with flight data recorder information showing a maximum recorded vertical acceleration of approximately 2.2g — exceeding the hard landing threshold of 1.8g specified in Frontier’s aircraft maintenance manual.

Initial Findings

The NTSB investigation revealed that during the go-around attempt, the crew heard a loud bang from beneath the fuselage, and the first officer noted an engine failure displayed on the electronic centralized aircraft monitor. While the air traffic control tower reported an engine fire, the flight crew indicated they only received an engine failure warning.

Post-incident inspection showed the nose landing gear’s left wheel and tire had separated from its axle during the initial hard landing. The report stated that one of the wheel halves had fractured, and numerous scratches and gouges were found on the nose landing gear, along with damage to the tow fitting.

Metal fragments from the wheel assembly appear to have been ingested by the No. 1 (left) engine, causing damage to the engine’s inlet cowl liner, thrust reverser, fan blades, and guide vanes. The left inboard trailing edge flaps were also damaged, though the NTSB noted that none of this damage met the definition of “substantial” or affected the aircraft’s flight control system.

After the initial touchdown and go-around, the flight crew performed a low pass by the control tower to confirm the landing gear status before successfully landing on runway 8. The 235 passengers and crew were evacuated via airstairs with no reported injuries.

In its report, the NTSB noted that in January 2021, Airbus published an article titled “A Focus on the Landing Flare” in their Safety First magazine, which analyzed operational pitfalls and best practices during the landing flare phase — potentially relevant to the investigation of this incident.

Weather conditions at the time of the incident were reported as visual meteorological conditions with few clouds at 2,500 feet, visibility of 10 miles, and light winds at 3 knots from 100 degrees.

The aircraft remains out of service at the time of writing.