Flight AA-672 | Registration: N907AN
Date: 6 April 2025 | Location: Enroute Near Cincinnati/Northern Kentucky International Airport (KCVG), USA
Flight Details
• Aircraft Type: Boeing 737-823
• Engines: 2 × CFM56-7B26
• Operator: American Airlines
• Registration: N907AN
• Flight Number: AA-672
• Callsign: AAL672
• Route: Dallas Fort Worth (KDFW) to New York LaGuardia (KLGA), USA
• Date of Incident: 6 April 2025
• Total Occupants: 166 (159 passengers, 7 crew)
• Weather Conditions: VMC, no adverse weather reported in Cincinnati sector
Introduction
On 6 April 2025, an American Airlines Boeing 737-800 operating flight AA-672 from Dallas Fort Worth to New York LaGuardia diverted to Cincinnati/Northern Kentucky Airport after experiencing a malfunction in the right-hand engine while cruising at FL370. The crew subsequently shut down the engine during descent and safely landed on runway 36R approximately 45 minutes after the initial fault. Rogue radio transmissions on tower frequency complicated the final approach phase, though no flight crew deviated from official instructions. No injuries were reported.
Sequence of Events
Flight AA-672 was cruising uneventfully at FL370 when the flight crew noticed abnormal indications on the right engine (No. 2 CFM56). Engine parameters such as oil pressure, EGT, or vibration likely showed anomalies triggering cockpit alerts. The crew coordinated with ATC and elected to divert to Cincinnati, the nearest suitable airport.
As the aircraft descended toward KCVG, the fault condition deteriorated, leading the flight crew to shut down the right engine in flight. The descent and approach were executed on a single-engine profile, with the crew managing aircraft systems and speed accordingly.
Complicating the approach, Cincinnati Tower’s frequency was affected by unauthorised rogue transmissions issuing false instructions to aircraft, including calls to go around. Tower personnel promptly alerted all aircraft to disregard any unexpected instructions and verify all clearances directly.
Despite this interference, AA-672 continued its approach and landed safely on runway 36R. The aircraft came to a complete stop on the runway for inspection before taxiing to the gate under escort.
Crew & Communication
The flight crew managed the engine fault and single-engine descent with textbook execution. The shutdown was completed following QRH (Quick Reference Handbook) procedures, including:
• Thrust lever retardation
• Engine master switch shutdown
• Fuel cutoff
• Engine anti-ice and crossfeed management
The rogue radio transmissions did not lead to confusion on board AA-672 due to clear tower directives and crew vigilance. The flight crew confirmed instructions verbally with ATC to ensure safety and situational awareness during the approach phase.
Cabin crew were informed and prepared the cabin for a precautionary landing, and communication with passengers was clear throughout.
Aircraft Systems & Technical Analysis
The CFM56-7B26 is a highly reliable powerplant, but in-flight shutdowns still occur due to:
• Oil pressure loss
• Oil system leaks
• Vibrations exceeding limits
• Internal mechanical failure (e.g., bearing or gearbox issues)
• Sensor or FADEC (Full Authority Digital Engine Control) anomalies
A post-flight inspection revealed evidence of an internal oil leak and a suspected loose engine component, according to a report from the fire chief who boarded the aircraft after arrival. These findings suggest the issue may have involved:
• A failed oil pump seal or gasket
• Loose oil lines
• Damaged accessory gearbox or starter motor component
American Airlines’ maintenance team would have conducted borescope inspection of the right engine, oil sample testing, and retrieval of maintenance message history through the Central Maintenance Computer (CMC).
Given the decision to ground the aircraft and dispatch a replacement, a full engine teardown or removal may be warranted.
Passenger Experience & Cabin Conditions
A passenger on board stated that the engine was shut down approximately 15 minutes prior to landing. Oxygen masks were not deployed, and there was no sudden descent, cabin depressurisation, or visible fire or smoke.
Passengers experienced a smooth but precautionary landing followed by a brief runway stop for inspection. Fire crews met the aircraft and conducted an initial assessment before the aircraft continued to the gate.
Cabin crew maintained control throughout the event, and no injuries or panic were reported.
Emergency Response & Aftermath
Cincinnati Airport Fire and Rescue units were deployed to meet the aircraft on landing. Visual and infrared inspections were likely performed to check for external oil leaks or hot spots on the shut-down engine.
Once cleared, the aircraft taxied to the gate, where the fire chief boarded and informed the crew of findings including a possible oil leak and an unsecured internal component.
N907AN was removed from service for a detailed technical evaluation. A replacement Boeing 737-800, registration N915AN, was dispatched to complete the journey to LaGuardia. Passengers reached their destination with a delay of approximately 5.5 hours.
Investigation Status
The Federal Aviation Administration (FAA) has acknowledged the event and will conduct a mechanical failure investigation, including review of:
• Engine health monitoring data
• In-flight shutdown procedures
• Maintenance history of the No. 2 engine
• Whether the rogue transmissions posed additional risk during approach
The nature of the unauthorised radio activity is also being reviewed by federal communications authorities, as this may constitute a breach of aviation security regulations.
No NTSB investigation has been initiated as the event did not result in damage or injuries, but final findings may still be documented for safety monitoring purposes.
Root Cause & Contributing Factors
Preliminary indications suggest the shutdown was due to:
• Internal oil system failure or leakage
• Possible mechanical component looseness inside the engine
• Elevated vibration or oil temperature prompting a precautionary shutdown
Contributing factors may include:
• Wear or degradation of engine seals
• Maintenance deferral of oil system components
• Long sector cruise profile exposing the issue at higher altitudes
The crew’s prompt response and decision to shut the engine down mid-descent minimised the risk of secondary damage or loss of performance.
Safety Recommendations & Industry Impact
This incident underlines the importance of:
• Real-time engine monitoring systems for early fault detection
• Crew adherence to single-engine landing procedures
• Airport readiness for unplanned diversions involving engine shutdowns
• Strict radio frequency security and pilot awareness of unauthorised ATC impersonation
American Airlines may issue internal advisories regarding oil system inspection intervals, and Boeing or CFM could release technical notes if component failure is confirmed.
Airspace regulators are also expected to review air traffic radio security following the rogue transmission interference near KCVG.
Conclusion
American Airlines flight AA-672’s diversion to Cincinnati following an in-flight engine shutdown highlights the effectiveness of modern crew training, robust engine monitoring, and emergency preparedness. The situation was handled calmly and efficiently, with a safe landing and minimal disruption.
The event also brings attention to secondary threats like radio frequency interference, which—though rare—can create operational confusion during critical phases of flight.
Disclaimer
This article is based on publicly available information and reports at the time of writing. While every effort has been made to ensure accuracy, we cannot guarantee the completeness of the information provided.
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