Flight Details
Aircraft Type: Boeing 747-412F (Freighter) Operator: Sky Lease Cargo Registration: N904AR Flight Number: GG4550 Route: Arturo Merino Benítez International Airport (SCL), Santiago, Chile to Miami International Airport (MIA), Florida, USA Date of Incident: 19 April 2025 Total Occupants: Not specified; standard freighter crew typically 2–4 flight crew, possibly additional loadmasters or engineers Weather Conditions: No adverse meteorological conditions reported at the time
Introduction
On 19 April 2025, a Sky Lease Cargo Boeing 747-400 freighter was forced to reject takeoff at high speed—approximately 160 knots over ground—from Santiago’s runway 17R following an unspecified engine problem. Although the crew managed to bring the aircraft to a safe stop, the extended high-speed deceleration caused thermal overload and deflation of all 16 main and body landing gear tyres. The aircraft vacated the runway at the final exit and came to a full stop on a parallel taxiway. Airport emergency services responded immediately, and the aircraft remains grounded at Santiago as of 23 April 2025.
Sequence of Events
Flight GG4550 was performing a standard cargo sector from Santiago to Miami. The Boeing 747-400F had received departure clearance and began its takeoff roll on runway 17R. During the high-speed acceleration phase, at approximately 160 knots, the crew detected an unspecified engine anomaly, likely involving one of the four General Electric CF6 engines.
The decision to reject a takeoff above 100 knots is a critical and rarely executed procedure, reserved for engine failure, fire warning, or severe system malfunctions. The takeoff was aborted rapidly, with the crew deploying full braking systems and potentially reverse thrust on operative engines.
As the aircraft decelerated along the runway, the energy load transmitted to the main and body landing gear tyres became excessive. The aircraft exited at the final taxiway but stopped soon after due to complete deflation of all 16 tyres—an expected outcome when carbon brakes and anti-skid systems generate excessive thermal energy during RTO (Rejected Take-Off) deceleration at or above V1 speeds.
The aircraft was immobilised on the taxiway, requiring recovery assistance and technical inspection.
Crew & Communication
The flight crew’s response was immediate and followed Boeing’s RTO guidelines:
Detection of abnormal engine behaviour at takeoff thrust RTO decision made prior to reaching VR (rotation speed) Full application of autobrakes or manual max braking Spoiler deployment and thrust reverser engagement Notification to ATC and coordination for emergency services response
Although the crew did not declare a Mayday, the nature of the rejected takeoff and subsequent immobilisation triggered a Level 2 airport emergency response at Arturo Merino Benítez International.
There are no reports of crew injuries or fire detection onboard.
Aircraft Systems & Technical Analysis
The Boeing 747-400F in question is powered by four General Electric CF6-80C2B1F engines. The problem that triggered the RTO has not yet been publicly confirmed, but common causes include:
Engine surge or stall during acceleration Fire warning or abnormal EGT rise Vibration exceedance from compressor blade damage Engine instrumentation failure (N1/N2 overspeed, oil pressure drop) Bird ingestion or foreign object debris (FOD)
Rejected takeoffs at high speed produce immense braking loads. Tyres are designed to absorb this via thermal plugs, which melt and deflate tyres in a controlled manner to avoid tyre explosion. The 747-400 has:
Four main gear assemblies (two wing, two body) Sixteen wheels in total (4 per gear set) Carbon brakes with anti-skid and brake temperature monitoring
In this case, the entire set of tyres deflated, indicating that the braking effort approached or exceeded energy design thresholds, particularly under maximum takeoff weight (MTOW) conditions on a long-haul cargo flight.
Post-incident actions include:
Tyre and brake unit replacement Wheel and axle inspection for heat damage Borescope inspection of affected engine FDR and maintenance log data extraction
The aircraft remained disabled on the taxiway for a significant duration and as of 23 April is still undergoing inspection.
Passenger Experience & Cabin Conditions
As a freighter operation, there were no passengers aboard. The crew and any additional load personnel evacuated the aircraft normally and did not require medical attention.
There was no smoke, fire, or decompression. The cargo loadout—presumably palletised freight—remained secure.
Emergency Response & Aftermath
Airport emergency services responded immediately to the immobilised aircraft. Firefighting units inspected the gear assemblies for thermal stress, overheating, and potential hydraulic fluid leaks. Ground personnel began cooling efforts and asset recovery planning.
Runway 17R remained operational, though the adjacent taxiway where the aircraft stopped was restricted pending the recovery and replacement of all tyres.
Sky Lease’s ground engineering and logistics teams arrived to coordinate tyre replacements, brake checks, and any required engine diagnostics.
Investigation Status
At present, the Directorate General of Civil Aviation (DGAC) Chile has initiated a formal investigation. The U.S. Federal Aviation Administration (FAA) and National Transportation Safety Board (NTSB) are expected to be informed due to the aircraft’s U.S. registration.
Investigators are reviewing:
Engine start and takeoff data Cockpit voice and flight data recorders (CVR/FDR) Brake temperature trends during RTO Pre-flight defect logs for engine or brake system alerts Surveillance footage of the takeoff run for external engine behaviour
Root Cause & Contributing Factors
The primary root cause is expected to be an engine malfunction during high-speed acceleration, severe enough to justify an RTO above 160 knots.
Contributing factors include:
Takeoff near or at MTOW for a transcontinental cargo sector Heat transfer during full-braking RTO on long runway Brake and tyre system limitations under maximum kinetic energy conversion Potential delay in deceleration initiation post-anomaly recognition
Safety Recommendations & Industry Impact
Pending the investigation’s outcome, future advisories may include:
Review of RTO decision thresholds and training for high-weight freighter operations Inspection protocols for high-speed brake system stress events Component-specific service bulletins from GE if a hardware failure is confirmed Operator reviews of tyre lifespan, brake energy monitoring, and turnaround cooling time
Freighter aircraft carry increased takeoff mass and higher centre-of-gravity load distribution, which amplifies brake and tyre demands in the event of RTO.
Conclusion
Sky Lease Cargo flight GG4550’s high-speed rejected takeoff due to an engine problem resulted in a full brake application and the controlled deflation of all 16 main landing gear tyres. The aircraft was safely brought to a stop and no injuries were reported. While the exact engine fault remains under investigation, the incident illustrates the high-risk, high-energy environment of freighter operations and the importance of brake/tyre design in runway overrun prevention.
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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