Frankfurt, July 11 - Lufthansa flight LH510, operating the airline’s longest regularly scheduled route from Frankfurt, Germany (FRA) to Buenos Aires, Argentina (EZE), on July 7, 2025, encountered a series of extraordinary challenges that culminated in a rare mayday declaration. The flight, covering a distance of 7,133 miles and typically lasting just over 13 hours, was operated by a Boeing 747-8, registered as D-ABYM. Departing Frankfurt at 10:28 PM, the flight was expected to land in Buenos Aires at approximately 6:25 AM the following morning. However, deteriorating weather conditions at the destination set off a chain of events that extended the journey to nearly 20 hours and resulted in the flight’s cancellation.
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As the Boeing 747-8 approached Buenos Aires, poor visibility due to adverse weather forced the crew to enter a holding pattern at 7,000 feet. Unable to land safely, the pilots made the decision to divert to Asuncion, Paraguay (ASU), an alternate airport. After landing in Asuncion, the crew awaited improved weather conditions in Buenos Aires, but the situation remained unfavorable. With operational constraints mounting, the aircraft diverted a second time to São Paulo, Brazil (GRU), a Lufthansa-served hub located 1,069 miles from Buenos Aires. The jet touched down in São Paulo at 1:04 PM, roughly 20 hours after it departed from Frankfurt. During the final approach to São Paulo, the crew declared a mayday, an emergency call reserved for situations posing immediate danger to the aircraft. Air traffic control recordings later revealed that the declaration was prompted by a combination of crew fatigue and low fuel reserves.
The extended flight duration, compounded by holding patterns and two diversions, had pushed the crew beyond their regulated duty limits and strained the aircraft’s fuel supply. The mayday call triggered standard protocol, with emergency services, including fire trucks, meeting the aircraft upon landing in São Paulo. The declaration was notable, as citing crew fatigue as a primary reason for a mayday is highly unusual. While low fuel is a clear justification for such an emergency, fatigue is typically managed through scheduling regulations rather than emergency declarations.
With the crew legally timed out and unable to continue, Lufthansa canceled flight LH510. Strayed after nearly a full day aboard, passengers were rebooked on alternate flights from São Paulo to Buenos Aires or their final destinations. The Boeing 747-8 remained grounded in São Paulo, with Lufthansa yet to confirm whether it would be ferried back to Frankfurt or continue to Argentina for future operations. This incident underscores the complexities of ultra-long-haul flights, where unpredictable weather, limited alternate airports, and strict crew duty regulations can create significant operational challenges. The safe landing in São Paulo, despite the extraordinary circumstances, highlights the crew’s critical decision-making under pressure, ensuring the safety of all aboard.