Date: 29th November 2024
Location: Enroute over the Mediterranean Sea, diverted to Athens, Greece
Aircraft: Boeing 757-300, registration D-ABON
Operator: Condor
Flight Number: DE-30
Route: Frankfurt/Main (Germany) to Hurghada (Egypt)
Occupants: Unknown
Injuries: None reported
Summary of Events
On 29th November 2024, Condor flight DE-30 from Frankfurt to Hurghada, operating a Boeing 757-300, encountered a dual navigation computer failure while cruising at FL350 approximately 280 nautical miles southeast of Athens. The crew opted to turn around and divert to Athens International Airport (LGAV). The aircraft landed safely on runway 21R approximately 50 minutes later.
After a complete power shutdown and reset of the navigation computers, the aircraft refueled and continued to Hurghada, arriving with a delay of approximately 4 hours. The return flight DE-31 was postponed until the next day due to the incident, ultimately reaching Frankfurt 19 hours behind schedule.
Aircraft Information
The Boeing 757-300 is a twin-engine, narrow-body aircraft widely used for medium- to long-haul operations. The aircraft is equipped with multiple navigation systems, including dual inertial reference systems (IRS) and flight management computers (FMC), providing redundancy in the event of a single system failure.
Sequence of Events
1. Cruise Phase:
• The aircraft was enroute at FL350 over the Mediterranean Sea when the crew experienced failures in two navigation computers, severely impacting situational awareness and flight management.
2. Decision to Divert:
• Given the criticality of navigation systems, the crew decided to divert to Athens for maintenance support.
3. Landing in Athens:
• The aircraft landed safely on runway 21R at Athens International Airport approximately 50 minutes after the decision to divert.
4. Maintenance Action:
• After landing, the crew shut down the aircraft completely, allowing for a full reset of the navigation computers.
• The maintenance action appeared successful, and the aircraft was refueled.
5. Continuation of Flight:
• The flight continued to Hurghada, arriving with a delay of approximately 4 hours.
6. Impact on Return Flight:
• The return flight DE-31 was postponed until the following day, with a delay of about 19 hours before reaching Frankfurt.
Initial Findings
Navigation Computer Failures
• The dual navigation computer failure may have been caused by:
• Software Glitch: Temporary errors in the flight management system or inertial reference system.
• Power Anomalies: Voltage fluctuations or interruptions causing system instability.
• Environmental Factors: Possible electromagnetic interference while over the Mediterranean.
System Reset
• The full power shutdown and reset procedure successfully restored the navigation systems, suggesting the issue was transient rather than hardware-related.
Safety Risks
1. Navigation Dependency:
• Loss of two navigation computers significantly reduces redundancy and may compromise the ability to safely navigate and manage the flight.
2. In-Flight Diversion:
• Diverting mid-flight increases operational risks, including unfamiliar airspace and increased crew workload.
3. Potential Delays:
• The incident caused significant disruptions to the flight schedule, including a 19-hour delay for the return flight.
Recommendations
1. Enhanced Diagnostics:
• Conduct a detailed investigation into the cause of the navigation computer failure, including a review of software logs and hardware health.
2. Crew Training:
• Reinforce training for pilots on managing dual navigation system failures and ensuring safe diversions.
3. System Reliability:
• Review the health of navigation systems fleet-wide and ensure software and firmware updates are current.
4. Redundancy Protocols:
• Evaluate procedures for handling dual failures, including backup navigation options and communication with air traffic control.
Safety Lessons
This event underscores the importance of robust navigation system reliability and the value of having clear diversion protocols. The successful diversion and restoration of systems highlight the effectiveness of the crew’s decision-making and the importance of maintenance support at alternate airports.
Disclaimer
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Our investigation reports are based on all the evidence and facts available at the time of writing and posting. We apologise if any details are missed or are not fully accurate.
