Tempête fatale à Düsseldorf – Épisode complet |  AIR CRASH (S25)

Flight 108: The Tragic Crash of Nuremberg Air Service

Overview of the Incident

• Flight 108 from Nuremberg Air Service disintegrates mid-air while attempting to land at Düsseldorf Airport, resulting in the death of all occupants.

• Due to the extensive crash site, a grid system is established to locate debris. Investigators uncover a rare malfunction that should not have caused the aircraft's fall.

Flight Preparation and Conditions

• The flight crew consists of Captain Ralph Borsdorf (36 years old) and First Officer Sybille Aylman (28 years old), both with 2,500 flight hours.

• Weather forecasts indicate calm conditions with a slight risk of turbulence near Düsseldorf; however, pilots consider this manageable.

• The aircraft requires de-icing before departure due to overnight snow accumulation. There are 19 business passengers on board for a short flight.

Aircraft Details and Initial Flight Phase

• The Metroliner 3 is described as an ideal aircraft for short-distance flights—fast, economical, and comfortable for its size.

• After reaching cruising altitude of 14,000 feet within ten minutes, the crew prepares for descent amidst significant workload due to short domestic flights.

Approach to Düsseldorf

• As they approach Düsseldorf, radar indicates storm activity ahead. Pilots expect weather improvement but remain cautious about thunderstorms.

• Communication with air traffic control confirms their descent instructions as they prepare for landing at Düsseldorf Airport.

Encountering Adverse Weather

• Just before landing, the first officer checks weather radar again and notes an approaching storm directly in their path.

• The captain decides to navigate around the storm rather than fly through it—a critical decision given potential hazards associated with thunderstorms.

Final Moments Before Crash

• Shortly after switching frequencies to tower control for landing clearance, Flight 108 disappears from radar screens.

• Witnesses report seeing the Metroliner descend rapidly from cloud cover at alarming speeds just before crashing into a field near Düsseldorf.

Aftermath and Investigation Efforts

• Eyewitness accounts describe a last-minute attempt by pilots to regain control as the plane descends at 4,000 feet per minute; however, it ultimately spirals out of control.

• Emergency responders arrive quickly but find no survivors among the wreckage scattered over a wide area.

• Investigators begin mapping debris locations in hopes of reconstructing events leading up to this tragic accident.

Investigation of Flight 108 Crash

Initial Steps in Debris Analysis

• The first step involves accurately noting the position of each piece of debris from the aircraft. Due to the size of the crash site, a grid system was established to identify all debris locations.

Condition of Black Boxes

• The aircraft was destroyed upon impact, and its black boxes were severely damaged. Unlike modern models that can record numerous parameters, these were older analog versions capturing limited data such as altitude and wind speed.

Analyzing Debris for Clues

• Once recovered, investigators analyze debris to determine which parts broke off during the crash. Some components remained intact, suggesting they fell separately from the main body of the aircraft, indicating in-flight destruction before hitting the ground.

Investigating Possible Causes

• Investigators consider various hypotheses regarding structural failure:

• Could a design flaw or fatigue have caused wing loss?

• Was there a manufacturing defect?

• Did an issue arise early in the aircraft's life?

They rule out fatigue cracks but explore overload fractures due to excessive speed or severe turbulence.

Flight Path Examination

• To understand how structural limits were exceeded, investigators review the flight plan which appeared normal initially. However, unusual maneuvers were noted prior to crashing, likely increasing load factors on approach. This led them to interview air traffic controllers about conditions at that time.

Weather Conditions and Pilot Reports

• During interviews with air traffic control:

• Light icing and turbulence were reported; however, other flights landed without issues.

• A nearby flight experienced lightning but reported no damage.

Investigators note that while thunderstorms are common concerns for pilots, wind gusts pose greater risks during approaches.

Electrical Failure Insights

• As investigations continue into why tight maneuvers occurred:

• Both black boxes ceased recording two minutes before impact—coinciding with these maneuvers.

• This suggests a total electrical failure affecting both systems simultaneously is possible since both power sources failed at once despite low probabilities according to manufacturer data.

Consequences of Electrical Failure

• Pilots lost most instruments due to general electrical failure but retained some critical ones like variometers and artificial horizons for navigation purposes as they continued their investigation into this anomaly.

Investigation of Electrical Failure in Metro-Liner

Introduction to the Artificial Horizon

• The metro-liners are equipped with a third artificial horizon, independent of the other two. This horizon operates using air from the engines and does not rely on electrical systems.

• Pilots could use this backup artificial horizon to maintain aircraft orientation, raising questions about its non-use during emergencies.

Investigating Instrument Lighting Issues

• A critical question arises: why didn't pilots utilize the backup horizon? One possibility is that instrument lighting may have failed, rendering visibility impossible.

• Investigators examine dashboard bulbs from flight 108 to confirm if they were active at the time of the crash; broken filaments would indicate no power was present during impact.

Establishing General Electrical Failure

• All examined filaments were found broken, confirming a total electrical failure occurred before impact. Investigators consider lightning strikes as a potential cause for this failure.

• Lightning can create circuit issues within an aircraft if it strikes externally, leading investigators to search for signs of lightning impact on the fuselage amidst debris.

Tracing Lightning Impact and Damage

• Lightning leaves circular marks on aircraft surfaces; investigators look for burn marks or melted metal as indicators of where lightning struck. They must also determine which systems were affected by this strike.

• Reconstructing parts of the aircraft is necessary due to limited data available at the time of investigation; such reconstructions were common practice then.

Analyzing Electrical Circuit Damage

• Evidence suggests that lightning struck near electrical bundles behind where it impacted, prompting further investigation into whether it caused a general power failure through these circuits.

• Investigators focus on finding insulation damage or melted wires indicating heat transfer from lightning energy into wiring systems nearby. However, initial inspections yield no significant findings yet.

Exploring Avionic Component Failures

• As investigations continue without clear evidence of damage from lightning in electrical circuits at impact points, attention shifts towards avionics components for potential failures caused by high voltage surges from lightning strikes.

• Diodes onboard are tested; they should only allow current in one direction but show low resistance in both directions—indicating they are short-circuited and dysfunctional due to excessive voltage exposure possibly linked to lightning events.

Conclusion: Understanding Diode Failures

• Further analysis reveals all diodes tested are defective with cracks suggesting they failed under extreme conditions; tests indicate that normal diodes require around 1000 volts to fail while lightning produces hundreds of millions of volts—confirming their destruction likely resulted from a lightning strike event impacting circuitry integrity significantly.

Is It Possible for an Airplane to Generate Such High Voltage?

Lightning Strike Impact on Aircraft Systems

• The high voltage experienced could not have been generated by the aircraft itself; it was caused solely by a lightning strike that hit the fuselage and short-circuited the electrical system.

• Following the lightning strike, the entire electrical network of the airplane failed, which is typically unlikely but did occur in this case. This raises questions about pilot decisions during storm approaches.

Pilot Decision-Making During Storm Approaches

• Standard protocol dictates that pilots should avoid thunderstorms regardless of their size; they should divert or wait rather than enter them. Investigators are examining why Flight 108's pilots chose to fly into a storm.

• Multiple options were available to the pilots: preparing for potential turbulence or diverting to an alternate airport instead of proceeding through adverse weather conditions.

Crew Communication and Coordination Issues

• As they approached Mishmain, crew members noted poor weather conditions but initially underestimated their severity based on radar and TIS reports from Düsseldorf Airport, which indicated no storms present.

• After receiving information suggesting improvement in weather conditions, the captain decided to continue with the approach despite potential risks associated with thunderstorms. Professional pilots are trained to prepare for worst-case scenarios even when risks seem low.

Reaction to Preceding Aircraft Incident

• Eleven minutes later, tension escalated as another aircraft ahead had suffered a lightning strike during its final approach; if in command, one pilot would have opted for a go-around due to safety concerns regarding entering a thunderstorm directly behind another affected plane.

• There was noticeable tension between cockpit crew members as they discussed options without fully coordinating their actions or intentions regarding weather avoidance strategies leading up to landing.

Investigation into Pilot Experience and Dynamics

• Investigators analyzed communication records revealing misalignment between the captain and first officer regarding flight path adjustments amidst inclement weather; this lack of coordination contributed significantly to decision-making failures during critical moments before landing.

• The captain had significantly fewer hours flying this specific aircraft type compared to his first officer, who possessed more experience—this dynamic may have influenced cockpit interactions negatively during stressful situations like approaching severe weather conditions.

Flight 108: The Impact of Lightning Strike on Control

Descent and Loss of Control

• The commander adjusts the trim downwards, causing the aircraft to pitch down. He continues to add downward trim, leading to a critical situation as lightning strikes.

• Following the lightning strike, an electrical failure occurs, making flight controls significantly heavier and rendering instruments unreadable due to loss of power.

• Pilots must rely on experience in emergencies; however, lack of communication tools like flashlights hampers their ability to assist each other during the crisis.

Communication Breakdown

• With no intercom functioning due to electrical failure, crew communication becomes impossible in the noisy cockpit environment. This disorientation raises questions about their ability to pilot effectively.

• Despite having control over some flight surfaces like ailerons and rudder, without instrument visibility they struggle with orientation as Flight 108 descends uncontrollably.

Critical Moments Leading to Crash

• The backup artificial horizon light is off, leaving pilots with no external visibility or reliable instruments. Investigators conclude that these factors contributed significantly to the crash.

• A dysfunctional crew dynamic emerges; instead of providing constructive feedback, one pilot criticizes another without offering solutions or guidance.

Turbulence and Structural Failure

• As Flight 108 enters severe turbulence post-lightning strike, pilots face extreme conditions for over a minute while struggling blindly against violent forces affecting aircraft stability.

• Pilots lose spatial awareness amid intense maneuvers; reliance on sensory perception proves misleading under such stress.

Investigation Findings and Recommendations

• The aircraft experiences structural failure due to excessive load factors during turbulent maneuvers; critical components like engines detach from their mounts.

• Investigations reveal that experienced pilots should have avoided flying into storms. Effective communication is emphasized as crucial for preventing similar incidents in future flights.

• Regulatory bodies stress improved training protocols focusing on resource management and teamwork among crews has evolved positively for flight safety.