What happened
On the night of July 22, 2001, an Euralair Horizons Boeing 737-400, registration F-GRNZ, was performing an ILS approach to runway 07 at Monastir, Tunisia. The flight originated from Paris Charles de Gaulle and was carrying 172 passengers and 6 crew members.
During the flare phase, the pilot experienced a slight sink rate but did not reduce thrust. This resulted in a first touchdown followed by a bounce. During the subsequent low-altitude flight, the pilot reduced thrust, which caused the spoilers to retract. To mitigate the descent, the pilot applied additional back pressure on the elevator, increasing the aircraft's pitch. This high pitch angle caused the lower fuselage to strike the runway during the second touchdown.
Upon arrival at the parking stand, the commander noticed minor damage to the tail skid. Due to poor lighting conditions and a confirmation bias, the crew did not identify the more extensive structural damage to the fuselage skin and frames. The aircraft subsequently performed its return flight to Paris, where the full extent of the damage—including deformed ribs and torn skin—was discovered by maintenance teams.
The investigation
The investigation focused on the flight parameters recorded by the FDR and the physical damage found during inspections in Paris. Investigators examined the sequence of the landing, specifically the interaction between thrust reduction, spoiler retraction, and the pilot's pitch input. The inquiry also looked into why the structural damage was not detected by the crew in Monastir, noting that the visual inspection was limited to the tail skid and hindered by nighttime visibility and the lack of specific operational procedures for inspecting fuselage integrity after a hard landing.
Findings
- The primary cause of the landing accident was insufficient thrust reduction during the first touchdown and the failure to execute a go-around after the bounce.
- The retraction of the spoilers following thrust reduction, combined with the pilot's increased pitch input, led to the fuselage contacting the runway.
- The failure to detect the structural damage was attributed to the crew's focus solely on the tail skid and the challenging lighting conditions at the airport.
- The lack of specific documentation regarding the inspection of the fuselage after a hard landing contributed to the risk of the subsequent flight.