What happened
On June 6, 2018, a Cessna 525A CitationJet CJ2+, registered D-IULI, was performing a non-commercial flight from Figari to La Môle. During the approach, the pilot encountered heavy rain and low visibility, necessitating an aborted first approach due to cloud cover.
Upon the second approach, the aircraft touched down approximately 200 meters past the runway threshold. The pilot reported that the braking was ineffective and the wheels appeared to be sliding on the wet surface. The aircraft failed to stop within the available runway length, overrunning the paved surface and exiting the airfield at 41 kt. The aircraft descended into a riverbed, where the nose violently struck the opposite bank. The pilot and one passenger sustained injuries, and the aircraft was destroyed.
The investigation
The BEA examined the aircraft' and the site, noting that the wreckage was partially submerged in a river. The investigation focused on the landing performance calculations used by the crew. It was discovered that the pilot had used a flight file provided by the operator, ProAir, which calculated wet runway landing distances by simply adding a 15% margin to the dry runway distance.
Investigators also reviewed the aircraft's weight and balance, finding that the pilot had omitted the weight of hold luggage, meaning the actual landing weight likely exceeded the maximum landing weight. Furthermore, the investigation highlighted difficulties in accessing full flight data from the aircraft's maintenance recorder due to limitations in the manufacturer's decoding software.
Findings
- The aircraft's landing distance on a wet runway was incompatible with the available runway length at La Môle.
- The pilot relied on an erroneous landing performance calculation derived from an EFB application that used a simplified 15% increase method rather than the specific values required by the Aircraft Flight Manual (AFM).
- The approach speed was higher than the reference speed, and the approach slope was steeper than nominal, further increasing the required stopping distance.
- The operator's operations manual lacked specific safety margins or calculation methods for non-commercial flights.
- The EFB application's interface was found to be misleading, potentially leading pilots to believe the 15% margin was appropriate for all flight types.