The DHC-6 Twin Otter suffered a wing tip strike during a crosswind landing at Blois/Le Breuil Airfield, France. The aircraft was attached to the French Transport Squadron 3/61 Poitou, stationed at Orl‚ans Bricy Air Base (BA123). It had been equipped with a large diameter and low pressure wheel kit (IFG) for the last ten days. On the day of the accident the flight crew was to practice short field landings at Blois/Le Breuil Airfield. On the fifth landing, the pilot in command was at the controls in the right seat. He wanted to land the aircraft near the threshold of the asphalt runway 12/30, with a right crosswind of 13 kt and gusts to 18 kt. Upon contact with the ground, the crew heard a squeal of tires. The aircraft veered to the right. The right wing lifted and the left wing touched the ground in a right yaw. The aircraft exited the runway to the right and came to rest on a grass runway, 30 meters from the edge of the paved runway. Causes of the event: The causes of the event fall within the environmental, organizational, and human factors domains. The crosswind on landing was at the limits of the aircraft’s operating range. The piloting of the Twin Otter, in crosswind conditions at the limits of use, is delicate and requires precision and reactivity. The constrained planning of the flights led the crew to carry out a light preparation of this flight. The recent modification of the aircraft with the half-balloon wheel kit was not sufficiently consolidated for a complete appropriation by the crews. In the absence of a formal authorization of use, the pilots discover by themselves the particularities of this new configuration. The crews have not taken the measure of the new phenomena brought by the change concerning the centering, the attitude of the aircraft and the increased effectiveness of the braking system. The crew, by a bias of habit, kept their usual reference points and acted on the controls by going to the maximum travel of these without being able to counter the drift and the slide which was installed. The repetition of the exercises since the first flight of the day could have led to a decrease in the captain’s attention, favouring the occurrence of a piloting error linked to cognitive biases of habit. The ignorance of the particular phenomenon of the scrambling, known of this type of aircraft led to an underestimation of the risk associated with a very front centering. The characteristics of the mission could have favored a wrong perception of the risk. The important aeronautical experience of the crew contributed to a feeling of control. A culture of performance strongly permeates the crews of the squadron. This generates a higher level of risk acceptability. The hypovigilance of the captain is a contributing factor to the occurrence of a habit bias in this event. Finally, the pilot in the left seat adopted a passive posture due to the captain’s experience, delaying the resumption of control.