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Investigation committee into the cause of Daijiro Kato's fatal crash publish their results

Investigation committee into the cause of Daijiro Kato's fatal crash publish their results

Investigation committee into the cause of Daijiro Kato's fatal crash publish their results

The investigation committee set-up to determine the cause of the crash that claimed the life of Daijiro Kato published the results of their findings at a special press debrief in Tokyo on Friday.

A detailed document outlines results concerning the causes and sequences of events and the procedures taken by the representatives including: interviews with track staff, marshals, medical personnel, on-site examination, analysis from the motorcycle including suspension, engine and throttle data, analysis of the motorcycle and its parts (being held at HRC HQ) and analysis of the rider's gear.

The document outlines precisely the damage accrued by Kato's machine and riding attire in the accident and the course of treatment the Honda rider was submitted. The cause of the accident in the opinion of the report is as follows:

"Our evaluation of front suspension stroke, rear wheel speed, rear suspension stroke, and engine speed data collected on-board Kato's motorcycle indicates that the motorcycle was traveling in first gear with the front brake engaged as it decelerated on the approach to the chicane. We surmise that when the rear wheel slip neared approximately 30%, he performed a switchback to bank to the right while moving forward in preparation to enter the chicane.

"We believe that the rise in the rear wheel slip ratio reduced the cornering force needed to maintain vehicle stability, and this caused the bike to begin exhibiting unstable behavior.

"According to the on-board data, we conclude that the engagement of the front brake abruptly changed the load on the rear wheel, which lifted almost entirely off the ground, causing a lateral skid. From data on the change in suspension and acceleration sensors that followed, we can confirm that the vehicle entered a high side-like condition.

We also referred to images and on-board measurements taken during the high side that caused Gibernau's fall on the second day of Round 12 of the World Grand Prix in Brazil.

"From on-board data, we understand that Kato eased up on the front brake in an effort to handle the instability caused by the aforementioned abrupt deceleration."

The report then states that the motorcycle was sent into a weave, and continues:

"Of particular note is that Kato lost his balance in the progression from rear wheel lateral skid toward high side, and maintained considerable steering force on the left handlebar to support himself. We can confirm from surveillance images taken from the direction of the chicane that Kato lost his balance in conjunction with the above sequence of movement changes.

"We also verified on-board data from other competitor's motorcycles to answer the important question of whether the occurrence of weave mode was due to a characteristic of Kato's particular motorcycle.

On-board data from competitor Ukawa's motorcycle shows a clear weave mode occurring after he passed through ‘130R' and began decelerating on the approach to the chicane, but it did not reach divergence in his case, and has not been considered problematic since. It can be seen from the fact that other competitors experienced weave mode in the same race in which Kato's accident occurred that it is a common oscillation phenomenon. In the case of this accident, however, Kato's vehicle was operating at its performance limits."

The rest of the accident is then described:

"Kato veered out in a straight line at approximately 170 km/h from the center-left side of the racing course causing the left side of his bike to violently collide with the tire barrier at approximately 150 km/h, after which he crashed into the adjacent foam barrier at approximately 140 km/h. Kato remained mounted on his bike as it traveled along the tire barrier, but when his bike struck the adjacent foam barrier he was momentarily caught between the compressed foam barrier and the bike."

"As the foam barrier was unable to completely absorb the motorcycle's substantial kinetic energy at that point, the bike flipped forward into the air. Kato was separated from his bike. He plunged head first into the foam barrier, and was then thrown into the air. Rotating horizontally through the air in the manner of a discus, he landed face up in the center of the course 33 meters forward and to the right of the point where he first struck the tire barrier."

After the crash the course of events is then described thus:

"Kato's emergency first aid treatment began with an initial observation at the accident site, where it was ascertained that he had a pulse and weak respiration. In the ambulance during transport from the accident site to the first-aid station, the doctor and rescue worker immobilized his cervical region, removed his helmet, and performed cardiac massage. At the first aid station Kato was unconscious but breathing spontaneously. After two weeks of hospitalization and medical treatment, he died at the hospital on April 20 at 12:42 A.M. of a brain stem infarction."

The report goes onto state that:

"In examining what caused such a serious accident to occur, we of course know that the direct cause of death was the high-speed collision with the barriers and, in particular, the fact that having been dragged along the tire barrier, Kato received a cervical spine injury when he momentarily plunged into the side of the foam barrier in the area where the tire barrier and foam barrier meet. Viewed from the results, we can see that he flew off the course in the S-curve zone, and it is very possible that, if he had been able to decelerate sufficiently once he left the course, the incident might have ended as a simple course departure. Further, if there had not been a gap between the two barriers, Kato would not have crashed into the side of the foam barrier, which would have changed the extent and type of injury he received.

"There had never before been a fatal accident at the site of this accident, and although course improvements had made it a more technical venue, the accident site was not identified as hazardous when each of the competing teams held their practice meets. The course was also certified by FIM, all final checks were completed for staging the race, and no one, including the riders, perceived that the area was dangerous."

MotoGP, 2003

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