Kaiko has been the only one full ocean depth survey system in the world since 1995. She has accomplished more than 20 dives to 11000 m at Challenger Deep in the Mariana Trench. Unfortunately, in May 2003, the secondary cable of the Kaiko was snapped during 296th dive at a depth of 4675 m, and the vehicle has been missing. The secondary cable was snapped because the aramid fiberss had weakened by bending under extremely high water pressure, and local fatigue of the strength members occurred at the cable termination. Taking into consideration the valuable lessons of the accident, JAMSTEC will build new and advanced Kaiko as early occasion as possible.
In May 29th in 2003, the Kaiko completed the 296th dive at a depth of 4675 m in the Nankai Trough 130 km southeast off Cape Muroto in Shikoku Island. By successfully recovering bore hole data from ODP Hole 808I the operator tried to reel in the secondary cable to mate the launcher and the vehicle. However, they could not be mated, and the optical line and the electricity failed successively, a black out has occurred. Then, the primary cable was reeled in slowly. After the launcher surfaced, they found that the vehicle end of the secondary cable was snapped, and the vehicle did not appear on the surface. Soon after the launcher was on deck, clear radio signal of the beacon from the vehicle was received on the R/V Kairei, and they knew that the vehicle was on the surface. The radio signal stopped after three successive pulses, and it was never heard since then. Extensive search for the vehicle was carried out until June 21st from surface and air, based on the simulation by taking current and wind profiles into consideration.
