Helios, a proof-of-concept solar-electric flying wing, was designed to operate at extremely high altitudes for long duration. It crashed during a checkout flight from the U.S. Navy Pacific Missile Range Facility (PMRF) on Kauai, Hawaii.

No property damage, other than the prototype, or injuries occurred as a result of the mishap. The remotely piloted aircraft came down in the ocean, within the confines of the PMRF test range, west of the facility. The cause of the mishap is under investigation.

The solar-electric, propeller-driven aircraft had been flying under the guidance of ground-based mission controllers for AeroVironment, Inc., of Monrovia, Calif., the plane's builder and operator. The lightweight flying wing had taken off from PMRF at about 5:00 a.m. EDT on a functional checkout flight. Helios had been aloft for about 29 minutes. The mishap occurred during a shakedown mission in preparation for a long-endurance flight planned for next month.

The Helios Prototype is one of several remotely piloted aircraft whose technological development has been sponsored and funded by NASA under the Environmental Research Aircraft and Sensor Technology program. NASA's Dryden Flight Research Center, Edwards, Calif. manages the program.

Current to power Helios' electric motors and other systems during the day was generated by high-efficiency solar cells spread across the upper surface of its 247-foot long wing. At night Helios was powered by an experimental fuel cell- based electrical system.

The Helios Prototype was designed to fly at altitudes of up to 100,000 feet on single-day atmospheric science and imaging missions, as well as perform multi-day telecommunications relay missions at altitudes from 50,000 to 65,000 feet. The Helios Prototype set a world altitude record for winged aircraft, 96,863 feet, during a flight in August 2001.

NASA, supported by AeroVironment and the U.S. Navy, to determine the exact cause of the Helios Prototype mishap, will form an accident investigation team.

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