Terrain collision avoidance systems for turbine powered helicopters

Citation

(2006), "Terrain collision avoidance systems for turbine powered helicopters", Aircraft Engineering and Aerospace Technology, Vol. 78 No. 4. https://doi.org/10.1108/aeat.2006.12778dab.020

Terrain collision avoidance systems for turbine powered helicopters

Terrain collision avoidance systems for turbine powered helicopters

Keywords: Helicopters, Aircraft safety

The National Transportation Safety Board today called on the Federal Aviation Administration to require all US-registered turbine-powered helicopters certificated to carry at least six passengers to be equipped with a terrain awareness and warning system. The recommendation is one of five contained in the final report of a fatal helicopter accident in the Gulf of Mexico.

On March 23, 2004, an Era Aviation Sikorsky S-76A++ helicopter, N579EH, crashed into the Gulf of Mexico at about 7:18 p.m., 70 nautical miles south-southeast of Galveston, Texas. Although visual meteorological conditions existed, it was a dark night with very few external visual cues. The aircraft was transporting eight oil service personnel to the Transocean drilling ship Discoverer Spirit; they and the two pilots perished in the crash.

The board determined that the probable cause of the accident was the flight crew's failure to identify and arrest the helicopter's descent for undetermined reasons, which resulted in controlled flight into the water.

“A terrain warning system would have given the pilots enough time to arrest their descent and save the lives of all aboard,” NTSB Acting Chairman Mark V. Rosenker said. “It is well past time for the benefits from these standard safety devices to be made available to passengers on helicopter transports as they are on fixed wing planes. More than two million passengers are carried on Gulf of Mexico oil industry operations alone.”

The aircraft was not equipped with a flight data recorder, and the cockpit voice recorder was improperly installed, rendering the recording almost unusable. The board, therefore, could not determine the sequence of events that led to the helicopter's inadvertent descent. However, since cockpit instrumentation was available to the pilots, the board concluded that the flight crew was not adequately monitoring the helicopter's altitude and missed numerous cues to indicate that the aircraft was descending toward the water.

The board noted that when the FAA required TAWS (terrain awareness and warning system) for aeroplanes having six or more passengers in 2000, the technology had not been developed for the unique characteristics of helicopter flight. However, TAWS technology is now available for helicopter flight and should be required, the board said.

In 2003, the FAA exempted S-76A and several other helicopter models from its requirement that they be equipped with flight data recorders. In an earlier letter to Era, the FAA had stated that exempting the helicopters from the FDR requirement “would be in the public interest and would not adversely affect safety.”

The board disagreed with that assessment, stating, “because the information that investigators learn from FDR data can help prevent accidents and incidents from recurring, the lack of FDRs aboard helicopters undoubtedly affects safety.” The NTSB noted that it had participated in the investigation of another S-76 helicopter crash in Estonia. This was the first accident known to involve a large helicopter for which FDR data was available. Those data were extremely valuable to investigators, the board said. The lack of FDR data significantly hampered the Era investigation, the Board said, and it urged the FAA to require FDRs on commercial helicopters such as the one involved in the Gulf of Mexico crash.

The board also recommended that cockpit voice recorders on aircraft be functionally checked flight of each day and that a periodic maintenance check be accomplished as part of the approved maintenance check of the aircraft.

Other recommendations to the FAA dealt with expedited implementation of an initiative to improve flight following where traditional radar coverage does not exist, such as in portions of Alaska and the Gulf of Mexico, and with proper training for certain flight control systems.

A summary of the board's findings is available on the board's web site: www.ntsb.gov, under “Publications.” The entire accident report will appear on the web site in several weeks.