NTSB Identification: FTW99FA001A
Accident occurred Monday, October 05, 1998 in VERMILION 331
Probable Cause Approval Date: 07/17/2001
Aircraft: Bell 407, registration: N403PH
Injuries: 1 Fatal,1 Minor.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The Bell 407 collided with an Aerospatiale AS-355-F1 while both helicopters were in cruise flight at 1,000 AGL over open ocean in the Gulf of Mexico. Both aircraft were being flown single pilot and were positioning flights between offshore platforms. The pilot of the Bell initiated an autorotation to the water and was rescued. The pilot of the Aerospatiale was fatally injured during the collision/water impact sequence and his helicopter impacted the water and sank into the ocean. Physical evidence on the recovered Bell wreckage indicated that the main rotor blades of the Aerospaciale struck the nose section of the Bell, removing the windshield, chin bubble and anti-torque pedals. The Bell's direct flight course was about 265 degrees. The Aerospatiale's direct course was about 155 degrees. The Bell pilot did not see the Aerospatiale until just before impact. The Helicopter Safety Advisory Conference (HSAC) had published a Recommended Practice (RP) in 1993 for standardized vertical separation of helicopters when flying in the offshore environment. Excerpts are: 'Helicopters operating enroute to and from offshore locations, below 3,000 feet, weather permitting, should use [the following] enroute altitudes; Magnetic Heading of 0 to 179 degrees - 750 feet or 1,750 feet, or 2,750 feet, Magnetic Heading of 180 to 359 degrees - 1,250 feet or 2,250 feet.' These recommended altitudes, if used, provide a minimum of 500 feet vertical clearance. Both operators, who are participating members in HSAC, did not have the HSAC-RP No. 93.1 included in their respective operations manuals. The RP's are recommended and not mandatory.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

the failure of both pilots to see and avoid each other's aircraft during cruise flight. Factors were the failure of both pilots to use a known safety advisory recommendation and the failure of both operators to implement the recommendation as a company operating procedure.

Full narrative available

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