ASN Wikibase Occurrence # 36053
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| Date: | Monday 5 October 1998 |
| Time: | 09:06 |
| Type: |  Bell 407 |
| Owner/operator: | Petroleum Helicopters (PHI) |
| Registration: | N403PH |
| MSN: | 53177 |
| Year of manufacture: | 1997 |
| Total airframe hrs: | 1168 hours |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Other fatalities: | 1 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | 220 km S of White Lake, LA -
 United States of America
|
| Phase: | En route |
| Nature: | Offshore |
| Departure airport: | Vermilion 331A , GM |
| E. Cameron 321A, Gulf of Mexico | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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 underside 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 nor in their training syllabus. The RP's are recommended and not mandatory. The accounts of the surviving pilots statements and subsequent findings of the FAA/NTSB post accident investigation of the recovered Bell 407 conclude that the pilot of the Bell 407 was over taken from the 4 o'clock to 5 o'clock position. While both aircraft have similar cruise airspeed, the Bell 407 was at the time being operated at a indicated airspeed of 105 knots due to an airworthiness directive initiated by preceding accidents attributed to the tail rotor striking the tail boom in forward flight due to excessive tail rotor flapping or inadvertent/excessive tail rotor input. The pilot of the Bell 407 first "heard" the Twinstar approach from, as stated "the four thirty to five o'clock position" and initiated a left roll away from the approaching aircraft as evidenced by the damage to underside of the Bell 407s skid which removed the pilots tail rotor anti torque pedals, chin bubble, and cut through the skid cross tube and left front skid and emergency flotation device. Strike marks to the Bell 407s underside left transfer marks in the color of the Twinstars main rotor blades. Subsequent interviews found that the pilots windshield and nose damage occurred post accident during the recovery process. Given these details and subsequent to the FAA/NTSBs investigation and statements from the surviving pilot, no action was considered or taken against the surviving pilot.
CAUSE: 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.
Sources:
https://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20001211X11250
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 24-Oct-2008 10:30 | ASN archive | Added |
| 30-Mar-2012 12:31 | harro | Updated |
| 03-Mar-2013 11:36 | TB | Updated [Operator, Source] |
| 03-Mar-2013 11:38 | TB | Updated [Location, Country] |
| 21-Dec-2016 19:22 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 03-Feb-2017 06:43 | Anon. | Updated [Narrative] |
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