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ASN Wikibase Occurrence # 145713
Last updated: 12 December 2017
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Date:18-MAY-2012
Time:12:12
Type:Silhouette image of generic HUNT model; specific model in this crash may look slightly different
Hawker Hunter F.Mk 58
Owner/operator:Atac
Registration: N329AX
C/n / msn: 41H-003067
Fatalities:Fatalities: 1 / Occupants: 1
Airplane damage: Written off (damaged beyond repair)
Category:Accident
Location:1.5mi from Point Mugu NAS, CA -   United States of America
Phase: Landing
Nature:PUBF
Departure airport:Point Mugu, CA (KNTD)
Destination airport:Point Mugu, CA (KNTD)
Investigating agency: NTSB
Narrative:
The pilot was appropriately rated to act as pilot in command of the airplane for the intended mission. There was no weather, air traffic control, powerplants, or airplane airworthiness factors in the accident. The accident pilot initiated an ejection at some point after the airplane departed controlled flight, however, the airplane's attitude and altitude were outside the envelope for a successful ejection.

While troubleshooting the lateral imbalance condition that was encountered immediately after takeoff, the accident pilot was aware of the maintenance involving the left fuel transfer valve motor two days prior to the accident flight and quickly concluded that he had a fuel imbalance. He also indicated in communications with the flight lead that he was not certain if he had verified the fuel load during the pre-flight inspection. The airplane was controllable at this point; however, he elected to continue the flight even after the flight lead recommended that he return to base. As the flight progressed, the accident pilot also indicated that he believed he had a transfer problem from the left side tanks, resulting in fuel burning from the right side and no fuel burning from the left wing tanks, thereby exacerbating the lateral imbalance as the flight continued. Although the pilot likely did not verbalize every switch change that he performed in the cockpit, some of the information that was relayed was inconsistent with the design of the fuel system, possibly indicating that the pilot's understanding of the fuel system was limited. The pilots initial training on the Hunter at ATAC was reduced in time, potentially causing some lack of full understanding of systems. Therefore, the accident pilot elected to continue to the mission area, about 140 miles from the departure airport, with a known fuel imbalance condition, contrary to the airplane flight manual and the flight lead's recommendation.

After the pilot did decide to return to base, he made no more statements about the stick position or controllability of the airplane nor did the pilot declare an emergency which would have been appropriate given his urgent situation. Although there was insufficient data to conclsively determine the reason for the departure from controlled flight, it is likely that the pilot continued to counter the "heavy" wing with opposite aileron until full authority was attained and he was unable to further arrest the roll. At this point in the flight, the fuel unbalance was significantly greater than the maximum unbalance limitation in the Hunter manual and so controllability, especially at slower speeds, would have been questionable. Additionally, it is possible that the pilot may have elected to extend the flaps early during the approach, which would have aggravated the roll tendency as also stated in the Hunter manual. This scenario could not be confirmed because there was no radio communications from the pilot during this time, nor could the flap position be conclusively determined in the wreckage.

ATAC did not have a crew resource management or aeronautical decision making training program in effect. If such a program had been in effect, it may have led the accident pilot to follow the flight lead's recommendation and return or divert rather than continue the flight and troubleshoot.

Two days prior to the accident, ATAC maintenance replaced left fuel transfer valve assembly. The mechanic that conducted the work had never performed this task and expressed difficulty and confusion with completing it and had to request assistance from other personnel. No type-specific maintenance training exists for the Hunter and all maintenance training is conducted on-the-job. Although ATAC did have the appropriate manuals on hand to guide the replacement, the maintenance personnel were not aware that they had the British manuals, and only referenced the Swiss French-language manuals, which they could not translate. No task cards, detailed step-by-step instructions for maintenance tasks, existed for the Hunter due to the le
Probable Cause: the pilot's decision to continue the flight with a known fuel imbalance condition that resulted in a loss of lateral control when the imbalance exceeded the known capabilities of the airplane. The fuel imbalance was due to incomplete refueling and an ineffective preflight inspection by the pilot. The imbalance was further complicated by an incorrectly assembled fuel transfer valve and motor combination.

Contributing to the severity of the accident was the pilot's delayed decision to eject prior to exceeding the ejection seat envelope. Also contributing to the accident was (1) the Navy's oversight environment, which did not require airman, aircraft, and risk management controls or standards expected of a commercial civil aviation operation, and (2) ATAC's organizational environment, which did not include CRM training to promote good aeronautical decision-making and ORM guidance to mitigate hazards. Also contributing to the accident were the design features of the airplane, which were typical of its generation, including the lack of accurate fuel quantity indications, the design of the fuel transfer valve; and the maintenance program's lack of clearly documented procedures and type-specific training for the Hunter.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20120518X65127&key=1
FAA register: 6. http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=329AX&x=-797&y=-453


Revision history:

Date/timeContributorUpdates
18-May-2012 15:52 gerard57 Added
19-May-2012 01:51 gerard57 Updated [Operator, Source, Narrative]
19-May-2012 03:14 Masen63 Updated [Aircraft type]
19-May-2012 09:02 Dr. John Smith Updated [Time, Registration, Cn, Location, Departure airport, Destination airport, Source, Narrative]
19-May-2012 11:52 Dr. John Smith Updated [Registration, Cn, Embed code]
20-May-2012 03:45 Masen63 Updated [Aircraft type, Embed code, Narrative]
20-May-2012 06:16 FLYINGBROTHER1 Updated [Time, Location, Departure airport, Destination airport, Embed code]
19-Jun-2012 22:43 Geno Updated [Registration, Cn, Source, Embed code, Narrative]
15-Jun-2013 03:37 Dr. John Smith Updated [Time, Registration, Cn, Location, Source, Embed code, Narrative]
29-Aug-2016 12:54 Aerossurance Updated [Time, Aircraft type, Operator, Location, Source, Narrative]
29-Aug-2016 12:56 Aerossurance Updated [Narrative]
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
23-Aug-2017 10:35 Aerossurance Updated [Time, Operator, Location, Departure airport, Destination airport]
27-Nov-2017 20:39 ASN Update Bot Updated [Time, Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]

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