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Occurrence Investigation Procedures

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Occurrence Investigation Process

The ASC is responsible for investigating the aviation occurrences of civil aircraft, public aircraft, and ultra-light  vehicle happening in our country’s territory. When a R.O.C. registered aircraft involved in an aviation occurrence occurring on the high seas, in an area of undetermined sovereignty or the occurrence location undetermined, the ASC also investigates the occurrence. If a R.O.C. registered aircraft involved in an aviation occurrence occurring in other country, the state of the occurrence conducts the investigation. The ASC will send accredited representative to participate in the investigation.

After receiving the notification, the ASC has to justify the nature of the occurrence if it meets the definition of occurrence. If an occurrence is confirmed, the ASC will establish an investigation team to investigate the occurrence which includes factual data collection, factual data analysis, conclusion of investigation and proposal of safety recommendations. For the aviation occurrence investigation process, please refer to following chart.

Within a month after the occurrence occurred, the ASC will send a preliminary report to the relevant agencies and the International Civil Aviation Organization(ICAO), and post it on the website according to the ICAO Annex 13. The preliminary report usually includes only very basic and limited information. In a few months after the occurrence, the ASC will publish the factual report of the occurrence merely based on factual data, excluding "subjective opinions" or "analytical judgment." The ASC usually completes the aviation occurrence investigation within a year.

Occurrence Investigation Process

Aviation Occurrence Notification

The ASC assigns a on-duty officer, who are responsible for responding aviation occurrence notifications 24 hours a day. After a notification is received, the first thing is to make sure if it meets definition of occurrence. Either it is an occurrence or the information obtained not enough to determine "not an occurrence", a Go-team would be formed to rush to the scene to collect factual data and conduct interviews with the persons involved. Usually it can be determined if it is an aviation occurrence or not after relevant information obtained by Go-team. However if it was controversial, then the Director of Occurrence Investigation Division would call all available technical staff to join the occurrence verification meeting to discuss and make the determination according to Article 2 of the Aviation Occurrence Investigation Act and the ICAO Annex 13.

On Scene Investigation

Go Team

After receiving the notification and confirming the aviation occurrence, the ASC shall immediately designate a safety investigator on the roster as Investigator-in-charge (IIC) to conduct the investigation. The IIC and other investigators will form a Go-team of the size based on the severity and nature of the occurrence. The Go-team will rush to the scene for collecting evidence, interviewing relevant people and securing the flight recorders. The go team should give the priority to collect the perishable evidence, such as the tire marks and tracks on the ground left by the aircraft during the occurrence, gather the scattered evidential objects and record their locations, conduct alcohol tests for crew members and interview relevant persons.

Investigation Team

The IIC organizes an investigation team of the size based on the severity and complication of the occurrence. In principle, the investigation team consists of the ASC's investigators and professional advisers from the CAA, the airport unit, the air traffic control unit, the airlines, the aircraft manufacturer, the investigation authorities of state of aircraft design, state of aircraft manufacturer. Base on the demanding of the investigation, the investigation team may consist of different expertise, such as flight operations group, aircraft maintenance group, air traffic control group and human factors group etc. One of the ASC's investigators acts as the Group Chairman of each group, and the professionals from other units are group members.

Investigation Groups

Under the investigation team, different professional investigation groups can be organized based on the requirement of the investigation. The names of the groups and the brief description of investigation operations are as follows:

Flight Operations Group:This group gathers all factual data of flight operation, including preflight preparation, flight environment, and history of flight, aircraft performance and crew capability,etc.
Aircraft Structure Group:This group investigates the structures of the aircraft to establish the progression of structural failure and assists the site Survey Group to survey and identify wreckage.
Powerplant Group:This group gathers information and data of powerplants and APU, including the blades, intake ducks, fuel and oil, ignition system, instrument readings, anti-thrust positions, propellers, engine control unit, and fire distinguisher system. The group is also responsible for sampling the fuel and oil to determine whether they had been contaminated. The tasks of this group may be incorporated into the operation of the Maintenance Group, and the Powerplant group can also assist the On-Scene Survey Group to survey and identify wreckage.
Maintenance Group:This group gathers aircraft maintenance data including regular and irregular inspection and maintenance logs, abnormal operation reports, and operational life and circles of structure, powerplants and parts.
Aircraft System Group:This group gathers aircraft systems’ data, which include environment control system, flight control system, hydraulic system, landing gear system, fuel and oil system, electrical system, communication system, navigation system, instruments system, lighting system, pneumatic system, oxygen system, de-icing system, fire distinguisher system, etc. This team should also help Site Survey Group identify wreckage and mark pressurized parts.
Air Service Group:This group collects all factual data and records, including: transcripts and copies of tapes of air traffic control radio transmissions, other communications materials, and radar data. To consolidate the investigation, the IIC may combine the Weather Group, Airport Group, and Air Traffic Control Group and other groups into an Air Service Group.
Weather Group:This group gathers meteorological data including the visibility, cloud ceiling, wind direction and speed; hazardous and unfavorable weather conditions (such as wind shear, thunderstorm, etc.), wet runway, etc. The Weather Group may be integrated into of the Air Service Group.
Recorders Group:This group is responsible for locating and recovering flight data and cockpit voice recorders, and then readout and/or transcribing the recorders data. The group also makes animation of the flight.
Human Factors Group:This group collects relevant data and information about the human physical and psychological conditions and environment factors that may have effect on the occurrence.
Site Survey Group:This group surveys the site of the occurrence and records relevant information such as the location of the wreckage; the marks caused by the aircraft, the positions of impacts and other reference points.
Airport Facilities Group:This group collects all information associated with the airport physical features, obstacle information, visual navigation facilities, visual warning facilities for the obstacles and non-service areas, and airport subsystems, etc.
Survival Factors Group:This group investigates the survival factors of the occurrence, which includes Aircraft crashworthiness, on-board emergency equipment, emergency egress system, and other procedures and equipment pertaining to cabin safety; ground firefighting and rescue operations, emergency medical first aid, and toxicological tests; and injury reports and death certificates, etc.
PR Group:The PR group chairman shall set up PR channel with the media before arriving at the scene. The group should maintain close contact with the Ministry of Communications and Transportation, CAA, and operators in order to provide relevant information to the crew and passengers’ relatives. The group is responsible for the press release and press conferences On-scene.
Wreckage Location and Underwater Recovery Group:If the scene of an occurrence is in the water, the wreckage location could be determined by studying its flight plan, radar track, witness accounts and other relevant information. The Wreckage Location and Underwater Recovery Group shall contact the organizations, which possess underwater search and location capability to assign necessary vessels and aircraft to conduct survey and wreckage location. After the wreckage location is determined, the group will consult with salvage companies about the feasibility of wreckage recovery and decide whether or not to contract domestic or foreign underwater salvage operators to conduct the recovery.

Factual Report

The factual report includes all sorts of factual information, such as records of interviews, aircraft basic data, aircraft damage data, site survey and the contents of flight recorder (black box) and so on. The results of simulations, tests and studies carried out which required by the investigation are also part of the factual report. Each group must complete its group factual report in the factual data collection phase, and the IIC will integrate them into the factual report for the occurrence investigation. This report would be published after the involved parties, including CAA, the airlines and the accredited representative/ aircraft manufacturer, jointly verification of  the contents.

Final Report

Based on the factual data, the investigation team conduct the analyses of probable causes,  risk analysis and proposing the safety recommendations to produce the draft Final Report. If necessary, the IIC may invite relevant parties, such as the CAA, the airlines and aircraft manufacturer, to hold technical review meetings and hear  their comments about the draft report. The draft Final Report would be amended, if comments from parties are adopted. A copy of the formal draft Final Report will be sent to all relevant parties. If the ASC receives comments within sixty days of the date of the transmittal letter, the Council Meeting will review the comments and either amend the draft Final Report to include the substance of the comments received or, if desired by the parties that provided comments, append the comments to the Final Report. The updated draft Final Report will be sent to parties who have comments once again. After receiving the updated draft report, they may submit the written applications to have aural presentation of their comments in the Council Meeting within 15 days of the date of the transmittal letter. The Council Meeting will determine whether or not to accept the stated comments and amend the draft Final Report. After complete all the necessary procedures, the Council will issue the Final Report.

For more information about the investigation procedure, please refer to  the ASC Standard Operating Procedure (only available in Chinese) for aviation occurrence investigation.

  • 本會聯絡人:工程師 劉震苑
  • Tel:89127388-330
  • Email:sherry@asc.gov.tw