Aircraft accident investigations are a process where investigators evaluate and consider the human, mechanical, and environmental factors that could have contributed to the probable cause of the accident. Accident investigations use both scientific processes and detective work to piece together the data to determine the accident’s primary causes and recreate the events leading to the accident.
The overall accident investigation process for the gathering, analyzing, and reporting of information is outlined in an international document called Annex 13 of the Convention on International Civil Aviation. An aircraft accident is defined in Annex 13 as an occurrence in the operation of an aircraft in flight where a person is fatally or seriously injured, the aircraft sustains significant damage or structural failure, or the aircraft goes missing or becomes inaccessible.
Major accident investigations often involve many countries’ governments and input from many aviation industry entities. The principal group in charge of any investigation is the government or appropriate agency of the country where the accident occurred. Investigators from the countries where the aircraft is registered, the airline’s headquarters, and aircraft’s manufacturer are also involved. Countries with citizens killed or seriously injured in the crash may ask to be part of the process.
In the United States, the National Transportation Safety Board (NTSB) investigates every aviation incident in the United States, U.S. territories or in international waters. NTSB investigators are often called on to assist in most international accidents based on their high level of experience and knowledge.
The initial phase of the investigation focuses on obtaining all of the information relevant to the accident. Because major aircraft accidents are infrequent, a number of accidents appear to be similar to others. Investigators must not be misled and must follow the processes and obtain the necessary information for each individual investigation.
Every investigation will have an Investigator-In-Charge or IIC, which is usually an investigator from the lead country’s aviation safety board and is in charge of the entire investigation. Depending on the magnitude of the accident, the IIC may set up a “Go-Team,” which is a group of specialists with a wide range of technical and investigative experience to respond to the scene of the accident and begin the investigation as quickly as possible.
The IIC will set up a base location from which all operations will be coordinated. Local police, fire, security and other first responders will determine the hazards or other dangers that may be present at the crash site and will secure the area and wreckage to ensure the safety of the investigative crew.
The investigators examine, photograph and videotape the wreckage and collect as much physical evidence as they can, especially the onboard data and voice recorders. The parts of the wreckage that can be salvaged are usually moved to a secure facility where the investigators later reassemble the aircraft to assist in determining the causes of the accident. If there are accident victims, forensic teams and medical examiners will analyze the remains to identify them and to examine the injuries they suffered.
Investigators will collect evidence regarding issues in areas such as prior aircraft mechanical failures, maintenance records, pilot experience and training, human factors, air traffic control activity, weather conditions and any other evidence that might have contributed in any way to the accident. Interviews will also be conducted with eyewitnesses, survivors, first responders and anyone else that can give the investigators clues to the moments just before and after the accident.
Once the investigation is completed, each investigative group will write a report regarding their findings and analysis of the accident. The lead group compiles the various reports into a single, final accident report. In most cases, the reports are public knowledge and members of the public can search specific accident reports to find out the details of the accidents.
Accident reports are widely used in the aviation industry from government agencies, aircraft and engine manufacturers, airlines, air traffic controllers, and flight and maintenance crews. Safety recommendations in the reports have led to significant improvements in aircraft crashworthiness, numerous life-saving technical advances and improved safety regulations to prevent future accidents and improve flight safety for everyone.