U.S. Aircraft Accident Investigation Standards

U.S. Aircraft Accident Investigation Standards and Case Study

The accident investigation standards of the U.S. follow the regulations mandated by government agencies such as the NTSB (National Transportation Safety Board) and the FAA (Federal Aviation Administration). These two agencies act as governing bodies that spell out the exact requirements and regulations concerning the investigation of any U.S. crash. They also help to dictate exactly how investigations are carried out, and report on the findings of the investigations after they are concluded. There have been many technological advancements in the field of crash investigation, many of which allow investigators and regulators to better understand the exact circumstances and scenarios involved in the crash as well as the minutes and hours leading up to the crash itself. These technologies have been incorporated into both the aircraft and the investigations in order to more fully understand why planes crash and how these crashes can be prevented in the future. These government agencies along with many U.S. And international air carriers also study the investigation results in order to learn to train their pilots and staff more effectively using real world examples from previous crash investigations.

One of the most commonly-used investigation tools that have become commonplace in U.S. aircraft are the cockpit voice recorders and the flight data recorders. These tools allow investigators to see the last few minutes before the crash from the perspective of the flight crews and also see how the aircraft behaved during this time frame. Each of these devices is mandatory on U.S. aircraft currently, and each offers their own unique advantages for crash investigators (Office of Technology Assessment, United States Congress, 1988). Following an accident, these devices are removed and sent to NTSB headquarters in Washington D.C. For professional analysis.

Cockpit Voice Recorders

Often, these are referred to as the "black box." After a crash occurs, investigators typically find these recorders using signals that are sent out through a "pinger" that is activated by specific g-force sensors (Office of Technology Assessment, United States Congress, 1988). These sensors give investigators an advantage in certain types of crashes which occur over water or in very inaccessible terrain. They allow investigators to home in on the exact location of these recorders. The cockpit voice recorders themselves are complicated pieces of equipment that record certain parameters within the voice interactions of an aircraft. Typically they record the last 30 minutes of cockpit voice conversations, radio transmissions, and internal communications that come from the aircraft (NTSB, 2010). These allow investigators to listen to the digital records that have been saved on the recorders like radio and microphone transmissions as well as engine sounds as they are heard from the cockpit.

Often times these records contain valuable information that can help solve cases where pilot error is involved. It can also help investigators understand the exact human reactions to the circumstances and situations involved just before and during a crash. This technology also allows air carriers and simulator trainers to help recreate the exact conditions before the crash in order to help train future crews in how to handle specific scenarios that may have led to a crash in the past (Wells and Rodrigues, 2004). This is one of the ways in which crash investigation technology is aiding in helping to reduce the prevalence of crashes through training and preparation.

Flight Data Recorders

The flight data recorder is another extremely valuable tool in crash investigations. This device records more than 1000 in flight characteristics and parameters within the aircraft and its behavior shortly before a crash (NTSB, 2010). These parameters include warnings, alarms, sensor information and actual in-flight aircraft behavior. Often, the information provided by these devices is unobtainable by any other means, and can help corroborate information given by crash witnesses or survivors (Kane, 2003). It can also be used as a training aid for future air carrier training programs and simulations as the exact parameters and aircraft behavior can be mimicked in a simulator for these purposes. The flight data recorder also allows NTSB officials to piece together a timeline of events immediately before a crash and to build computer models to help illustrate the parameters and flight characteristics that occurred before and during an accident (NTSB, 2010). This information is often the most important in helping to understand how an accident occurred and how to prevent similar accidents in the future. These recorders are housed in a nearly indestructible box that alerts investigators of its whereabouts using a "pinger" system similar to that of the cockpit voice recorder's. According to NTSB specifications, the flight data recorders and cockpit voice recorders can provide up to 25 hours, or 30 minutes, respectively, of continuous information about the flight. They can also each withstand water pressure of up to 20,000 feet, temperatures of up to 1100 C. For up to 30 minutes, and 3400 G's for up to 6.5 milliseconds (NTSB, 2010).

Other Technology

Besides the direct data and voice recorders contained within the aircraft, the NTSB also has many other technologies that aid in helping to understand the underlying causes of a crash and recreate the specific scenario that occurred before and during the crash itself. Another major tool that the NTSB uses in nearly every crash investigation is computer modeling (Learmount, 2009). This allows investigators to not only visually understand how the aircraft behaved but to predict, using computer models, exactly how an accident may have occurred and how the aircraft structures and technologies would have behaved during this time period (Faith, 1997). This is important in understanding how certain materials behave under stress and in accident situations. Often times, by using these computer models, NTSB investigators can relay pertinent and valuable information to aircraft designers and engineers to help in making aircraft safer in the future.

Through the use of flight simulators, the NTSB can gain valuable insight into how humans react to specific situations and flight characteristics, whether trained or warned for them or not. This allows NTSB investigators to help build probable cause by showing how similarly trained and experienced pilots react to scenarios played out as they happened during an accident (Faith, 1997). Through the use of flight simulator technology, the NTSB can also help air carriers emphasize certain training regulations and changes that need to be made in the post-investigation stages of the accident (Kane, 2003). These changes often come as a result of a crash or investigation and help the carriers to train safer, more effective flight crews for future flights.

The NTSB has exclusive access to many of the nation's more technologically advanced laboratories for expert analysis of crash investigation evidence (Office of Technology Assessment, United States Congress, 1988). This can often include analysis of metal fatigue as well as composite materials and their abilities to withstand certain stresses in the aircraft. Any sort of material analysis is done at these labs, which the NTSB has around the nation. Depending on the specific needs of the crash investigators, labs and experts are available at any time for analysis. Much of the results from these analyses are incorporated into future aircraft design and manufacturing as well.

Investigation Standards and Procedures

Within the NTSB's own guidelines for investigations, it clearly states that, "The recommended procedures are not intended to become obligations of the NTSB or to create any rights in any of the parties to an NTSB investigation or any other persons. Deviation from the guidance offered in these documents will at times be necessary to meet the specific needs of an investigation. However, such deviations from the guidance shall be within the sole discretion of the appropriate NTSB employees and shall not be the prerogative of parties to the investigation or other individuals not employed by the NTSB." (NTSB, 2002). This is a key pieced of information that can be used to understand the procedures associated with any NTSB investigation. Basically it states that the NTSB will use whatever tools or means necessary to investigate at their own discretion. Many crashes and accidents require specific investigation standards and tools, and the NTSB reserves the right to use its own discretion in this area of operations.

The NTSB has a standard operating procedure and related handbook for employees relative to common crash investigation protocol. This handbook, called the "NTSB Major Investigations Manual" calls out the specific regulations and requirements for NTSB involvement in investigations.

The NTSB's field manual (2002) helps to outline a general structure for investigations. This structure includes a "Go Team," which is made up of individual investigation experts who are on call to travel to crash locations and begin an investigation. Once on location, the Go Team sets up a headquarters where they can operate from (NTSB, 2002). This headquarters serves not only as a gathering point for investigators and law enforcement agencies, but also as a place where information and evidence can be brought for initial recovery and analysis. A chain of command or authority also needs to be established in each investigation, which is the NTSB and local authorities' jobs after an investigation is launched (NTSB, 2002). Often times this is done to preserve the evidence and wreckage associated with a crash and in the instances where criminal investigations and evidence are pursued, these chains of command are useful in dealing with the implications surrounding the criminal acts.

A press room and actions involving journalists also take place in this headquarters area. After a crash is investigated, the NTSB prepares statements from witnesses or other pertinent parties in order to formulate a final report (NTSB, 2002). This final report is the synthesis of the entire investigation and includes a "probable cause" as well as detailed information surrounding the circumstances of the crash (NTSB, 2002). The NTSB and the FAA often make recommendations and even policy and regulatory changes after a final report is issued and inferences can be made about causes of the crash.

Recent Crash Investigation and Analysis

The recent air crash in Alaska involving former U.S. Senator Ted Stevens was investigated by the NTSB, just as any air crash involving U.S. aircraft would be. But since the aircraft on which Mr. Stevens and other passengers were flying on was a privately-operated aircraft, it was not carrying either a flight data recorder or a cockpit voice recorder (Voice of America, 2010). This crash, like many other small aircraft crashes in the U.S., represent a challenge to investigators in that they are not able to use such tools to help determine probable cause and reconstruct the moments leading up to the crash itself. This is a major disadvantage in the investigation, but since this crash, like so many others, involved a celebrity, the NTSB was careful to conduct a thorough and discreet investigation.

The aircraft involved in the crash came down in a fairly remote section of Alaska, so access to the crash was very limited (Voice of America, 2010). This hampered NTSB efforts to create a headquarters of operation near the crash itself. Instead, investigators moved much of the crash from the point of impact to a hangar where they could more accurately understand the dynamics and specific circumstances that fed into the crash. Another major help to investigators was the fact that there were survivors who could help to relay the last moments of the crash in order for the NTSB staff to gain insight into exactly what happened, and to help establish probable cause (Voice of America, 2010). The NTSB was able to use reports from other pilots as well as official weather records and reports to help reconstruct the circumstances that could have potentially led up to the crash. They also interviewed other Alaska bush pilots and people who knew more about the experience levels of the pilots involved in the Stevens crash to help understand the human limitations associated with the incident (Voice of America, 2010).