How Are Plane Crashes Investigated?

A pie chart highlighting the key reasons for aircraft accidents.

In 2007, approximately 6.84 flights out of every 100,000 flight hours resulted in a crash, and 1.19 ended up in one that was fatal. Though 2007 was almost two decades ago, these statistics are still relevant, as they represent an aspect of aviation almost everyone ignores: how are these accidents reconstructed for investigation? An aviation accident is defined by the death or serious injury of any person, or if substantial damage is done to the aircraft. They can be systematically explained through scientific analysis of data, physical evidence, and fundamental physics.

Why Do Plane Crashes Happen?

One of the main reasons for aviation crashes is human error. Over half of the accidents recorded are due to human error, with pilots getting the blame. Examples of pilot error include misreading instructions, flying the aircraft at an inappropriate height or speed, failure to communicate with other staff, such as flight control, and delaying the warning signs of emergencies. For example, the Colgan Air Flight 3407 in 2009 was a scheduled flight from Newark, New Jersey, to Buffalo, New York, leaving Newark at approximately 9:18 PM. As the aircraft approached its destination, it entered a stall, which is a rapid loss of lift that causes airflow to separate, usually leading to turbulence. Conditions did not improve, and the aircraft crashed into a residential building 5 miles away from the airport. A report conducted by the National Transportation Safety Board (NTSB) analyzed the flight recorder data and cockpit voice recorder as evidence. They concluded that both pilots were fatigued and did not approach the stall correctly (contrary to their flight training, according to the NTSB). This is an example of a human-caused crash.

Another reason includes mechanical error, such as engine failure. Engine failure usually results from wear of the machinery or oil/fuel problems. Fuel exhaustion implies that the aircraft ran out of usable fuel and is no longer usable. Weather also plays an important role, as if it’s cloudy or stormy, it can make steering and visibility difficult, therefore impairing the pilots.

Events Following a Plane Crash

According to NTSB, which is the primary investigative body when it comes to aviation accidents, its investigative process follows four stages:

•  Stage One: The initial notification and decision to investigate. This stage starts after the board is notified of the accident. If criminal activity is suspected (i.e., terrorism or hijacking), another investigative body will serve as the primary investigator, such as the FBI or local law enforcement.

• Stage Two: On-site fact gathering. This stage requires an investigative team to travel to the crash site, gather data, and determine a preliminary probable cause. The team also spends time gathering vital information outside the crash site, such as interviews, maintenance records, and flight logs.

• Stage Three: Analysis of findings and determination of probable cause. The team pieces together the sequence of events and drafts a report that includes a description of the accident, an explanation, a review of the analysis, and a determination of cause. This report is then sent to Board Members for approval.

• Stage Four: Advocating for the acceptance of safety recommendations arising from the investigation. At this stage, the report has already been published online, and the NTSB works to regulate safety protocols and recommendations.

The crash site is the most crucial evidence. Other key evidence includes impact marks on the terrain or objects, wreckage distribution recordings, witness marks, and photography or videos of the site and wreckage. Since some evidence may deteriorate over time, investigators should conduct an initial search of the crash site soon after the incident.

Which Data Do Investigators Analyze and How?

The reconstruction of TWA Flight 800 from collected debris following its crash in the Long Island Sound in 1996.

Investigators aim to collect as much data on the flight as they can, to be sure in conducting the most thorough investigation they can. The following is a list of all aspects of a crash site that the team wants to collect for the investigation:

• Flight recorder: The flight recorder consists of two parts: the flight data recorder (FDR) and the cockpit voice recorder (CVR). This is known as a “black box”, though this term is a misnomer, due to the actual color of the flight recorder, which is orange. These devices also contain an underwater locator beacon, which can track the location of the aircraft and send signals to satellites. The FDR records 88 parameters of data every few seconds, including the time of day, velocity of the aircraft at any given time, and engine information. The CVR records all conversations held between pilots or between pilots and air traffic control.

• Debris on the scene: Investigators at the accident scene take as many photos as they can. This can indicate how and where the aircraft collided with the ground or another aircraft. If parts are salvageable, they can be moved to a secure warehouse to reconstruct the aircraft for more information on the crash. This can also help investigators determine if any parts are missing and why.

• Air traffic control: Other information could be discovered in the air traffic control activity. This activity is recorded in the CVR, but an interesting instance of air traffic control confusion is a recent crash that occurred at LaGuardia Airport in New York, when an Air Canada flight crashed into an ambulance. Air Traffic Control cleared the plane to land on Runway 4, and a minute later, Air Traffic Control cleared an ambulance to cross Runway 4, leading to a collision. This is why air traffic control data needs to be analyzed as well.

Conclusion

Crashes, for the most part, are understood through science and data. By following a strict protocol, investigators effectively analyze data found in the aircraft (recording and tracking devices) and outside the crash site (interviews, location, etc.). After all the relevant information is analyzed and physical data is reconstructed, a report is drafted with the board’s suggestions and updated safety regulations. This process is important as it allows increased safety in the air and on the ground, preventing more crashes from happening in the future.