Finding the cause

Jan 14, 2018 - 8:00 PM

Turbine business airplanes have fewer serious accidents than all other segments of general aviation and are on a par with the airline industry in this regard. But when a mishap does occur, an investigation is launched to determine how it happened and what can be learned to help ­prevent similar future occurrences. Countries with any appreciable aviation activity have federal-level accident investigation branches. In the U.S., the Federal Aviation Administration (FAA) and the National Transportation Safety Board (NTSB) perform official inquiries.

The FAA investigates incidents and accidents that usually involve little or no injury to aircraft occupants or people on the ground and little or no damage to the aircraft. It can issue regulations and suspend airman certificates as a result of its probes.

The NTSB, an independent, non-regulatory agency, investigates accidents that result in serious injury, loss of life, or substantial damage to the aircraft or other property. The Safety Board—which is considered the world’s premier authority in its field and often assists other countries in their investigations—has an exceptional track record. In only a few investigations has it ever failed to determine a probable cause.

An NTSB investigation begins with the dispatch of a “Go Team” to the scene of the accident, where they collect evidence. This involves gathering parts of the damaged or destroyed aircraft; arranging for transportation of the bulk of the aircraft to a secure location; and obtaining air traffic control and cockpit voice recorder tapes, flight recorder data, and statements from witnesses and accident survivors.

Within about three weeks after the crash, the NTSB posts a preliminary report on its website. It contains a general description of what happened, where the accident occurred, weather and wreckage information, and the number and extent of injuries. This report also indicates the aircraft make, model, and registration; the operator’s name; whether the flight was private or a charter; and the name of the NTSB investigator in charge.

The deep investigation process involves separate groups, each of which consists of Safety Board members who are experts in different areas, including weather, air traffic control, cockpit and flight data recorders, airframe, avionics, engines, hydraulics, pneumatics, aircraft performance, and human factors. These groups have the daunting task of analyzing the evidence in hopes of discovering clues as to how and why the accident happened. Sometimes, the NTSB invites outside specialists and experts to assist or observe.

In only a few investigations has the NTSB ever failed to determine a probable cause.

It can take several weeks or months to finish this evidence analysis, follow up on witness statements, transcribe voice and data recordings, and ascertain the accident crew’s flying credentials and pilot experience. Once the NTSB completes all these tasks, it creates and posts on its website a public docket that is divided into the findings from each of the specialized groups.

At about the same time, the Safety Board posts its factual report. This document summarizes in narrative form the facts derived from each of the group’s findings as detailed in the public document. It does not incorporate opinions or draw conclusions about the accident’s cause.

Based on its evidence analysis and the input of testimony, if a public hearing is held, the Safety Board will release a final report containing the probable cause and factors that may have contributed to the accident. At this point, 12 to 24 months have typically passed since the accident.

Once an investigation is complete, the NTSB issues recommendations to the FAA. Recommendations that have resulted in rules that have helped to reduce the number and severity of aviation accidents include those requiring certain aircraft to be equipped with ground-proximity warning systems, traffic alert and avoidance systems, weather-detection systems, and cockpit voice and flight-data recorders.

Besides being the impetus behind requirements to have safety equipment installed, National Transportation Safety Board recommendations are often directed at operational issues.

Case in point: investigations into a pair of 2004 and 2005 accidents that exposed shady practices, illegal operations, murky responsibilities, and poor federal oversight of the air-taxi business. The NTSB believed these were examples of an industry-wide problem, and it made recommendations that ultimately led to proposals for tighter regulations, improved policies, and better federal supervision of the air-taxi community. The Safety Board also advised that it be made clear that brokers—often the first point of contact for passengers seeking air-taxi flights—are not aircraft operators and thus do not have operational responsibility for flights.

The FAA accepted many of the NTSB’s recommendations, but it wasn’t until 2013 that the Department of Transportation issued a notice of proposed rulemaking to turn those recommendations into law. As the NTSB had advised, the proposal would require air-taxi brokers that rely on others to perform flights to disclose the name of the entity that operates the aircraft. In addition, the proposed rules would require air taxis to disclose the names of the aircraft owner and all brokers involved in arranging a flight.

The rules were initially set to be adopted in late 2016 but have yet to be finalized. Nevertheless, today many brokers and providers of on-demand flights attempt to vet aircraft operators, usually via third-party companies specializing in aviation safety audits.

In the 2005 crash and in many prior air-taxi flights, the operator lacked an air-charter certificate  (Part 135) but had entered into a charter management agreement with the holder of such a certificate. Such arrangements created the opportunity to easily hide illegal operations. Amazingly, in the 2005 case, the company without the Part 135 certificate operated for two years before the accident, based on its agreement with the certificate holder and with tacit FAA approval. Despite these findings, the FAA chose not to issue new regulations as requested in the recommendations that stemmed from the accident.

Even with recommendation responses not being acceptable to the Safety Board, the air-taxi community has steadily improved the safety and clarity of its operations. This has resulted from regulatory and advisory materials, charter marketing and competitive forces, outside auditing, and self-appraisal. Jet air-taxi operations are now one of the safest segments of professionally flown turbine business airplanes.    

A Half Century of Investigating Accidents

This year, the National Transportation Safety Board marks its 50th ­anniversary of investigating aviation and other transportation accidents in the U.S. Congress created the agency on April 1, 1967, and just two days later, it started working on its first major case: the Lexington, Kentucky crash of a twin-engine Beechcraft air taxi that killed the pilot and all eight passengers.

Established initially as part of the then-new Department of Transportation, the NTSB replaced the Civil Aeronautics Board Bureau of Safety, which had existed since 1940. But it wasn’t until 1975 that the Safety Board became an independent agency, giving it the freedom to do its job unencumbered by political pressure.

Today, the NTSB annually investigates, on average, 1,600 aviation accidents and major incidents, as well as dozens of highway, rail, pipeline, hazardous-material, and maritime accidents. Over the years, it has released more than 14,500 safety recommendations, of which more than 80 percent have been implemented. Nearly 40 percent of the NTSB’s recommendations and more than 98 percent of its investigations relate to aviation.