Air Accident Investigations: Current Issues and Trends

Introduction

Civil aviation in general, and particularly in the United States, has achieved an enviable safety record over the years, now standing at less than one accident per million departures. This accident rate places aviation among the safest industries in the world. Nevertheless, based on the considerable growth expected in air travel — the current number of 25 million flights per year worldwide is expected to double by the year 2010 — it is not sufficient to maintain existing safety rates, and the need for improved aviation safety is apparent (Sarter & Amalberti, 2000).

Unless the already low accident rate in aviation is reduced even further, the increased traffic volume will lead to an average of 25 accidents per year, with over 1,000 fatalities. Because 70% to 80% of all aviation accidents are considered to involve human error, one promising avenue appears to be investments in a better understanding of, and better support for, human performance and human-machine interaction. This includes improved system and feedback design as well as new forms of pilot training to reduce the potential for errors and their catastrophic consequences.

Although the need for introducing these changes is widely recognized, progress is slow and faces a number of challenges. The economic pressure and competition in the worldwide aviation industry are intense, and manufacturers and carriers are careful not to invest in proposed solutions without guaranteed safety and financial paybacks. In addition, the era of purely national standards and regulations in the aviation domain has effectively ended. Many proposed changes in design, training, or operations need to be accepted and applied worldwide. This need for international consensus slows down, and sometimes prevents, progress.

Yet another obstacle is the fact that some in the aviation industry still consider increased automation to be the solution to, rather than a potential source of, human factors problems. To them, observed difficulties are the consequence of human error rather than symptoms of mismatches between humans, machines, and the environment in which they collaborate. In the post-September 11, 2001 environment, such air accident investigations have assumed new importance and relevance, which directly relates to the problem considered in this study.

Airline operating conditions that may affect aircraft damage severity include flying conditions, phase of aircraft flight, pilot utilization, and type of airline service (Phillips & Talley). Between 1989 and 1997, there was an increase in the rate of accidents caused by ground crew error. Most of these accidents did not result in serious injury or loss of life; rather, they were accidents in which a vehicle such as a catering or fuel truck collided with an aircraft and damaged it, or in which an aircraft was pushed back from the gate into another aircraft that was taxiing past (Oster et al.).

In some cases, these types of aviation accidents may reflect an increase in inexperienced ground crew resulting from the industry's rapid growth following deregulation; however, in other cases, the most probable cause of such accidents is increased ground congestion at many of the nation's airports. Although airline traffic grew substantially in the latter part of the 1990s, airport capacity has grown very little in the past two decades, and the result has been more aircraft trying to operate at the same time in the same limited amount of space (Oster et al.).

Statement of the Problem and Study Overview

Today, an average of once every day there is a safety-related accident, incident, or threat reported in the U.S., with the majority of incidents going unreported. The press usually covers only major accidents that result in total and absolute fatalities.

The purpose of this study was to provide a comprehensive analysis of the relevant literature concerning air accidents and their investigation, in order to identify current issues, problems, and trends that bear further investigation.

The aviation industry represents a strategic component of the nation's security infrastructure, as well as an essential part of the economy. Furthermore, despite the challenges faced by the aviation industry following the terrorist attacks of September 11, 2001, and the escalating costs of energy, the United States continues to rely on air travel for a wide variety of personal, business, and military purposes. In this environment, identifying opportunities for improving current approaches to air accident investigations makes good business sense and represents a timely enterprise that can contribute to the growing body of knowledge.

While air accidents and their investigations were reviewed from different countries, there was a specific focus on the United States.

General aviation indicators such as accident rates, fatality rates, and the distribution of accidents by cause provide important benchmarks for assessing the effectiveness of safety interventions and regulatory policies. A mixed methodological approach was used to examine peer-reviewed and scholarly literature concerning aviation safety in general and air accident investigations in particular, together with a quantitative analysis of the causes and incidence of various types of aircraft accidents and a recapitulation of recent media reports on the same subjects.

Types and Causes of Air Accidents

General aviation is defined as all aviation except that carried out by the military and commercial airlines, and includes personal flying, business flying, instructional flying, agricultural spraying, and aerial photography. The broad scope of general aviation means that it encompasses a wide range of aircraft types, pilot experience levels, and operating environments, each of which contributes differently to the overall accident picture.

Airline operating conditions that may affect aircraft damage severity include flying conditions, phase of aircraft flight, pilot utilization, and type of airline service. Accidents are typically categorized according to their primary cause: pilot error, weather, mechanical failure, sabotage, other human error, and other or undetermined causes. Decade-by-decade data reveal that the relative contribution of these categories has shifted over time, reflecting changes in technology, training, regulation, and traffic volume.

Among the most significant and consistent findings in the literature is that pilot error — whether attributable to poor decision-making, spatial disorientation, inadequate situational awareness, or failure to follow procedures — accounts for the largest share of fatal accidents. Weather-related accidents, while somewhat less frequent, tend to cluster in specific types of operations and geographic conditions. Mechanical failure, though declining as a proportion of total fatal accidents, remains a concern particularly in aging aircraft fleets.