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by A. W. K. Senaratne

One of the most talked and feared topics in the world today is aircraft accidents. This topic gets its prominence from the colossal loss of lives and property this event entails. With the brutal suicide attack on 11th September, 2001, in the United States of America, the problem became more focused due to its complexity and demanding nature.

Maximum attention is being given and large amount of funds is being allocated for work in connection with prevention of aircraft accidents in the Civil Aviation. This problem is tackled in varied ways by many organisations and institutions funded by governments, manufacturers, operators and international bodies and the like. The premier organisation that handles this task is the International Civil Aviation Organisation (ICAO) which is located in Montreal, Canada. 'Safety' or 'Prevention of accidents' is the most important aspect of aviation, which necessity has to be addressed with affordable cost and not at any cost as believed by some.

In general terms an 'Aircraft Accident' has taken place, if due to the operation of an aircraft, a person is fatally or seriously injured or the aircraft sustains major damage. Any other minor occurrence associated with the operation of an aircraft, which affects the safety of operation, is termed as an 'Incident'.

Aircraft Accidents are caused due to several factors and in the field of Aircraft Accident Prevention they can be grouped into three main divisions as follows:

(a) Machine

(b) Man

(c) Environment

In the early days of air travel, Machine or the Mechanical Construction of the aircraft itself was the main cause of a majority of aircraft accidents. In the very early days of flying it was so dangerous to fly and in the western world there was a belief that 'Only Birds and Fools Fly'. The first casualty of an aircraft accident was one of the Wright Brothers himself who invented the aeroplane. Thus, aviation was a risky business right from the start. Naturally, in the early days of aviation, highest emphasis was placed on the machine so as to improve its reliability and thereby to prevent accidents.

The method adopted was to enforce strict rules and regulations in the construction of aircraft structure and its engines and in the operation of it. This approach paid dividends and the number of accidents as against the number of flights greatly reduced. However, different countries having different standards and regulations became a problem. As a consequence, enormous difficulties were encountered in aircraft operations from a country to another.

To overcome this, in 1944 the government of United States of America invited 55 countries to discuss problems in civil aviation and to formulate a set of International Standards, Practices and Regulations to enhance safety of aircraft and facilitation of operation. Representatives of these countries met in Chicago and after weeks of discussion they agreed on a set of rules and regulations on all aspects of civil aviation.

A Convention comprising 96 Articles was signed. This Convention is commonly known as the 'Chicago Convention'. This Convention led to the formation of the Body known as the International Civil Aviation Organisation (ICAO). The vision of this body is to help all member countries to achieve and maintain the agreed Standards and Practices in aviation for the safety and betterment of the aviation industry and to improve these standards as and when required.

All these efforts have reduced the number of accidents from late forties to eighties. The reduction of fatalities (accidents) per year is graphically shown in Figure 1. The vertical axis shows the number of fatalities per year divided by 100 million passenger kilometres (number of passengers multiplied by the number of kilometres flown in each flight and added for the whole year). As evident in the graph, by 1970 the graph levelled off without reaching the zero mark. The number of accidents due to failure of the machine became minimal but the accidents due to the other two factors, Man and Environment remained static.

From the late seventies, accident prevention groups started to study the aspect of man that cause aircraft accidents, as it was evident that the major number of accidents were due to Pilot error. Also the involvement of man in aircraft operation such as Flight Crew (the most involved) followed by ground crew and Air Traffic Controllers etc. are considered as the 'Man' involved that can cause accidents. Hence, the most talked of phenomena in aircraft accident studies is the Human Factor, which is a complex and lengthy subject. The human being is the most flexible, adaptable and valuable part of the aviation system.

Yet it is the most vulnerable to outside influence which can adversely affect the performance of aircraft to cause accidents. An understanding of the Human Capabilities and Limitations and the application of this understanding in the prevention of aircraft accidents are the elements of Human Factors in aviation. This also could be defined in a more simpler manner as the study of the interaction between human and the aviation environment which consists of tools, equipment, instruments, systems and the vehicles they use in the performance of their job.

The term 'Pilot Error' is of no help in accident prevention. It indicates 'Where' the breakdown in the system occurred but it does not provide guidance as to 'Why' it occurred. Furthermore, the term 'Pilot Error' allows concealment of the underlying factors, which need to be brought out if accidents are to be prevented. During Pilot training, a student learns mostly about the mechanical aspects of the machine he flies, Navigation. weather etc. but little emphasis or information is provided to him concerning his own behaviour, limitations, vulnerabilities and motivations. Man is naturally reluctant to admit his limitations for a variety of reasons and also reluctant to give correct information due to fear of job loss, blame, liability etc.

In fatal accident that occurred in the recent past in Sri Lanka, the aircraft had been flying without the required minimum amount of fuel as per safety standards. The required minimum fuel as per safety regulations is the normal fuel requirement for the destination plus the fuel required going to the alternate airport in case the destination airport is closed due to an emergency, plus fuel for another thirty minutes of flying. However, these aircraft had been flying all the time without this minimum fuel requirement.

This hazardous condition had been dormant until one day the weather god broke loose and caused a heavy downpour for over one hour accompanied by thunder and lightning at the Katunayake airport, preventing the aircraft from landing. This hazardous condition combined with few other hazards formed a 'Chain Link' to cause the fatal accident. The aircraft ran out of fuel on the third attempt to land and crashed on to a few houses close to the airport killing three on ground and seven on board. Only the co-pilot survived in the crash. Had they carried sufficient fuel they could have diverted to the alternate airport at Male or they could have circled for a few more minutes and landed safely at Katunayake as the rain seized a few minutes later.

This hazard could have been detected and eliminated had there been a safety audit of the operator by the regulatory authority, the Department of Civil Aviation, thus preventing the fatal accident, which claimed ten lives and many millions worth of property.

In the current accident prevention process, numerous methods are used to identify the Hazards lying dormant in many systems. These Hazards Identification Methods can be grouped as follows:

1. Accident/Incident Investigation

2. Safety Audits of Operators by the Regulatory Authority

3. Safety Programs conducted by Airlines and Airports

4. Other sources of Hazards information.

The prime objective of current aircraft accident investigation by the Civil Aviation Departments or Authorities world over is not to find who is at fault and punish but to prevent further accidents by the identification of Hazards and making recommendations to eliminate them. Hence the investigation of accidents prove futile unless and until the recommendations are implemented. It is a requirement stipulated by the ICAO that the reports so compiled should be published as it gives all the related shortcomings and recommendations for remedial action. Further, the aviation community comes to know the Hazards, which they themselves will correct to the extent of their capability. Also the air travellers and the general public has a right to know what went wrong.

Approach and landing phase is the most critical part of the flying operation. Majority of accidents occurs during this phase of the flight. It was found that most of the disasters occur due to Controlled Flight In-to Terrain (CFIT). This is a phenomenon where the pilot is in full control of the aircraft but unfortunately they fly unknowingly into high ground, water or land short of the runway. This discovery was the watershed for the introduction of the important accident prevention unit in mid seventies, known as Ground Proximity Warning System (GPWS). This avionics system gives a timely warning to the pilot, if the aircraft unusually get close to the ground during the landing phase.

Introduction of this system brought about a remarkable reduction of CFIT accidents. However this system alone did not bring down the accident rate to expected levels. In a further study up to 1992, it was revealed that eighty percent of the casualties of transport category are still due to the accidents during the landing phase of which, CFIT has the most number. Again it was found that human error (pilot or air traffic controller) is the main responsible factor. Many studies are being done in this sector including Human Factor analysis. One of the outcomes is the introduction of CFIT checklist to be carried out by pilots during the landing phase.

In the recent past another important electronic accident-prevention system, was introduced to avoid mid air collision of aircraft. This system is known as the Traffic Control and Alert System (TCAS) or Airborne Collision Avoidance System (ACAS - European). This system gives a timely warning to the pilot of the impending aircraft collision and advice on how to avoid the disaster. It works in conjunction with the Air Traffic Control (ATC) Transponder installed in the aircraft. The ATC Transponder of each aircraft emits radio signals all the time with information of altitude, identification etc.

The ACAS computer analyses the received ATC-Transponder signals of other aircraft in the vicinity and evaluates the possibility of a collision. If there is a possibility, it immediately informs its pilot as well as the pilot of the other aircraft through its ACAS computer for one aircraft to climb and the other to descend to avoid the accident. In the recent Mid-Air collision of a Russian aircraft carrying school children on a holiday and a cargo aircraft over Swiss airspace, it was revealed through the cockpit voice recorder (CVR), that the ACAS computer had commanded the Russian aircraft to climb to avoid collision but the Air Traffic Controller had commanded the pilot to descend. The Russian pilot had obeyed the human command and ignored the computer command which resulted in the collision (human factor).

With all these enhanced preventive methods in operation, still aircraft accidents occur all over the world. Nevertheless, air transport is the safest mode of transport in the world today, when compared with the number of fatalities and the distance travelled. Yet there could be improvements made in number of ways and the concerned aviation community relentlessly pursues to achieve the goal of accident free operation. With the brutal suicide attack in America on September 11th 2001, the whole concept took a severe blow.

However the general opinion of the aviation community is that suicide attacks are not considered as Aircraft Accidents but as a separate subject. Still the suicide attack would come from the crew itself as in the case of Egypt Air Flight 990 from New York to Cairo, where the co-pilot did a suicide nose dive that made the aircraft to disintegrate in air due to excessive speed and crash. The subject is more complicated now. This type of suicide attack could be prevented with further development of aviation safety measures where there will be an electronic device to monitor the brain waves of each passenger including the crew, by having a 'dog tag' tied to each individual which will transmit any unusual excitement of an individual to be monitored by the unit and alert the cockpit crew. This could be a reality in the near future.

(The writer is a Commonwealth Expert on Aviation and has investigated over twenty Aircraft Accidents, Civil as well as Military and was an Assistant Director of the Department of Civil Aviation on Airworthiness and Accident Investigation).

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