Alcohol is a widely used drug, and its abuse is a serious public health problem. Alcohol has many widespread effects on the body, and impairs almost all forms of cognitive function, such as information processing, decision-making, attention and reasoning. Visual and vestibular functions are also adversely affected. The performance of any demanding task, such as flying an aircraft, is thus impaired by the effects of alcohol. Many studies have shown a significant proportion of aircraft accidents associated with alcohol use. Alcohol increases the risk of spatial disorientation, hypoxia and poor +Gz tolerance. Many studies have consistently shown significant detrimental effects of alcohol on pilot performance, both in the acute stages and in the post-alcohol period for up to 48 hours. Even low doses of alcohol can lead to reduced performance. While a pilot may legally fly 8 hours after drinking, the residual effects of alcohol may seriously impair their performance, especially in high workload and demanding situations.

Fuel exhaustion and fuel starvation accidents continue to be a problem in the Australian aviation industry, accounting for over 6 per cent of all accidents between 1991 and 2000. 

Within Australia, fuel exhaustion refers to those occurrences where the aircraft has become completely devoid of useable fuel. Fuel starvation refers to those occurrences where the fuel supply to the engine(s) is interrupted, although there is adequate fuel on board the aircraft. 

The current study investigates the overall rates of factors contributing to and significance of fuel-related accidents between 1991 and 2000. While fuel starvation accident rates have remained relatively stable over the past 20 years, fuel exhaustion accident rates have shown a significant decrease of 29.6 per cent. 

Between 1991 and 2000, there were a total of 139 fuel-related accidents reported to the Australian Transport Safety Bureau (ATSB). 

As a result, 49 lives were lost, with an estimated cost to the Australian community of between $63 million and $127 million (in 1996 Australian dollars).

Australia has an excellent air transport safety record. Major Australian airlines have long been regarded as being among the world's safest, and there have been no fatalities involving an Australian high-capacity jet aircraft. This enviable record is due, in part, to an aviation safety culture that recognises the need for constant safety awareness.

Given the commercial pressures facing international aviation, the events described in this report should be seen as a learning experience for the aviation industry, regulatory bodies, and all organisations concerned with continuing airworthiness assurance.

In December 2000 and in April 2001, a number of Ansett Australia (Ansett) Boeing 767 (B767) aircraft were withdrawn from service because certain required fatigue damage inspections of the aircraft structure had been missed. As a result there was uncertainty as to the continuing airworthiness status of the aircraft. In December 2000 the concerns related to possible fatigue cracking in the rear fuselage of the aircraft, and in April 2001 the concerns related to possible fatigue cracking of the engine strut fitting on the wing front spar.

On 11 January 2001, the Australian Transport Safety Bureau (ATSB) commenced an investigation into the circumstances surrounding the withdrawal from service of the Ansett B767 aircraft as the situation was regarded as indicative of a potential safety deficiencyⁱ. On 10 April 2001 the ATSB investigation was extended to include an examination of the continuing airworthiness system for Australian Class Aⁱⁱ aircraft such as the B767.

Action by Ansett and the Civil Aviation Safety Authority (CASA) addressed the potential risks to fare-paying passengers. Although Ansett was subsequently placed into voluntary administration in September 2001, the ATSB continued a detailed systemic investigation because of the importance of the issues involved, both in Australia and internationally.

The international continuing airworthiness system, like all complex and safety-critical activities, is dependent on robustⁱⁱⁱ systems to maintain high reliability. The circumstances surrounding the withdrawal from service of the Ansett B767 aircraft revealed, among other things, that the reliability of the continuing airworthiness system was threatened by a number of weak defences.

The B767 aircraft type was among the first in the world to be designed and certified under damage tolerance principles. Damage tolerance certification relies heavily on scheduled inspections to ensure continuing airworthiness. The aircraft structure is designed to maintain integrity until any fatigue or corrosion damage can be detected at a scheduled inspection, and appropriate action taken. Therefore, in itself, the presence of fatigue cracks in the Ansett B767 aircraft was not necessarily a cause for undue concern. However, it was critical that there were robust systems to ensure that the required structural inspections were carried out to detect the cracks before they exceeded acceptable limits.

Withdrawal from service of Ansett B767 aircraft in December 2000

Ansett was the sixth airline worldwide, and the first airline outside North America, to operate the B767. Of the nine Ansett B767-200 aircraft, five were first flown in 1983 and two in 1984. The aircraft accumulated a high number of flight cycles^iv because they were mostly flown on comparatively short domestic sectors. Ansett had been working with Boeing on fatigue cracking in the area of the Body Station^v 1809.5 bulkhead outer chord since 1996.

In June 1997, Boeing introduced the Airworthiness Limitations Structural Inspection program^vi for the B767. The program was an essential part of the damage tolerance requirements and was designed to detect fatigue cracking in susceptible areas that had been identified through testing and in-service experience. Ansett staff did not initially recognise that some Airworthiness Limitations Structural Inspections were required by 25,000 cycles and a period of almost two and a half years elapsed before that error was identified. At the time that the inspection program was introduced, some Ansett B767 aircraft had already flown more than 25,000 cycles. In June 2000, further 25,000 cycle inspections were introduced, including in the area of the Body Station 1809.5 bulkhead outer chord. Ansett did not initially act on this.

In December 2000, Ansett senior management became aware of the missed inspections and the aircraft were withdrawn from service on 23 December 2000, despite the high commercial cost to the company. At that time, both Ansett and CASA were of the belief that compliance with the missed inspections was mandatory. Subsequent legal advice indicated that the regulatory basis for mandating compliance with the Airworthiness Limitations Structural Inspections for Australian operators was unclear. On 29 December 2000, CASA issued a direction to Ansett specifically mandating the inspections for the Ansett B767 aircraft.

The ATSB investigation found that the Ansett system for the introduction and scheduling of the B767 Airworthiness Limitations Structural Inspections was deficient and vulnerable to human error. A mistake or omission by one or two people could potentially result in continuing airworthiness assurance being compromised. In addition, deficiencies existed in resource allocation and in the supporting information management systems.

From October 1998, Boeing also issued a series of service bulletins in relation to fatigue cracks in the area of the B767 Body Station 1809.5 bulkhead outer chord. Service bulletins are issued by aircraft, component, or engine manufacturers to provide operators with relevant service information. Not all service bulletins are safety-related, and compliance with a particular service bulletin can only be mandated by the State of Registry of an aircraft.

Boeing initially notified operators that the service bulletin requirements were primarily commercial in nature. It was not until November 2001 that Boeing indicated that the service bulletin dealt with a potentially major safety issue. The FAA had mandated action by US operators in relation to the service bulletin in April 2001.

Any action to be taken by Ansett in relation to the Body Station 1809.5 service bulletins issued by Boeing was complementary to requirements under the B767 Airworthiness Limitations Structural Inspection program. It was the failure by Ansett to appropriately incorporate the required Airworthiness Limitations Structural Inspections, issued in June 1997 and updated in June 2000, into the B767 system of maintenance that led to the withdrawal from service of six Ansett B767 aircraft in December 2000.

Withdrawal from service of Ansett B767 aircraft in April 2001

In March 2000, Boeing issued an Alert^vii service bulletin to detect and repair fatigue cracks in the wing front spar outboard pitch load fitting of the B767 engine mounting strut. Boeing recommended that the work be carried out within 180 calendar days. A revision to the service bulletin was issued in November 2000. In March 2001, Ansett became aware that they had not acted on either the original or the revised service bulletins.

During the period from 7-9 April 2001, inspections revealed cracks in the pitch load fittings of three of the Ansett B767 aircraft and they were withdrawn from service. On 9 April 2001 CASA required that a further four Ansett B767 aircraft be withdrawn from service, pending inspection. Those inspections were subsequently carried out, and the aircraft were cleared to fly.

Deficiencies in the Ansett engineering and maintenance organisation

The ATSB investigation found that similar deficiencies within the Ansett engineering and maintenance organisation led to the withdrawal from service of the B767 aircraft in December 2000 and April 2001. Those deficiencies were related to:

• organisational structure and change management
• systems for managing work processes and tasks
• resource allocation and workload.

However, the investigation found no evidence to suggest that Ansett had deliberately breached airworthiness regulations.

Ansett had undergone considerable change over a number of years. Many of the Ansett systems had developed at a time when the company faced a very different aviation environment. Over time, efficiency measures were introduced to improve productivity but the introduction of modern robust systems did not keep pace with the relative reduction in human resources and loss of corporate knowledge.

Risk management and implementation of change within the Ansett engineering and maintenance organisation were flawed. Inadequate allowance was made for the extra demand on resources in some key areas during the change period.

The Ansett fleet was diverse and the point had been reached where some essential aircraft support programs were largely dependent on one or two people. Hence it was possible for an error or omission by a particular specialist to go undetected for a number of years.

Resource allocation and workload issues had been evident within some areas of the Ansett engineering and maintenance organisation for a considerable period of time. The investigation found that measures aimed at achieving greater productivity had been introduced throughout the organisation without sufficient regard to the different circumstances and criticality of the different work areas. Insufficient consideration had been given to the possible consequences of resource constraints on the core activities of some safety-critical areas of the organisation.

People and robust systems are two of the prime defences against error. Therefore, a combination of poor systems and inadequate resources has the potential to compromise safety. If a failure by one or two individuals can result in a failure of the system as a whole, then the underlying problem is a deficient system, not simply human fallibility.

The Australian continuing airworthiness system

The ATSB investigation found that based on the Ansett B767 experience, the Australian system for continuing airworthiness of Class A aircraft was not as robust as it could have been, as evidenced by:

• uncertainty about continuing airworthiness regulatory requirements
• inadequate regulatory oversight of a major operators continuing airworthiness activities
• Australian major defect report information not being used to best effect.

The investigation identified a need for the regulatory basis for continuing airworthiness requirements of Class A aircraft to be better defined and disseminated to operators.

No evidence was found to indicate that CASA had given formal consideration to monitoring the introduction of the B767 Airworthiness Limitations Structural Inspection program by Ansett from 1997 onwards.

Prior to December 2000, there was apparently little or no awareness among Ansett senior management or within CASA of the underlying systemic problems that had developed within the Ansett engineering and maintenance organisation. The presence of organisational deficiencies remained undetected. In addition, there were delays in adapting regulatory oversight of Ansett in response to indications that Ansett was an organisation facing increasing risk.

The decision by the then Civil Aviation Authority in the early 1990s to reduce its previous level of involvement in a number of safety-related areas did not adequately allow for possible longer-term adverse effects. This included reducing the work done by Authority specialist staff in reviewing manufacturer's service bulletins relevant to Australian Class A aircraft, and relying on operators' systems and on action by overseas regulators in some airworthiness matters.

CASA's central database for major defect reports was incomplete, partly due to deficiencies in reporting, and the information received was not always fully analysed. In addition, feedback to the initiators of major defect reports, and to other operators, was limited. As a result, the potential safety benefit of the major defect reporting system was not fully achieved.

The FAA and ICAO

Delays by the US Federal Aviation Administration (FAA) contributed to a lack of awareness by Ansett and CASA of required B767 Airworthiness Limitations Structural Inspections. This breakdown in FAA process was acknowledged by the US Secretary of Transportation in August 2001. The FAA did not issue airworthiness directives in relation to the June 1997 Airworthiness Limitations Structural Inspection program, or the service bulletins for the Body Station 1809.5 bulkhead outer chord and the wing front spar outboard pitch load fitting, until after the second Ansett groundings in April 2001.

Different views within the FAA as to the importance of airworthiness directives to mandate continuing airworthiness requirements for damage tolerance aircraft types contributed to a lack of timely action by the FAA. The ATSB report includes recommendations that the FAA ensure that such airworthiness directives are processed and released without undue delay, and that affected parties should be informed when delays do occur. The report also recommends that the FAA ensure that the process for determining grace periods for aircraft to comply with airworthiness directives is both systematic and transparent.

The ATSB report outlines where the existing international continuing airworthiness system, as defined by International Civil Aviation Organization (ICAO) standards and recommended practices, could be enhanced by the application of quality assurance mechanisms to the processing and distribution of safety-related information.

The events outlined in this report indicate that there was a breakdown in the continuing airworthiness system within Ansett, the FAA, and CASA. In addition, the possible safety significance of cracks in the area of the B767 Body Station 1809.5 bulkhead outer chord was not initially highlighted by Boeing.

Safety action

On 12 April 2001, the ATSB released two safety recommendations to CASA. The intent of these recommendations was to enhance the robustness of the systems used to manage the continuing airworthiness of Australian registered aircraft such as the B767 by ensuring that:

• action, or lack of action, by another State did not adversely affect the safety of Australian Class A aircraft
• all service bulletins relevant to Australian Class A aircraft were received, assessed and implemented or mandated as appropriate.

CASA subsequently initiated a comprehensive review of its systems to monitor, assess, and act on service bulletins, to ensure that those critical to safety could be readily identified and acted upon appropriately. Recommendations from that review were addressed in an associated implementation plan that detailed the nature and timing of the actions that CASA would take in response to the recommendations. The ATSB is monitoring the implementation of this important safety action.

In response to the circumstances of the events of December 2000 and April 2001, the FAA has included further checks and balances designed to ensure that all service bulletins issued by US manufacturers are properly reviewed and addressed. In addition, the FAA has established an 'early warning system' to provide non-US airworthiness authorities with information on pending occurrence investigations that may result in mandatory action by the FAA.

The manner in which events developed highlights the need for organisations to be continually mindful of potential threats to safe operations. Periodic review is needed to ensure that existing systems for maintaining air safety keep pace with the changing environment.

Implementation by the relevant organisations of the recommendations made by the ATSB as a result of this investigation should help to ensure that aviation systems, both within Australia and internationally, are strengthened and that air safety for Class A aircraft is enhanced.

i Section 19AD of the Air Navigation Act 1920 defines a safety deficiency as any situation related to aviation that can reasonably be regarded as having the potential to affect adversely the safety of aviation.

ii Class A refers to an aircraft with a Certificate of Airworthiness issued in the transport category, or one that is used for regular public transport operations.

iii In the context of this report, a system is robust if, when someone makes an error or a problem occurs for some other reason, the system can detect the deviation and recover without any significant negative effect.

iv A flight cycle is one completed take-off and landing.

v Body Station number is the distance in inches from a datum in front of the nose of the aircraft to a particular point of the aircraft structure.

vi The Airworthiness Limitations Structural Inspections were in addition to zonal inspections and scheduled structural inspections that had formed part of the B767 maintenance program from the time the aircraft entered service.

vii Boeing service bulletins are classified into three categories in order of urgency: Alert, Unusually Significant, and Standard. Alert service bulletins are issued for safety-related issues that require the immediate attention of the operator.

The ATSB has issued three safety recommendations arising from the ongoing investigation into the circumstances in which a Piper PA31-350 Chieftain ditched in Spencer Gulf SA with the loss of eight lives during a regular public transport (RPT) service from Adelaide to Whyalla on 31 May 2000 (Occurrence 200002157). The recommendations relate to mixture leaning procedures and the carriage and use of life saving equipment.

Immediately prior to the accident the pilot gave a MAYDAY report to Flight Service indicating that the aircraft had experienced two engine failures. The investigation found mechanical damage to both engines. The left engine had failed following a fatigue fracture of the crankshaft at the No. 6 connecting rod journal. Cracks of this type are created by the generation of thermal stresses in the journal surface.

The No. 6 connecting rod "big end" bearing had failed, and it was evident that engine operation had continued after the bearing shells had been broken down. The surface of the journal, and the journal radii, had been damaged extensively by the rotation of the journal against the connecting rod. Extensive thermal cracking was evident over the entire journal surface.

In the right engine a hole had developed near the top of the No. 6 piston, allowing combustion gases to bypass the piston rings. The hole had been created by an exposure to temperatures within the melting range of the piston material. There were no failures of any other structural components of the right engine.

The ATSB is examining a number of recent occurrences involving Textron Lycoming TIO-540 series turbo-charged engines, similar to those fitted to the PA31-350. Engineering analysis indicates that the engines had typically been operated at or near peak exhaust gas temperature (EGT).

The fuel mixture leaning practice adopted by the operators during cruise flight was based on EGT settings ranging between 50 degrees (F) rich of peak and 50 degrees lean of peak EGT. While this practice is in accordance with the PA31-350 pilot operating handbook, early results suggest that operations in that EGT range, in combination with other possible factors, may have contributed to induced engine damage due to detonation.

This is in contrast to other operators who have not experienced similar problems and use a more conservative leaning procedure by setting EGT at around 100 degrees rich of peak.

Induced damage may manifest itself through low compression, loss of power, erratic operation, metal contamination in filters or even complete engine stoppage. The underlying reasons for these symptoms can include burnt pistons, stretched or 'tuliped' valves, cracked spark plug ceramics or distressed bearings.

Operators can minimise the likelihood of such damage by eliminating the possibility of detonation. It can be insidious, and a pilot may not be aware that detonation is occurring.

Pending the outcome of its investigation of these issues, the ATSB suggests that, in addition to following the guidance provided in the pilot operating handbook, the operators of all turbo-charged engines avoid high cylinder temperatures through the adoption of a conservative approach to fuel mixture leaning practices.

Civil Aviation Orders 20.11 paragraph 5.1.2 details requirements for the carriage of life jackets for over-water flight. Multi-engine land aircraft authorised to carry nine passengers or less on RPT or passenger charter operations are not required to be equipped with life jackets or equivalent flotation devices unless the aircraft is operated over water and at a distance from land of greater than 50 NM. The Adelaide to Whyalla route was less than 50 NM from land.

Preliminary evidence indicates that the occupants of the Chieftain would have had sufficient time to don life jackets had they been provided. At least two of the occupants may have escaped from the aircraft after it ditched but subsequently drowned. Had life jackets or equivalent flotation devices been available it is possible that their chances of survival would have been greatly increased.

The Australian Transport Safety Bureau has recommended that:

• the Civil Aviation Safety Authority alert operators of aircraft equipped with turbo-charged engines to the potential risks of engine damage associated with detonation and encourage the adoption of conservative fuel mixture leaning practices. [R20000250].
• the Civil Aviation Safety Authority amend Civil Aviation Order section 20.11 paragraph 5.1.2 to remove the restriction that it only applies to aircraft authorised to carry more than nine passengers. [R20000248].
• the Civil Aviation Safety Authority ensures that Civil Aviation Orders provide for adequate emergency and lifesaving equipment for the protection of fare-paying passengers during over-water flights where an aircraft is operating beyond the distance from which it could reach the shore with all engines inoperative. [R20000249].

Every pilot's worst nightmare is the thought of a collision with another aircraft. History shows that it can be just as catastrophic on the ground as in the air.

The industry's worst disaster remains the collision between two Boeing 747s on the runway at Tenerife in 1977, in which 583 people died.

According to the Federal Aviation Administration, the number one aviation safety issue in the United States is now runway incursions, which are occurring at a rate of about 230 a year.

In Australia the figures are a lot lower. The ATSB recorded a total of 89 runway incursions in 1996, 130 in 1998, and 113 in 1999.

Unlike the US, Australia has considerably fewer airports in controlled airspace and less daily traffic movement. But the numbers are significant enough to warrant closer inspection for trends and safety implications.

A runway incursion is an occurrence at an airport with an operating air traffic control tower that involves an aircraft, vehicle, person, animals or another object on the ground, and which creates a collision hazard or results in a loss of air traffic separation.

Using the Systemic Incident Analysis Model, [SIAM was described on page 33 in the last issue of Flight Safety Australia], an analysis of occurrence reports held by the ATSB reveals that the majority of runway incursions involve a failure to follow air traffic control instructions.

Approximately 85 per cent of runway incursions in the period 1997-1999 occurred after the failure of the defence of 'ATS procedures, facilities and standards'. Of the ATS failures, nearly 94 per cent are further classified as 'clearances and instructions' failures. In just over 90 per cent of the incursions, Air Traffic Services noticed the problem, and the situation did not become more serious.

The following example shows how a series of events can lead to a runway incursion, starting with a failure to follow instructions.

On Wednesday 22 July 1998 at Sydney airport a Boeing 737 and a Metro 111 narrowly avoided collision at the intersection of taxiway Juliet and runway 34L.

The Metro pilot was taxiing the aircraft on taxiway Juliet with instructions to taxi via taxiway Bravo and hold short of runway 25. The pilot read back the instructions correctly.

The pilot had experienced difficulties during a practice ILS approach under the supervision of a training captain and was distracted with thoughts of his performance. The training captain left it too late to warn the pilot that he had taxied the aircraft past the correct taxiway turn-off and only called for him to stop when he saw the aircraft landing on runway 34L.

The 737 was landing on runway 34L at the same time that the Metro overshot the runway holding point. The pilot could not stop the aircraft before the taxiway entry point and passed to the left of the runway centre line to keep clear of the Metro. It cleared it by about 25 metres while travelling at 80 knots.

The air traffic controller called for the Metro to stop about the same time as the check captain. The prompt action of the tower controllers was the final safety defence which stopped the aircraft from entering the runway.

Other examples show how incomplete communication and air traffic control actions can lead to a runway incursion.

On 14 May 1999 a Navajo Chieftain lined up on runway 34L at the intersection of taxiway B10 at Sydney at night. A Saab 340 had been cleared to depart prior to the Chieftain. Another Saab 340 was on final approach to land on the same runway.

When the departing Saab had been cleared to take off the arriving Saab was cleared to land. The pilot of the Chieftain was then given a conditional clearance to line-up on the runway behind the landing aircraft. In the same transmission, the pilot was also given instruction regarding the direction of turn and heading to adopt after becoming airborne.

The pilot of the Chieftain heard the line-up clearance and after take off instructions, but did not hear the condition that the aircraft should line up behind the landing aircraft. The pilot read back the instructions that he heard, but the controller did not notice that the condition on the line-up clearance was not read back.

The Chieftain lined up on the runway, sighted the aircraft on final approach to runway 34L, and expected an immediate take off clearance. The crew of the Saab noticed an aircraft on the runway and after contacting the tower commenced a go-round from a height of approximately 35 feet, overflying the Chieftain at a height of about 150 feet.

The controller had correctly issued the take off instruction, but did not detect the incomplete read back by the pilot. The controller did not notice with a normal visual scan or by referring to the surface movement radar that the Chieftain had already entered the runway contrary to its assigned clearance.

System defences

While system defences work by preventing a serious accident on many occasions, occurrence reports will often highlight the potential for a breach in the defences, leading to safety action to rectify a deficiency before it contributed to an accident.

At Perth airport on 9 October 1997 a B767 landed on runway 21 while a B737 was on final for runway 24. Visibility from the tower was poor due to low cloud and fog.

The controller reported that he was unable to see either runway clearly. As the B767 turned off runway 21 onto taxiway J the crew were instructed to hold short of runway 24. They were unable to comply with this instruction as their aircraft was already two to three metres past the holding point for runway 24. They reported their position to the controller who then instructed the crew of the B737 to go round. The B737 was 3 nm from the runway at the time.

The pilot in command of the B767 reported that he had not previously used taxiway J and that in the limited visibility the aircraft had reached runway 24 more quickly than expected. Although they had attempted to stop short of runway 24 the aircraft passed the holding point before all movement ceased.

Had the crew of the B767 not reported its situation immediately there were no other defences to prevent a possible collision between the aircraft.

Key safety messages

While the figures in the Bureau's database represent only those occurrences in an active control zone, they also highlight safety issues that apply to operations at non-controlled aerodromes.

The importance of pilot look-out, clear radio communications and go-round procedures feature regularly as one of the key safety messages, as the following catastrophic accident in the United States shows.

At Quincy Municipal Airport in November 1996 a number of passengers and crew were fatally injured when two aircraft collided at the intersection of two runways.

A Beech 1900C made a straight-in approach in visual conditions to Runway 13. At the same time, a Beech King Air began its take-off roll on Runway 04. Waiting behind the King Air was a Piper Cherokee (PA28).

The captain of the Beech 1900C reported his aircraft was on short final for Runway 13. He asked whether the aircraft in position on Runway 04 was holding or about to take off.

The King Air pilot did not respond, but the pilot of the PA28 did, and stated it was holding for departure on runway four. The US National Transportation Safety Board's (NTSB) report found the PA28 pilot's response to the Beech pilot's question was inappropriate since the PA28 was behind the King Air and not first in line for take-off.

Despite evasive action by the pilots of both aircraft, the Beech and the King Air collided on the ground at the intersection of the two runways. The weather was not a factor and all the pilots involved were properly rated, trained and qualified.

The NTSB determined the probable cause of the accident to be the failure of the King Air crew to effectively monitor the common traffic advisory frequency (CTAF.) Also implicated was their failure to scan for traffic. Contributing to the cause of the accident was the PA28 pilot's interruptive radio transmission. The crew of the Beech misunderstood his message.

In its discussion of the human factors involved in the accident, the NTSB concluded that the radio transmission by the PA28 pilot created some of the confusion that precipitated the accident. The pilot of the King Air was a retired airline captain and known to usually be in a hurry to get home. It is possible the crew in the King Air were not monitoring the CTAF.

Industry safety success

The key to the aviation industry's success in developing into a safe system is its defences. Many elements such as procedures, and hardware and software, play a part in providing a defence against the consequences of human error. When one or more of these system defences are breached, an incident can happen. If they fail, an accident may be the outcome.

The best defences against the hazards of runway incursions are by compliance with procedures, and for pilots to cross check and monitor their environment and actions to maintain situational awareness.

Put yourself in the position of the pilot in the occurrences described above. What would you have done? More importantly, what will you do from now on?*

On the 20th May 1988 at approximately 1609 hours, a Cessna 172 collided with a Piper Tomahawk in the circuit area at Coolangatta, Queensland. The accident, in which four people died, occurred in conditions of good visibility.

This collision and others which occurred in the late 1980s drew attention to the deficiencies of the see-and-avoid concept.

The Coolangatta accident report stated that: 'As a result of this accident, the Bureau of Air Safety Investigation has undertaken to conduct an evaluation and prepare a report on the practicability of the see and be seen (see-and-avoid) principle in controlled and non-controlled airspace.' (BASI report 881/1042).

This report, prepared in response to that undertaking, summarises the research relevant to unalerted see-and-avoid and is intended as a reference document for Civil Aviation Authority (CAA), Industry, and BASI personnel as well as a source of recommendations. The report does not analyse the Australian accident experience.