On 4 September 2000, a chartered Beechcraft 200 Super King Air departed

Perth Perth is the capital and largest city of the Australian state of Western Australia. It is the fourth most populous city in Australia and Oceania, with a population of 2.1 million (80% of the state) living in Greater Perth in 2020. Perth is ...

for a flight to the mining town of Leonora, Western Australia. The aircraft crashed near

Burketown Burketown is an isolated outback town and coastal locality in the Shire of Burke, Queensland, Australia. In the , the locality of Burketown had a population of 238 people. It is located west of Cairns and west of Normanton on the Albert Riv ...

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, resulting in the deaths of all eight occupants. During the flight, the aircraft climbed above its assigned altitude. When

air traffic control Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled airs ...

(ATC) contacted the pilot, the pilot's speech had become significantly impaired, and he was unable to respond to instructions. Three aircraft intercepted the Beechcraft, but were unable to make radio contact. The aircraft continued flying on a straight north-easterly heading for five hours, before exhausting its fuel and crashing south-east of Burketown."Plane Crashes in Australia, All Eight Aboard Dead", ''Peoples Daily'', 5 September 2000. Retrieved 1 February 2012
The crash became known in the media as the "ghost flight".
,

ABC ABC are the first three letters of the Latin script known as the alphabet. ABC or abc may also refer to: Arts, entertainment, and media Broadcasting * American Broadcasting Company, a commercial U.S. TV broadcaster ** Disney–ABC Television ...

, 21 May 2003. Retrieved 1 February 2012 A subsequent investigation by the

Australian Transport Safety Bureau The Australian Transport Safety Bureau (ATSB) is Australia's national transport safety investigator. The ATSB is the federal government body responsible for investigating transport-related accidents and incidents within Australia. It covers air ...

(ATSB) concluded that the pilot and passengers had become incapacitated and had been suffering from hypoxia, a lack of oxygen to the body, meaning the pilot would have been unable to operate the aircraft. Towards the end of the flight, the left engine stopped due to fuel exhaustion, and the aircraft crashed into the ground. The investigation report said that, due to extensive damage to the aircraft, investigators were unable to conclude if any of the eight aboard had used the oxygen system. The final report stated that the ATSB could not determine what incapacitated the occupants. A number of safety recommendations were made following the crash.

Background

The aircraft involved in the crash was a Beechcraft 200 Super King Air,

registration Register or registration may refer to: Arts entertainment, and media Music * Register (music), the relative "height" or range of a note, melody, part, instrument, etc. * ''Register'', a 2017 album by Travis Miller * Registration (organ), th ...

VH-SKC,

serial number A serial number is a unique identifier assigned incrementally or sequentially to an item, to ''uniquely'' identify it. Serial numbers need not be strictly numerical. They may contain letters and other typographical symbols, or may consist enti ...

BB-47, manufactured in 1975. The aircraft had about 19,000 hours of service before the crash.Australian Transport Safety Bureau 2001, p. 4. The amount of air passed into the cabin is controlled by

bleed air Bleed air is compressed air taken from the compressor stage of a gas turbine upstream of its fuel-burning sections. Automatic air supply and cabin pressure controller (ASCPCs) valves bleed air from high or low stage engine compressor sections. Low ...

valves on the engines. The positions of the bleed air valves can be altered by the pilot.Australian Transport Safety Bureau 2001, p. 7. According to the investigation report, "The aircraft was not fitted with a high cabin altitude aural warning device, nor was it required to be."Australian Transport Safety Bureau 2001, p. 6. The aircraft was fitted with an

emergency oxygen system Aircraft emergency oxygen systems or air masks are emergency equipment fitted to pressurized commercial aircraft, intended for use when the cabin pressurisation system has failed and the cabin altitude has climbed above a safe level. It consists ...

—an oxygen tank which could supply

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

to the crew through two masks located in the cockpit, and to passengers through masks which drop from the ceiling of the cabin.Australian Transport Safety Bureau 2001, p. 8. Investigators concluded the aircraft was airworthy at the time the crash occurred, and a pilot who flew the aircraft earlier in the day said the aircraft functioned normally.Australian Transport Safety Bureau 2001, p. 12. The investigation report stated that "the maintenance release was current, and an examination of the aircraft's maintenance records found no recurring maintenance problems that may have been factors in the accident."Australian Transport Safety Bureau 2001, p. 11.

Crash

On Monday 4 September 2000,Australian Transport Safety Bureau 2001, p. 1. the Beechcraft, chartered by mining company

Sons of Gwalia Sons of Gwalia was a Western Australian mining company that mined gold, tantalum, spodumene, lithium and tin. It was Australia's third-largest gold producer and also controlled more than half the world's production of tantalum,Perth Perth is the capital and largest city of the Australian state of Western Australia. It is the fourth most populous city in Australia and Oceania, with a population of 2.1 million (80% of the state) living in Greater Perth in 2020. Perth is ...

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

, for the town of Leonora, Western Australia, On board were seven mine workers travelling to

Gwalia Gold Mine The Gwalia Gold Mine is located at Gwalia, a few kilometres south of Leonora, Western Australia. It was originally established by Welsh miners in the late 19th century and Herbert Hoover, the later President of the United States, served as th ...

. The aircraft took off from Perth at 6:09 pm local time (1009

Coordinated Universal Time Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about one second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used ...

(UTC)), and was cleared by ATC to climb to FL130 (). Five minutes later, at 1015, it was further cleared to its

cruising altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

of FL250 (); with an instruction to be at FL160 () by from Perth. The pilot acknowledged this transmission. Five minutes later, at 1020, as the aircraft climbed through FL156 (), it was cleared to

waypoint A waypoint is an intermediate point or place on a route or line of travel, a stopping point or point at which course is changed, the first use of the term tracing to 1880. In modern terms, it most often refers to coordinates which specify one's posi ...

DEBRA. The pilot again acknowledged. At approximately 1033, the aircraft passed through its cleared level, and at FL256 (), ATC asked the pilot to confirm his altitude. "Sierra Kilo Charlie—um—standby," the pilot replied. This was the final spoken transmission from the aircraft, and its climb continued. According to the investigation report, several open-microphone transmissions followed, with the sound of background noise from the engines, a person breathing, "one unintelligible syllable," and "two chime-like tones, similar to those generated by electronic devices." During this time, ATC attempted to regain contact with the pilot. At 1040, the controller called out, "Sierra Kilo Charlie Sierra Kilo Charlie, Melbourne Centre, if receiving this transmission squawk ident."Australian Transport Safety Bureau 2001, p. 36. At 1041, the controller asked again, "Sierra Kilo Charlie, only receiving open mike from you. Would you contact me on one two five decimal two."Australian Transport Safety Bureau 2001, p. 37. Alice Springs ridge

The aircraft continued to climb, and left radar coverage at 1102, passing FL325 (). Thirty-one minutes later, Australian Search and Rescue asked the crew of a business jet to approach the Beechcraft. They reported that it was in level flight at FL343 (), and they could see no movement on the flight deck or in the cabin. However, the conditions made it difficult to observe closely. Two other aircraft which were asked to monitor the Beechcraft intercepted it over the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...

, north-west of

Alice Springs Alice Springs ( aer, Mparntwe) is the third-largest town in the Northern Territory of Australia. Known as Stuart until 31 August 1933, the name Alice Springs was given by surveyor William Whitfield Mills after Alice, Lady Todd (''née'' Al ...

. The pilots reported that it was now in a steady descent, and both aircraft followed it as its

airspeed In aviation, airspeed is the speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: * Indicated airspeed ("IAS"), what is read on an airspeed gauge connected to a Pitot-static system; * Calibrated a ...

increased. The investigation report stated that the pilots observed that "although its external lights were on, nothing could be seen inside the cabin." The investigation report then describes how "the crews of the chase aircraft attempted to contact the pilot of the Beechcraft by radio, but they did not receive a response." At 1510, the aircraft turned left through 90 degrees as it descended through . About south-east of

, Queensland, it hit the ground and disintegrated. The pilot and seven passengers were killed.Australian Transport Safety Bureau 2001, p. 2.

Investigation

The crash was investigated by the

(ATSB), a federal body responsible for investigating transportation accidents in Australia.Australian Transport Safety Bureau 2001, p. v. The final report was published in March 2001.Australian Transport Safety Bureau 2001, p. ii. The report was unable to make a definitive conclusion as to the cause of the crash.Australian Transport Safety Bureau 2001, p. vii. The report found all those aboard the aircraft, including the pilot, had likely become incapacitated and begun suffering from hypoxia.Australian Transport Safety Bureau 2001, p. 26. The report stated, "After the aircraft climbed above the assigned altitude of FL250, the speech and breathing patterns of the pilot, evidenced during the radio transmissions, displayed changes consistent with hypoxia."Australian Transport Safety Bureau 2001, p. 29. Investigators were, however, unable to conclusively dismiss toxic fumes as the cause. "The incapacitation of the pilot and passengers was probably due to hypobaric hypoxia because of the high cabin altitude and their not receiving supplemental oxygen" the report said, adding, "The reasons for the pilot and passengers not receiving supplemental oxygen

rom the oxygen tank aboard the aircraft Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * R ...

could not be determined." The ATSB found it likely that the autopilot was engaged, and this caused the aircraft to fly on a straight heading; the vertical path of the aircraft indicated climb power had been set before the occupants of the aircraft were incapacitated. According to the report, "the design of the aircraft systems were such that, with the autopilot engaged, the engines would continue to operate, and the aircraft would continue to fly without human input until it was disrupted by other events, such as collision or fuel exhaustion." It was suggested that, towards the end of the flight, the fuel tank for the left engine was almost empty. "The near exhaustion of fuel in the left wing tanks may have produced at least one, and probably several, momentary losses of left engine power shortly before all power was lost," the report said. "The aircraft yawed and rolled towards the left engine, as was observed shortly before the aircraft collided with the ground."Australian Transport Safety Bureau 2001, p. 25. The report said due to the damage to the aircraft upon impact with the ground, investigators were unable to conclude if any of the eight aboard used the oxygen system. However, the report stated "The absence of a distress radio call, or an attempt to descend the aircraft, and the likelihood that the pilot did not don his oxygen mask, suggested that the pilot was unaware that the aircraft was unpressurised or depressurising." The passengers, the report added, were also likely not wearing their oxygen masks, as there was no noise recorded on the ATC transmissions indicating they were attempting to assist the pilot. Investigators were not able to determine what caused the depressurisation of the aircraft, but stated likely causes included either an incorrect switch selection due to

pilot error Pilot error generally refers to an Aviation accidents and incidents, accident in which an action or decision made by the Aircraft pilot#Airline, pilot was the cause or a contributing factor that led to the accident, but also includes the pi ...

, or a mechanical failure in the aircraft pressurisation system. The air traffic control recordings suggested it was unlikely that a

rapid decompression Uncontrolled decompression is an unplanned drop in the pressure of a sealed system, such as an aircraft cabin or hyperbaric chamber, and typically results from human error, material fatigue, engineering failure, or impact, causing a pressure vesse ...

had occurred. The report explains how "during an explosive or rapid depressurisation of a pressurised aircraft, however, the noise, pressure changes, temperature changes, and draughts within the cabin would have alerted the occupants that a substantial failure had occurred." The document listed the two main factors in the crash as:

Aural warning

In the aftermath of an incident in 1999 in which the pilot of a Beechcraft Super King Air suffered hypoxia, the ATSB published Report 199902928, and recommended an aural warning be fitted on the flight deck of all Australian Beechcraft Super King Air aircraft.Australian Transport Safety Bureau 2001, p. 27. The flight deck of the Beechcraft Super King Air only has visual warning of inadequate cabin pressure. In the aftermath of the Ghost Flight, the Civil Aviation Safety Authority issued a Discussion Paper and a Notice of Proposed Rule Making (NPRM), both proposing aural warning in the Beechcraft Super King Air and other pressurised aircraft. The outcome of consultation on the NPRM was that the Civil Aviation Safety Authority did not mandate aural warning of inadequate cabin pressure, and this angered the families of some of the victims. Instead, the Civil Aviation Safety Authority issued a notice to owners of pressurised aircraft registered in Australia and recommended installation of an aural warning, but did not make it mandatory. The notice said: "The benefit to your pilots and passengers lies in the reduction in risk of an uncommanded depressurisation leading to an incident or fatal accident. The benefit is much greater than the cost of purchase and installation of one of these low-cost systems."

Coroner's inquest

Ghost Flight memorial, Gwalia, 2018 (03)

The West Australian Coroner, Mr. Alistair Hope, conducted an inquest into the deaths of the eight occupants of the aircraft. The inquest determined that the deaths were accidental, but was unable to determine the cause of the crash. The Coroner recommended an aural alarm system for pressurised aircraft, and a low-cost

flight data recorder A flight recorder is an electronic recording device placed in an aircraft for the purpose of facilitating the investigation of aviation accidents and incidents. The device may often be referred to as a "black box", an outdated name which has b ...

.Ian Townsend, "Coroner criticises ATSB following plane crash", ''ABC-PM'', 12 September 2002. Retrieved 1 February 2012
The Coroner was critical of the poor co-ordination between the ATSB, the Queensland Police, and the

Civil Aviation Safety Authority The Civil Aviation Safety Authority (CASA) is the Australian national authority for the regulation of civil aviation. Although distinct from the government, it reports to the Federal Minister for Infrastructure and Transport. CASA is responsibl ...

(CASA). He also criticised the ATSB for failing to take notes when interviewing witnesses, and for its poor presentation of evidence.

Air traffic control

When the air traffic controller responsible for the Beechcraft received the open-microphone transmissions, he alerted his supervisor that he was concerned the pilot could be suffering from hypoxia. The controller and his supervisor completed the standard checklist which, at the time, did not include a procedure to follow in the case of incapacitation or hypoxia. In the aftermath of the crash, the checklist was changed to "incorporate procedures to be followed by air traffic controllers, when a controller suspects that a pilot has been affected by hypoxia."Australian Transport Safety Bureau 2001, p. 13.

References

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