Introduction
On March 5, 2006, the Civil Aviation Authority of New Zealand received a notification that a Robinson R22 helicopter, which had a registration number ZK-HLC, was involved in a fatal accident (Civil Aviation Authority of New Zealand, 2006). The preliminary report had indicated that the helicopter left Wanaka Aerodrome at about 08:15 for a one-hour scenic flight around Homestead Peak before landing back at Wanaka Aerodrome (Civil Aviation Authority of New Zealand, 2006). There were two people on board, a Canadian pilot and an American tourist. They were expected back at Wanaka at about 09:15. However, at about 09:00, eyewitnesses reported a fire at Homestead Park. Immediately the local authorities received the report, a fire-fighting helicopter was dispatched to the area. The first responders on the helicopter immediately realized that the huge inferno was caused by a helicopter crash. After controlling the inferno, a rescue team arrived at the scene of the accident a few minutes later. They established that no one on board had survived (Civil Aviation Authority of New Zealand, 2006). The Civil Aviation Authority (CAA) commenced an investigation the following day to establish the cause of the accident. The report focuses on collecting physical, technical, and observational evidence for an aircraft investigation, with a specific focus on this particular accident.
Evidence plays a critical role in an air accident investigation. According to Chittum (2017), whenever an accident occurs in the aviation sector, the investigators often focus on determining the exact cause so that similar events can be avoided in the future. Besides the information from the flight data recorder and flight voice recorder, physical, technical, and observational evidence also play a critical role in understanding events that occurred before and during the incident. They provide clues as to the possible chain of events responsible for the accident.
Discussion
The primary goal of an air accident investigation is to gather evidence that would help in making a conclusion as to the cause and ways in which similar cases can be avoided in the future. According to International Civil Aviation Organisation, (2018), air accidents can be caused by pilot error, malfunction of the control system, physical damage to critical parts of the plane, meteorological factors among others. In an effort to make air transport the safest means of movement, each time an investigation has conducted the team of aviation experts often goes beyond identifying the specific factor(s) that caused the accident (Wood & Sweginnis, 2006). They also provide detailed recommendations to the manufacturer, airlines, and pilots on how to avoid a similar situation. The tragic accident involving a Robinson R22 helicopter was a major concern to the local stakeholders in this industry. Although the Transport Accident Investigation Commission did not participate in the investigation process, it monitored the events closely and coordinated with the CAA in defining how to improve safety in the industry.
When a team of air accident and incident experts from CAA, led by Mr. T P McCready, arrived at the scene, they found that the aircraft was badly damaged. In fact, the fire had destroyed the immediate vegetative cover in an area of approximately one hectare (Civil Aviation Authority of New Zealand, 2006). The investigators could not rely on the accounts of the pilot to determine the specific causes of the accident because of the fact that everyone on board had perished in the accident. The team had to rely on evidence gathered at the scene of the accident, information about weather, issues relating to the pilot and his passengers, and any other witness reports. In this section, the researcher focused on identifying evidence that would explain the cause of this accident. The table below is a summary of the fatalities in the accident.
Physical Evidence to Be Collected or Recorded at the Accident Site
The investigators did not have access to flight data recorder or aerodrome information, given the type of aircraft involved in the accident, which could help to establish events that took place minutes or seconds to the impact (Civil Aviation Authority of New Zealand, 2006). As such, the team had to rely largely on the impact and wreckage information. The site of the accident was a remote side of a mountain ridge, which was about 22 nautical miles north of Wanaka Aerodrome (Civil Aviation Authority of New Zealand, 2006). The investigators established that the wreckage of the aircraft was scattered in an area that covered about 25 meters wide and 150 meters long (Civil Aviation Authority of New Zealand, 2006). The cabin, engine, mast, and head of the rotor traveled the furthest distance from the site of the impact (Civil Aviation Authority of New Zealand, 2006).In between the point of impact and the cabin lay landing skids, fuel tanks, and tail boom (Civil Aviation Authority of New Zealand, 2006). The middle section of the rotor blade, shown in figure 2, was found about 1000 feet below the site of the accident. It had a clean tear, which indicated that it was damaged during the impact.
The investigators revealed that the left cabin door showed signs of impact damage on the frame of the window, which was consistent with it being hit by a section of the main rotor blade (Civil Aviation Authority of New Zealand, 2006). It is clear from the image above that the damage was sustained during the accident. The middle section of the main rotor blade, shown in figure 3 below, had large marks that showed consistency with impact damage that had been noticed on the left cabin door. It indicated that the rotor had snapped during the first impact, hitting the cabin door, before breaking. The fresh cuts and scratches confirm that the damage was sustained during the accident and that it was not existing before. Such evidence helps to rule out wear and tear as the possible cause of the accident.
The investigators were able to establish that the upper hinge bracket of the airframe of the left cabin door was twisted before breaking apart. Figure 4a below shows the hinge bracket after it was reassembled. The lower hinge bracket of the airframe had no signs of deformation, as shown in figure 4b. The team was able to reassemble the left cabin door and it fitted into the hinge neatly, showing that it did not suffer significant damage on impact. The physical evidence shows that the left cabin door got detached from its airframe before the initial impact and the investigators speculated that it was possibly caused by the fact that the door was not correctly secured. There was then a slight impact between one of the main rotor blades’ mid-sections and the detached door, which eventually forced the rotor blades out of their normal plane rotation (Civil Aviation Authority of New Zealand, 2006). In such a scenario, it would be impossible to control the helicopter, as it would lose its lift. The evidence shows that the aircraft started a rapid descent before striking the side of the mountain at an angle.
The investigation team also established that the aircraft burst into flames upon impact and slight vegetation within about one hector around the last point of impact was destroyed. Both the pilot’s and the passenger’s bodies were recovered at the site. The coroner stated that the pilot’s body had no fluids that could help in establishing the possibility of him being drunk or high on drugs at the time of the accident. The collected physical evidence played a major role in the investigation. It helped in determining the state of the aircraft at the time of the impact, the manner in which it landed, and the possible force with which it came down. Michaelides-Mateou and Mateou (2016) explain that when dealing with a case where the investigating team has no access to flight data recorder and flight voice recorder, analysis of the physical evidence may help in developing a pattern that may explain events that occurred. The investigators ruled out issues about weight and balance after establishing that the two had no luggage heavy enough to destabilize the plane. Fuel, aircraft registration, and airworthiness were also ruled out during the investigation.
Information on Operations of the Aircraft Pertinent to the Investigation
Information about the operations of an aircraft also plays a critical role in air accident investigation. Chittum (2017) explains that issues such as maintenance of the aircraft, pressure that the management puts on pilots and crewmembers, loading procedures, and security measures put in place by a firm to protect passengers, crew members, and the aircraft must be considered during such investigations. The investigative team realized that the firm that owned the ill-fated aircraft had a valid license to operate in New Zealand from CAA. The aircraft had been subjected to several maintenance procedures before the accident occurred (Civil Aviation Authority of New Zealand, 2006). It was a routine procedure to remove the cabin doors when engineers were conducting maintenance. The records obtained about the latest repairs and maintenance activities showed that the engineers followed standard procedures. The aircraft manufacturers also confirmed that removal of the cabin doors during maintenance and subsequent replacement when repair activities were completed was a common and acceptable practice. However, it was noted that failure to follow the standard practice during the replacement process might be a cause of concern.
The investigators revealed that the pilot who was in charge of the helicopter at the time of the accident had 96.6 flying hours (Civil Aviation Authority of New Zealand, 2006). When that experience is compared with the standard requirements as shown in figure 5 below, it is evident that the pilot was qualified to fly the helicopter as a holder of a private pilot license. However, he was yet to qualify for a commercial pilot license. The investigators concluded that inexperience was not a possible cause of the accident.
Direct Witnesses to the Accident Event and Information Sought
In an air accident investigation such as that of the ZK-HLC Robinson R22 helicopter where the team cannot use a flight data recorder or flight voice recorder, witnesses play a very crucial role. Witnesses of the accident can provide the information that would otherwise be available through these devices. Chittum (2017) argues that information such as the behavior of the pilot before or when boarding the plane, the behavior or the aircraft minutes or seconds before the crash and such other related facts may be used to explain the possible cause of the accident. Investigators would also seek information about the medical condition of the pilot at the time of the accident. Such information can be provided by individuals at the point of the departure, those who witnessed its path and behavior after the take-off, and those who were at or near the crash site.
The investigators indicated that nothing was peculiar at Wanaka Aerodrome where the aircraft took off on the way to Homestead Peak. It was unfortunate that the investigative team was unable to find witness information at the scene of the accident. The remote location of the site of the accident meant that it was less likely for people to witness the accident (Civil Aviation Authority of New Zealand, 2006). The information that would be of interest from these witnesses would be specific events just before the pilot lost control of the helicopter and occurrences afterward before it burst into flames. Once again, the team had to rely heavily on the physical evidence collected at the site of the accident.
Airspace, Terrain, Aircraft Serviceabilityand Meteorology
When conducting an air accident investigation, information about airspace, terrain, aircraft serviceability, and weather also play a significant role in determining the cause. According to Griffin, Young, and Stanton (2015), airspace information helps in determining whether it was safe to take off, land, or take a given route based on the availability of other aircraft using the same airspace. The forest cover where the accident took place was another area of focus. The investigators were interested in determining if the aircraft hit a tree or part of the mountain, which then caused the accident. The investigators were able to establish that these factors did not appear to play any role in the accident that was under investigation. The accident did not happen during take-off or landing and it had nothing to do with mid-air collision.
The serviceability of the aircraft is another important factor. Chittum (2017) explains that the airworthiness of an aircraft is critical when conducting an investigation. It should be in the perfect mechanical and technical condition to ensure that it could take-off, complete its flight, and land without any incidences. The serviceability of the ZK-HLC Robinson R22 helicopter was questionable based on the physical evidence gathered. The investigators revealed the left cabin door must have burst open mid-air, causing it to have an impact with the main rotor. The investigators could not make a conclusion as to whether the initial incident was caused by the mistake of the pilot, the passenger, or a mechanical problem with the door. Ritter, Baxter, and Churchill (2014) explain that weather is another important factor that investigators must consider in such investigations. Storm, strong wind, and poor visibility are some of the factors that may cause an aircraft accident. The investigation conducted by CAA indicated that the accident involving the ZK-HLC Robinson R22 helicopter had little to do with the weather.
Pilot qualifications and experience are other factors that should be considered. According to Griffin et al. (2015), before a pilot can be allowed to take control of a private or commercial aircraft, there must be proof that they have the capacity to control the plane. The level of qualification and experience needed vary from one aircraft to another. Stevens (2014) argues that individuals who lack the capacity to control their aircraft, especially in cases of emergency, often cause some accidents. In this case, the pilot was a holder of a Private Pilot License with flying experience of 96.6 hours. Most of these hours (91.9) were spent on this particular type of aircraft. The medical and pathological analysis revealed that the pilot was not using recreational or medicinal drugs at the time of the accident. Although there were no preserved body fluids available to facilitate an alcohol test, information from friends and close associates showed that he was not an alcoholic.
Information about the passenger would also be important in the investigation. Given that there was also one passenger accompanying the pilot, it was helpful to determine the mental stability of the passenger when coming to a conclusion about the probable cause of the accident. Other than the mechanical problem of the left cabin door and the possibility of a mistake made by the pilot, the investigation indicated it could be likely that the passenger forcefully opened it in a suicidal effort. The passenger was in good health, according to a report that was given by his doctor. However, the medical report also revealed that the 61-year-old man was on medication for high blood pressure. As an American tourist who was, visiting the country for some days it was not easy to determine his history of medications, alcohol use, or incidences when they appeared suicidal.
The investigators were unable to rule out a possibility of a deliberate act by the passenger to sabotage the flight. Bibel and Hedges (2018) explain that physical struggles are often easy to establish if there is a piece of physical evidence. Unfortunately, this was not the case in the ZK-HLC Robinson R22 helicopter accident. The impact destroyed most of the evidence that the investigators would have used to confirm or rule out such an occurrence. The fire then consumed the remaining evidence that the corona and the air accident investigators would have relied on to determine physical activities that went on before the helicopter developed the problem and before it made the first impact. As such, the role of the passenger in the accident remained unclear. Based on the activities that this tourist was involved in within the country and the schedule that he had, it was ruled that chances of him sabotaging the flight were remote.
Conclusion
When conducting an air accident investigation, the complexity, range of the physical, technical, and observational evidence have to be systematically collected before concluding on the cause. The detailed information is needed to avoid similar occurrences in the future. The evidence collected would help the investigators to understand events that happened before the accident, especially the initial incident and a chain of activities that eventually led to the crash. In this case, a team of investigators from New Zealand CAA had to establish the cause of the accident involving ZK-HLC Robinson R22 helicopter. The team did not have a flight data recorder and flight voice recorder that would have helped in the investigation. The fire had also destroyed most of the physical evidence needed. However, analysis of the wreckage and other evidence enabled them to determine the cause of the accident. They established that the left cabin door opened forcefully, hitting the main rotor, causing the plane to stall.
References
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