Bell Helicopter Co 206B, VH-JVW

1. No-one aboard the helicopter identified the spur line overhead
   the intended touchdown point in sufficient time to allow the pilot
   to avoid impacting the wire.

Risk management options for application during an airborne task
include reducing the consequence and/or likelihood of adverse
events, such as an aircraft striking a power cable. Those options
having the potential to affect the consequence of a wire strike
include:

• the use of helmets and wearing of full-cover clothing by
  aircraft occupants
• installation of wire-strike protection systems
• inclusion of advanced safety harnesses
• appropriate flight following and search and rescue
  procedures.

However, in terms of risk, the consequence of an aircraft
striking a power cable can generally be expected to be severe to
catastrophic. As a result, a large investment is generally made by
involved parties in order to decrease the likelihood, and therefore
risk of a wire strike. That was the case during the 2004 Plague
Locust Control Campaign.

The regulatory requirements affecting aircraft operations below
500 ft above ground level, including in the plague locust aerial
support task, were an attempt to reduce the likelihood of an
adverse event affecting a pilot during those operations. In
addition, the Expression of Interest (EOI) mandated requirements
affecting the acceptability of nominated pilots for employment in
the locust survey task, indicated an attempt by the NSW Department
of Primary Industries (DPI) to further reduce the likelihood of an
adverse event during the locust control campaign. Also, the
establishment by the operator of specific pilot low-level
operations competency requirements defined an additional risk
mitigation strategy that was based on the reduction of the
likelihood of an adverse event in that environment. Both the DPI
and the operator's requirements were in excess of the Civil
Aviation Safety Authority regulatory requirements, and were valid
risk management options for application in the locust survey
task.

It was likely that Rural Lands Protection Boards (RLPBs) relied
on the pilot's competence and experiential requirements of the EOI
when considering the risks affecting their employees during aerial
survey operations. The lack of any local control measure that would
have allowed the Forbes or other control centre staffs to ensure
that the occurrence and other pilots complied with those
requirements meant that the Forbes, and possibly other RLPBs
unknowingly placed its employees in a potentially higher risk
environment than intended. Similarly, the residual risk inherent in
the locust control campaign, including that of a wire strike could
have been higher than initially accepted by the State Council in
order for the campaign to commence.

The emergency nature of the 2004 locust control infestation
resulted in the involvement of DPI and RLPB staff volunteers from
throughout NSW in the locust control campaign. In addition,
operators and pilots from many backgrounds and experience bases
were also involved in that campaign. Those circumstances, together
with the 'living' nature of the Standard Operating Procedures (SOP)
and, in some instances verbal amendment process minimised the
likelihood of the standardisation of airborne techniques and
procedures among those operators, pilots and DPI / RLPB staff. That
was confirmed in this instance by the recent consideration of
whether a survey helicopter needed to land to examine the bands of
locusts and the variation in knowledge of the content and
application of the SOPs among the DPI / RLPB staff aboard the
helicopter.

It was probable that the pilot was unaware of the rear seat
occupants' perceived lack of involvement in the identification of
power cables or other hazards, or communication equipment
difficulties affecting that process. That meant that the
identification of any power cables and other hazards effectively
rested with the pilot and senior ranger. It was likely that, having
drawn the pilot's attention to the wires to the west of the landing
area, the senior ranger applied his concentration to the locust
band in the paddock once the pilot commenced the final stages of
the approach to land. In that case, the identification of the west
to east spur line fell to the pilot. Although unable to be
quantified, there was the potential that the pilot's workload
during the approach to land in the unfamiliar environment adversely
impacted on his ability to detect the west to east spur line. The
result was that no-one onboard the helicopter detected that spur
line.

The abbreviated nature of the pilot's induction meant that the
pilot had to integrate relevant aspects of his low flying training
and previous experience to the specifics of the locust survey task
while carrying out that task. In contrast to the pilot's likely
intimate knowledge of the few power cables in the Kununurra area,
the density of the power cables in the Forbes area, and the
differing environmental and other cues indicating the presence of
those cables, suggested that the pilot would have benefited from a
practical consolidation of elements of the Chief Pilot's brief. The
lack of that practical consolidation had the potential to reduce
the reliability of the operator's low-level
rating/approval/training requirement as a risk management tool.

Depending on respective pilots' ratings and endorsements, there
was a potential difference between survey and spray pilots'
knowledge and skills bases affecting the low-level locust control
operations. Adherence to the DPI SOP meant that, in the event that
a survey pilot did not have an agricultural rating, the pilot may
not be able to contribute effectively to the identification and
communication of low-level hazards and sensitive areas by an on
board ranger or spotter. That could result in the ranger or spotter
unwittingly omitting information that was potentially critical to
the safe application of relevant chemicals by a spray pilot.
Although a spray pilot retained ultimate responsibility for the
safety of that application, the investigation concluded that the
SOP compounded the risk of an unsafe or environmentally unsound
application by a spray pilot.

The SOP requirement for locust survey pilots to fly along creek
and tree lines in order to flush up adult locusts could be
perceived to represent a form of mustering manoeuvre. Unless
included as an individual operator requirement, or an individual
pilot held a mustering approval or had completed low-level
training, the SOP required pilots to conduct those mustering-like
manoeuvres without the benefit of the competency-based mustering
risk controls inherent in the requirements of Civil Aviation Order
29.10. In addition, that procedure placed pilots in an environment
identified by the Chief Pilot as being particularly dangerous with
regard to power cables and other hazards. There was the potential
that the SOP manoeuvre requirement could combine with those
environmental dangers to increase the likelihood, and therefore
risk that a pilot might strike a power cable or other hazard to
unacceptable levels.

This investigation identified the potential for the application
of relevant risk management strategies to reduce the residual risk
affecting a low-level aircraft operation to a level considered
acceptable by that operation's stakeholders. The majority of the
investment in risk management in that environment was found to be
in the reduction of the likelihood of an adverse event. In this
occurrence, the lack of a robust application of existing risk
controls to the locust survey task resulted in the level of
residual risk, including that of a wire strike, being above that
intended by the State Council, and considered by respective RLPBs
when approving the employment of their staff in airborne
operations. The investigation was unable to quantify the
contribution of that elevated residual risk to the development of
the accident.

Sequence of events

At about 1215 eastern summer time on 30 October 2004, the pilot
of Bell Helicopter Company 206B, registered VH-JVW, was conducting
aerial work in support of the Forbes area Plague Locust Control
Campaign (campaign) that was being administered by the NSW
Department of Primary Industries (DPI). Also on board the
helicopter were the local Rural Lands Protection Board (RLPB)
senior ranger, who was seated in the left front seat of the
helicopter, and one RLPB and one DPI staff member who were seated
in the rear cabin of the helicopter.

The senior ranger requested the pilot to land in a paddock in
order to examine a previously unidentified band¹ of locusts. The pilot reported
conducting two orbits of the proposed landing area prior to
commencing the approach to land in a north-easterly direction.
During those orbits, the pilot asked all the occupants of the
helicopter to keep a look out for power cables and other potential
hazards in or around the landing area. However, one of the rear
seat occupants reported the understanding of not being required to
call or report power cables unless it was felt that the pilot had
not seen a cable. While neither of the rear seat occupants reported
the presence of any power cables to the pilot, the pilot and senior
ranger saw a north to south running power cable located on the
western boundary of the paddock. They also noted a westerly spur
line emanating from a power pole located abeam the intended landing
point. That power pole was also supporting the north to south power
cable. No-one aboard the helicopter identified a second spur line
emanating from that same power pole, and tracking to the east and
overhead the intended touchdown point.

The pilot reported that, when at 'low airspeed' and passing
through an estimated 25 ft above ground level (AGL) on the final
stages of the approach to land, a previously unidentified power
cable became caught between the skids and underbelly of the
helicopter. The pilot indicated that he attempted to manoeuvre the
helicopter free from the cable, but that the helicopter pitched 90
degrees nose down and impacted the ground heavily on its nose
before rolling onto its roof. The helicopter came to rest on its
right side, facing back along the direction of approach, and was
extensively damaged. There was no fire. The senior ranger suffered
minor injuries and the pilot and rear cabin occupants were not
injured.

Personnel information

The pilot was appropriately qualified for aerial work operations
in the helicopter, and reported being medically fit, feeling well
and adequately rested. The pilot was not required to wear or carry
any vision correction spectacles, although he reported that he was
wearing tinted sunglasses at the time of the accident. He had about
300 hours low flying experience² at the time he was nominated by the
operator for employment in the plague locust survey task. The pilot
indicated that he had:

• most recently been operating in the Kununurra area
• not previously operated in the Forbes area, or with the
  operator
• no experience in plague locust survey or other operations.

The senior ranger indicated that he had flown in a helicopter
once prior to the 2004 campaign. However, he had carried out an
estimated 15 to 20 plague locust survey flights in helicopters
during the 20 to 25 days preceding the accident. He had attended
in-class locust control training courses that were administered by
the DPI earlier in the year, but had received no experiential
training in accordance with the requirements of DPI Standard
Operating Procedure (SOP) for Australian Plague Locust Control in
NSW number 15.16. Among other requirements, that SOP required that
all DPI and RLPB staff assigned to fly in survey aircraft should
have appropriate experience in detecting bands and directing spray
aircraft. The senior ranger reported that, during the occurrence
flight, his responsibilities included managing the survey task and
acting as an observer.

One of the rear seat occupants had been involved in two previous
survey flights during the campaign, and reported being responsible
for spotting and recording locusts during the flight. That spotter
had attended two brief, in-class training courses conducted by the
DPI shortly before the campaign, but had been given no experiential
training in the detection of bands or direction of spray
aircraft.

The second rear seat occupant had been airborne in a helicopter
once previously during the campaign and had minimal aviation
experience. During the flight, that occupant shared responsibility
for spotting and recording locust infestations. That spotter
reported having attended a DPI workshop prior to participating in
the campaign that examined the identification of plague locusts,
but that no experiential training in relation to the detection of
bands of direction of spray aircraft had been provided.

Aircraft information

Based on the evidence provided to the investigation, the
aircraft was certified, equipped and maintained in accordance with
the regulations and approved procedures. The windscreen was
reported to have been clean, and there was no damage to the
windscreen, or any obstruction that might have adversely affected
visibility from the cockpit. The aircraft was not fitted with, and
neither was there a regulatory requirement for the installation of
a wire-strike protection system³ (WSPS). The Chief Pilot indicated
that he felt WSPS might not have had any effect in this instance
because the helicopter struck the power cable at low speed.

One spotter reported an intermittently operating intercom
system, requiring communication with the remainder of the
helicopter occupants through the second rear seat occupant. The
rear seat belts installation included four-point lap and shoulder
harness seatbelts for each occupant.

Meteorological information

No evidence was found to suggest that the weather conditions
influenced the circumstances of the occurrence.

Survival aspects

Civil Aviation Order (CAO) 20.11 included the requirement for
pilots to orally brief all passengers before each takeoff. The
pilot reported that, while he had briefed the passengers in
accordance with that requirement, the actions in the event of an
emergency and a reliable method for reporting power cables, or
other hazards by the senior ranger and spotter were not discussed.
For example, …wire right 3 o'clock, 300 m, travelling front to rear
(of survey helicopter), etc.

The pilot indicated that he had been wearing a helmet at the
time of the occurrence, and that the helmet visor was in the raised
position. There was no regulated requirement for the senior ranger
or rear seat spotters to be similarly equipped, and no stipulated
minimum standard of flying or personal clothing for those persons
for airborne operations in accordance with DPI or RLPB
requirements. Such requirements might typically include full-cover
clothing, safety boots, etc.

Administration of the 2004 plague locust
infestation

In NSW, the Rural Lands Protection Act 1998 (RLPB Act)
and Pest Control Order Number 6 under that Act declared
the Australian Plague Locust to be a pest and imposed obligations
on the occupiers of controlled land to report locusts on their
lands to their local RLPB and to destroy those locusts. Assistance
could be provided by the relevant RLPB, DPI or Australian Plague
Locust Commission when the destruction of the locusts became beyond
the capability of the individual land owner(s). In addition, the
RLPB Act established a State Council as a corporate body with
responsibility for ensuring implementation by RLPBs of:

• the general policies for the protection of rural lands
• operations in accordance with determinations made from time to
  time at State Conferences or by postal ballot.

The State Emergency and Rescue Management Act 1989
(SERM Act) required the DPI to coordinate the response to
agricultural or animal emergencies with the support of relevant
participating and supporting organisations. The State Agricultural
and Animal Services Supporting Plan Memorandum of Understanding
(MOU) established the DPI and State Council responsibilities for
the preparedness for, and response to agricultural or animal
emergencies. That MOU enabled the DPI to approach the State Council
in order to seek technical expertise, personnel support and other
assistance from RLPBs in agricultural emergencies.

At the time of the accident, there were 48 RLPBs throughout NSW.
Each Board was a statutory authority under the RLP Act and was
constituted for each rural lands protection district. Legislated
RLPB responsibilities included those functions affecting the
protection of rural lands, including the surveying and monitoring
of plague locust infestations on pastoral lands. Should an
infestation be considered to reach a defined density, the relevant
RLPB and DPI determined the appropriate control measure. That was
the case in 2004, when the locust infestation reached plague
proportions in certain regions of NSW.

In response to the expected magnitude of the locust outbreak in
the spring of 2004, the DPI requested through the State Emergency
Management Committee (SEMC) that the locust outbreaks should be
recognised as an emergency under the SERM Act, with DPI as the lead
agency in any emergency response. That was supported by the SEMC
and allowed the DPI to access relevant emergency management systems
and resources. That included a request for assistance from the
State Council to RLPBs from throughout NSW.

In response, RLPBs sought volunteers from among their staff who:
were willing to be involved; could be released from their own
Boards for the agreed period; and had the requisite skills or
experience for the necessary tasks. During the campaign, those
volunteer personnel were under the control of the relevant Local
(locust) Control Centre, while administratively remaining a
responsibility of their respective RLPB.

Aerial control of the 2004 locust infestation was coordinated by
the Australian Plague Locust Commission, with responsibility for
the area west of the Newell Highway and the DPI, east of that
highway. The DPI responsibility included:

• monitoring locust populations and levels of infestation
• implementing particular aerial control measures for application
  in specific areas
• contracting for the provision of aeroplane and helicopter
  services in response to aerial spraying and survey
  requirements
• the purchase and supply of chemicals for airborne and
  ground-based application.

Contractual information

In response to the unpredictable nature of the requirement for
aerial support to assist in activities related to the control of
Australian plague locust and other species, the DPI sought
Expressions of Interest (EOI) from aircraft operators to become
'prequalified service providers' of that aerial support.
Successfully pre-qualified operators were placed on an approved
pre-qualified applicant list, indicating operators' agreement that
their aircraft, pilots and crewmembers would assist with locust
control activities on a 'call when needed' basis.

The submission of an EOI by an operator indicated the operator's
agreement with the Conditions of Contract as set out in section
three of the EOI. Those conditions included that:

• The operator was required to notify the DPI of any variation in
  respect of aircraft and/or pilot information and obtain DPI
  approval in writing for that variation.
• The operator and its employees were suitably trained and able
  to demonstrate current competency. In that regard, an operator's
  Chief Pilot was required to certify that each pilot was rated,
  endorsed and competent to complete plague locust tasking.
• No pilot may undertake any task for the DPI unless approved in
  writing. That was reflected in the contract clauses, requiring an
  operator to obtain that written approval before allowing a pilot to
  undertake aerial support in connection with locust control
  services.

In respect of the operator's interaction with the DPI under
those conditions:

• In response to a post-accident request by DPI, the operator
  provided the pilot's information by facsimile on 17 December 2004.
  There was no measure in place at the Forbes or other local control
  centres to allow local staff to check variations in pilot
  information against a DPI master list of approved pilots prior to a
  pilot commencing locust control work. That was the case with the
  occurrence pilot.
• The Chief Pilot certified the pilot's ratings, endorsements and
  competence for employment in the plague locust task on 29 October
  2004. That certification was not forwarded to DPI until 17 December
  2004.
• There was no control measure in place at local control centres
  to ensure that written approval was given by the DPI prior to the
  occurrence, or other pilots undertaking locust survey tasks.

In addition, the EOI allocated responsibility for the training
of DPI and RLPB staff, and any other person involved in airborne
operations, to the operators of those aircraft. The minimum
requirements for applicants for pre-qualification included that
'pilots engaged or to be engaged by the Applicant must have at
least 50 hours plague locust spraying and/or survey experience as
appropriate' and 'Low Flying approval with at least 500 hours
experience'. In the case of aerial spraying of locusts, pilots were
required to hold a Grade 1 Agricultural Rating and be Spray
Safe-accredited by the Aerial Agricultural Association of Australia
(AAAA). In addition to requiring defined flying experience in
agricultural operations, that rating included an examination to
confirm a pilot's knowledge of the content of the CASA Aerial
Agricultural Pilot's Manual, which stressed the importance of an
agricultural pilot to carry out his or her own airborne inspection
of an area to be sprayed. That was because it was the spray pilot's
last critical opportunity to confirm their hazard map and other
planning details. In the case of locust survey aircraft:

…the pilot must have a general permit for low flying
("Low Flying approval") in accordance with
Regulation 157 of the Civil Aviation Regulations
1988⁴.

During the evaluation of the response to the EOI that was
submitted by the operator, DPI staff identified that, of the two
company pilots initially nominated for the plague locust survey
task, one certified having 18 hours locust survey experience and,
the second pilot, no locust survey experience. Notwithstanding, the
operator was contracted by the DPI as a Pre-Qualified Service
Provider, Locust Control on 13 October 2004.

The Chief Pilot reported having an agreement with an operator
located in the north of WA for the cross-hire of helicopters
between the companies, and short notice cross-employment of pilots.
That was to allow for the movement of those resources in response
to seasonal up and downturns in each company's workload. The
occurrence pilot commenced plague locust survey support work in the
Forbes area while remaining an employee of the WA-based
operator.

NSW DPI / RLPB Standard Operating Procedures for Locust
Control - Effective 16 July 2004

The NSW DPI / RLPB Standard Operating Procedures (SOPs) for
Locust Control established the requirements for aircraft operations
involved in the 2004 campaign. Knowledge of the content of the SOPs
varied amongst those aboard the helicopter. One DPI / RLPB staff
member indicated having read the SOPs, although being unsure of the
requirements placed on locust survey aircraft, while another
confirmed that there were SOPs, but indicated having not read them
comprehensively.

All DPI and RLPB staff assigned to fly in locust survey aircraft
were required to '…have SLC [State Locust Controller] approval to
fly and appropriate training and experience in detecting bands and
directing spray aircraft'. During the investigation a previously
unknown error in the SOP was identified by DPI concerning that
approval. That error included that approval for DPI and RLPB staff
to undertake locust survey flights had always been at the local
level. DPI advice was that at the Forbes Control Centre, employees
were allocated to locust survey aircraft on a weekly basis, and
that allocation was notified to staff on a whiteboard. No written
record was available to confirm staff allocation to the occurrence
helicopter. Subsequent advice from the DPI included that, due to
the nature of the 2004 locust campaign, the SOPs 'were seen as
"living" documents which could be changed if required'. In that
regard, the change in the approval process for employees to fly in
survey helicopters had been conveyed to local control centres
verbally, although the text of the SOPs had not been modified.

The SOP included the potential for helicopter survey of
widespread and sparsely concentrated young (nymphs) or adult
locusts. In the case of nymphs, the initial survey was required to
be conducted at about 1,500 feet AGL. The location of significant
infestations was marked using Global Positioning System (GPS)
equipment and the number and size of the nymphs estimated in order
to identify 'blocks' for subsequent aerial control, including
aerial spraying of identified infestations to complement the ground
spraying campaign.

The SOP included that onboard DPI / RLPB observer(s) 'may
require the helicopter to land so that [they can] verify their
observations' if the nymphs were not 'banding as
normal⁵', or there
was extensive ground cover. It was reported that had been the case
during the occurrence flight, when the senior ranger had decided
that the pilot should land the helicopter in order to prioritise
target bands for spraying the following day. The senior ranger
indicated that there had been recent discussion between local and
other RLPB / DPI staff regarding the need to land a survey
helicopter in order to prioritise bands for subsequent spraying.
The senior ranger was unable to confirm the outcome of that
consideration.

When conducting searches for adult locusts, and in the
expectation that the adult locusts would flush up ahead or around
the manoeuvring helicopter, the SOP required pilots to:

…fly along tree and creek lines and in localised areas of green
vegetation approximately 12 ft (3 m) above ground level and at 30
knots (60 km/h).

Once a target group of locusts had been identified for aerial
spraying, the SOP required the Local Locust Controller (LLC) or
ranger aboard the locust survey aircraft to direct the spray
aircraft to the target using GPS coordinates. The LLC or ranger was
then required to:

• Relay the boundaries of the target to the pilot of the spray
  aircraft. That entailed either:
  
  - the survey pilot flying the boundaries, and the LLC or ranger
  confirming the spray pilot's understanding of the boundaries via
  radio communication; or
  
  - the LLC or ranger verbalising the boundaries via radio
  communication, then observing the spray pilot flying around those
  boundaries.
• Identify and highlight any sensitive areas and hazards to the
  spray pilot. That included environmental and physical hazards, such
  as farm dams and power lines.

The Airfield Controller (controller) was responsible for
coordinating aircraft operations at an airfield or landing area,
compiling and managing Search and Rescue (SAR) logs, etc. That
controller complied with the SOP requirement for the completion of
a SAR - Aircraft Information Sheet for the occurrence
helicopter task. In addition, the SOP required the controller to
follow laid down, incremental search procedures should an aircraft
fail to make a planned radio broadcast indicating normal aircraft
operations or to return to base. The pilot indicated that he had
been transmitting scheduled Operations Normal radio broadcasts at
regular intervals to indicate normal helicopter operations, and the
expected time of the next such transmission by the pilot. The pilot
reported that he did not transmit a distress call upon striking the
power cable. Notification of the occurrence was via a combination
of telephone calls by the pilot and DPI / RLPB staff once clear of
the wreckage.

Regulatory framework

In accordance with Civil Aviation Regulations (CAR) 157, flight
is authorised below 500 ft when clear of any city, town or populous
area and the aircraft is conducting aerial work operations
that:

…require low flying, and the owner or operator of the aircraft
has received from CASA either a general permit for all flights or a
specific permit for the particular flight to be made at a lower
height while engaged in such operations;…

The operator held a Low Level Flying Permit that authorised air
work operations below a height of 500 ft AGL. Those operations were
specified in the company Operations Manual and included aerial
spotting and/or counting of wildlife and other similar tasks on
behalf of landowners or Government
Departments/Agencies/Instrumentalities. In addition, the company
Operations Manual included that pilots in command of company
aircraft carrying out low-level aerial spotting operations
must:

(b) hold an appropriate agricultural rating or mustering
approval or have satisfactorily completed the dual training
specified for the appropriate kind of aircraft in CAO 29.10,
Appendix 1;

CAR 206 lists aerial spotting and agricultural operations as
operations conducted for aerial work purposes. Agricultural
operations are defined as:

…the broadcasting of chemicals, seeds, fertilizers and other
substances from aircraft for agricultural purposes of pest and
disease control.

CAO 40.6 defines the requirements of Agricultural Pilot Rating
Grades 1 and 2. Those requirements include completion of a period
of ground training and a written exam, before carrying out initial
and operational flying training. The operational flying training is
followed by a period under supervision, before the newly rated
agricultural pilot is able to conduct unrestricted agricultural
operations. The Grade 1 rating required a helicopter pilot to hold,
or have held a Grade 2 rating, and to have logged a minimum of 500
hours experience on helicopter agricultural
operations.⁶

Aerial stock mustering is defined in CAO 29.10 as 'the use of
aircraft to locate, direct and concentrate livestock whilst flying
below 500 feet above ground level'. The aeronautical experience
requirements for a pilot to engage in mustering operations include
that the pilot must complete 5 hours low flying
training⁷ and an exam
to confirm pilot proficiency, followed by 10 hours operational
training. The occurrence pilot completed the low flying training
component of that requirement in March 1999.

Pilot induction

The Chief Pilot indicated that the pilot's preparation for the
conduct of plague locust survey support included that:

• On 29 October 2004, the pilot signed as having read the company
  Operations Manual. That indicated the pilot's agreement to operate
  the helicopter in accordance with that manual
• The Chief Pilot conducted a pre-flight brief followed by a 0.3
  hour check flight with the pilot on the morning of the accident.
  The content and duration of that flight was reported to be based on
  the pilot's recency with the helicopter type, and the high degree
  of commonality between the Bell 206B helicopters being operated by
  the company in support of the locust control campaign, and by the
  pilot's company in the north of WA. The primary differences between
  the helicopters included the radio installation and associated
  switches.

The Chief Pilot reported placing heavy emphasis on
identification and avoidance of power cables and other hazards
during the pre-flight brief, and stressing the particular dangers
associated with operating below the tree tops. That was in
recognition of the majority of the pilot's experience being in the
Kununurra area, where the Chief Pilot felt there were not as many
wires compared with the Forbes area. There was no practical
application or review in the check flight of means available to a
pilot to identify power cables and their orientation, or to
demonstrate the difficulties affecting that identification.

In addition, the Chief Pilot indicated that he preferred steeper
landing approaches and departures, because that increased the
likelihood that any power cables might be seen during the approach
or departure. In order to increase the power margin⁸ available for that steeper landing
approach and departure technique, the Chief Pilot's preference was
to restrict the number of passengers carried to no more than two.
Those considerations were developed by the Chief Pilot during the
campaign, and were not passed on to the pilot during the pre-flight
brief or check flight.

Risk management

Australian/New Zealand Standard AS/NZS 4360:2004 Risk
Management (the Standard) defined risk as:

the chance of something happening that will have an impact upon
objectives.

NOTE 1: A risk is often specified in terms of an event or
circumstance and the consequences that may flow from it.

NOTE 2: Risk is measured in terms of a combination of the
consequences of an event … and their likelihood…

NOTE 3: Risk may have a positive or negative impact.

The Standard described risk management as 'the culture,
processes and structures that are directed towards realizing
potential opportunities whilst managing adverse [or negative]
effects'. Residual risk is that 'risk remaining after
implementation of risk treatment'. Options for modifying or
treating identified risks with negative outcomes included:

• influencing the likelihood of a risk, in order to reduce the
  probability of a negative outcome
• changing the consequence(s) of an event to minimise the extent
  of any losses.

RLPBs were required to satisfy themselves that adequate
arrangements were in place to manage risks associated with aerial
survey operations before allowing their employees to undertake
work-related tasks in support of the locust control campaign. There
was no evidence of any guidance, such as the Standard having been
provided to RLPBs to allow their confirmation of the adequacy of
those arrangements. The State Council indicated that, while
low-level survey by any aircraft was a high risk activity, the
adoption of appropriate risk control measures had the potential to
reduce the probability of an adverse incident to acceptable levels.
However, the Council recognised that, even with such risk controls
in place, there remained the residual risk of a serious incident or
accident.

Wire density and the requirement to mark overhead power
cables

The pilot stated that there were virtually no power cables in
the Kununurra area when compared with his locust survey support
experience in the Forbes area. The investigation determined that
the density of the known power cables within a 100 km radius of
Kununurra, excluding in the townships of Kununurra and Wyndham was
one known power cable per 10,476 square kilometres. That
represented three power cables that tracked between the two towns,
and from Kununurra to the Ord River Dam and on to the site of the
Argyle Diamond Mine.

In the Forbes area, that wire density, excluding in any
townships was estimated to approach one known power cable per 10
square kilometres. The pilot indicated that the cable struck by the
helicopter had not been marked on the World Aeronautical Chart used
to navigate to the nominated survey area. He felt that the power
cable had been difficult to see because of the extended spacing
between the poles supporting that cable when compared with the
spacing of the poles supporting the north to south power cable that
was identified on the western boundary of the intended landing
area.

The requirements for the mapping and marking of power cables and
their supporting structures are published in Australian Standards
AS 3891.1 1991 Part 1: Permanent marking of overhead cables and
their supporting structures, and AS 3891.2 - 1992 Part 2: Marking
of overhead cables for low level flying. The general requirements
of those standards were discussed in
ATSB investigation report BO/200404286 and include that, in
general, there is no requirement for the marking of power cables
with a height above terrain or obstacles of less than 90 m. The
power cable that was struck by the helicopter did not require
marking in accordance with either standard.

Technical committees are formed by Standards Australia to
develop and review relevant standards, and comprise a balance of
interested and affected parties that are nominated by generally
national organisations. The aim is that the standards should
include consideration of the views of large, common interest
groups. Organisations that consider they represent a valid,
previously unrepresented interest group are able to nominate for
consideration for inclusion in a committee. A number of aviation
industry associations and other bodies were involved in the
development of the Australian Standards affecting the marking of
overhead power cables and their supporting structures. That did not
include some of the groups and associations normally associated
with a number of agricultural and other low-level operations.

¹ A
'band' was described by a ranger to indicate the presence of
immature, ground-limited locusts. Bands appear as dark, ribbon-like
or patchy marks, somewhat like a tide mark or stain.

² The pilot
indicated that his experience included bird control, some power
line work and telecommunication equipment survey and support work
in the Kununurra area in the north of WA.

³ Equipment
installed on an aircraft to reduce the lethality of an impact with
power or other cables.

⁴ CAR 157
placed a requirement on an operator; it did not directly affect
qualifications required to be held by a pilot.

⁵ One of the
rear seat occupants indicated that, on a hotter day, the locusts
were more active. In that case, the band would be more dispersed
and therefore difficult to interpret from the air in terms of
density, size, etc.

⁶ Experience
for the award of an Agricultural Pilot (Aeroplane) Rating Grade 1
included 1,000 hours agricultural flight time, of which 250 hours
experience was required on spraying operations.

⁷ Including:
avoidance of obstacles; aerial reconnaissance and operational
planning; and the effect of obstacles on operational
procedures.

⁸ The surplus
of power between that produced by the helicopter engine compared to
the power required by the helicopter and its systems during the
approach in the ambient conditions.