History of the flight
At about 1703 EST, aircraft operating north of Gladstone reported receiving an emergency locator transmitter (ELT) signal. Shortly afterwards, a satellite detected the signal, and at 1755 the Australian Search and Rescue organisation (AusSAR) established that the signal was originating from an area near Hixson Cay, on the edge of the Great Barrier Reef, about 150 NM northeast of Rockhampton. At 1900, a fixed-wing aircraft tasked by AusSAR departed Rockhampton to locate the source of the ELT transmission.
At 1953, the captain of a fishing vessel reported that he was communicating with the crew of a yacht who reported that the yacht was sinking. At 2006, the crew of the aircraft tasked by AusSAR reported locating the yacht and its two occupants. The crew also reported that the yacht's life raft had drifted away and that retrieval of the crew by the fishing vessel was unlikely due to the proximity of the reef. Nineteen minutes later, AusSAR received further reports from the crew of the aircraft that the yacht was in danger of sinking.
At 2055, AusSAR requested the availability of a Rockhampton-based rescue helicopter (Rescue 407) to assist in the rescue of the two people stranded on the yacht. The helicopter was only equipped for flight under the visual flight rules (VFR). The duty pilot advised AusSAR that he would not be able to recover the yacht's crew at night, but after confirming the weather details and planning the mission, he agreed to drop a life raft to them. He subsequently called in the duty crewman, who was employed as a paramedic and was a volunteer crewman with the helicopter rescue service.
AusSAR also sought the assistance of an instrument flight rules (IFR) capable helicopter, a Bell 412 (Rescue 500) from Brisbane. Rescue 500 departed Brisbane at 2115 and arrived at Heron Island at 0015.
The Rescue 407 crew refuelled the helicopter to full tanks and loaded several Jerry cans of fuel into the locker located behind the helicopter's cabin. The pilot reported that to hold fuel reserves for the required alternate airfield at Gladstone he had planned to land the helicopter at Hixson Cay to refuel from the Jerry cans. Hixson Cay was about 4 minutes flying time from the stranded yacht's location. Rescue 407 departed Rockhampton at about 2145, arriving on scene at about 2250. The fixed-wing aircraft that had been in the search area since 1945, departed for Rockhampton at about 2157.
The Rescue 407 crew reported that during the transit to the search area at 7,000 ft, they conducted the operator's standard over-water passenger briefing and the intentions for descending to locate the yacht. The pilot was occupying the right side cockpit seat and the crewman occupied the cabin seat next to the left cabin door. The pilot reported that he briefed the crewman that he intended to descend to 50 ft and hover-taxi past the yacht at about 25 kts keeping it on the left side of the helicopter. The crewman was to drop the life raft short of the yacht and then drape a 100 ft length of rope that was attached to the activation line of the life raft across the yacht for its crew to haul in the life raft.
The pilot reported that when he arrived on scene, he initially tracked towards the yacht at 1,500 ft, from west to east along the line of surf breaking on the edge of the reef, but he could not see the yacht in the white water of the surf. He attempted a number of approaches before changing the approach direction so the helicopter was tracking from south to north, at right angles to the reef. The pilot reported that during the last pass, he saw the yacht about 1 NM from the helicopter and commenced descent from 1,500 ft.
The pilot stated that he had initially set the Radar Altimeter (RADALT) altitude warning to 200 ft and after the helicopter had descended through that altitude, he reset the warning to 50 ft. When the helicopter was about 600 m from the yacht, the crewman called the RADALT as passing through 200 ft then 150 ft. On this call, the pilot reduced speed to 50 kts and noted that the rate of descent was 700 ft per minute. During the latter stages of the approach, the pilot's attention was directed totally outside, using the searchlight set to maximum beam width for external illumination. He was satisfied that the approach was progressing well. The crewman then called 50 ft and very soon after, the helicopter impacted the water. The pilot stated that, at the time the helicopter was flying at about 45 to 50 kts. He had not issued any instructions to the crewman to open the door or deploy the life raft. The crewman reported that he estimated the helicopter to be about 400 m from the yacht when he called 50 ft and that the pilot said, "good" before, "everything went black."
Both the pilot and crewman reported that the helicopter was operating normally before it impacted the water. The crewman said that both cabin doors were closed prior to impact.
The helicopter came to rest submerged inverted. Although both crewmembers were initially disoriented and the pilot experienced difficulty in escaping, both crewmembers successfully exited the helicopter. The pilot, who had not inflated his life jacket, returned to the helicopter soon after and retrieved the life raft from the cabin.
At about 2345, the fishing vessel lost contact with Rescue 407. Rescue 500 was tasked at 0038 to also search for Rescue 407, arriving on scene at 0140. During their approach to dispatch a life raft to the yacht, the crew of Rescue 500 saw the inverted helicopter and the associated life raft nearby. Rescue 500 dispatched a life raft for the yacht crew and then departed for Heron Island to await daybreak before attempting a rescue. Just after daybreak, Rescue 500 recovered the yacht and Rescue 407 crews.
The pilot held a Commercial Pilot (Helicopter) Licence, a night VFR Rating (Helicopter) endorsed with Non-Directional Beacon (NDB), a current Grade 1 Flight Instructor Rating (Helicopter), and an expired Command Single-Engine Instrument Rating (Helicopter). The pilot was endorsed on the Bell 407 helicopter type. At the time of the occurrence, the pilot had accumulated a total of 9,593 flying hours, including 46.6 hours on type. He had flown 44.6 hours in the previous 90 days, including 41.6 hours on type and 16.4 hours at night.
The pilot reported that he had significant prior search and rescue experience, conducted in several helicopter types. He also reported that he had flown over 600 retrieval missions with a high percentage at night. In particular, the pilot commented that he had performed many missions to the small cays on the reefs at night without incident. The pilot said that he had completed Helicopter Underwater Escape Training (HUET) when he was in the Australian Defence Force, which was over 5 years prior to the accident. The pilot had not completed Crew Resource Management (CRM) training during his tenure with the operator.
The pilot held a current Class 1 medical certificate with a requirement to wear corrective lenses for distance vision and to have reading glasses available. The pilot's 4-day history leading up to the accident revealed irregular sleeping patterns but he had obtained sufficient sleep over this period. The pilot reported no physiological or medical condition that was likely to have impaired his performance, and that he was adequately rested and medically fit for the flight.
The crewman was employed as an ambulance officer, as an Advanced Care Paramedic and served as a part-time crewman with the helicopter rescue service. He had been part of the rescue service for 2 years but he had not undertaken HUET training or Crew Resource Management (CRM) training.
The Bell 407 helicopter was equipped and certified to operate Day and Night VFR. It was not equipped with helicopter flotation equipment, automatic stabilisation or automatic pilot systems, nor was such equipment required by regulation. It was equipped with a 'Nightsun' searchlight.
The helicopter was fitted with a Bendix King KRA 10A radar altimeter receiver/transmitter unit and a KI 250 indicator. The indicator unit displayed height directly above the surface beneath the helicopter using a needle and dial-type analogue display. The 8.28 cm dial displayed height from 20 ft to 2,500 ft, although published specifications only assured accurate indications between 50 and 2,000 ft.
Following the accident, the Bureau of Meteorology (BoM) provided the ATSB with an estimate of actual weather conditions at the accident site at 2330. The estimates were based on synoptic patterns and meteorological information for Gladstone. The BoM assessment indicated that visual meteorological conditions (VMC) would have existed at sea level with wind from 120 degrees true at 10 knots, no precipitation, good visibility, scattered cloud with a base of about 2,000 ft and some cloud at mid-levels.
The pilot reported that he was advised by the Meteorological Office at Rockhampton airport that the weather at Rockhampton and the area seaward of the coast would be fine with no cloud all night. The pilot did not report flying through cloud during the descent from 7,000 ft.
The pilot of the fixed-wing aircraft that had been dispatched to locate the ELT prior to the arrival of Rescue 407 reported that the visibility was good, with clear sky and that it was a dark night with only a small sliver of moon visible. The pilot returned to the area at about 0230 and reported that the weather conditions were similar to that observed earlier in the evening.
Astronomical data indicated that the moon was waxing crescent with 13 percent of the moon's visible disk illuminated. The moon set at 2025.
The crew of Rescue 500 reported that, while enroute to the search area, there was broken cloud at about 2,500 ft, no moon, extensive sea haze, and poor visibility.
Night VFR operations
There were no aviation regulatory requirements for pilots to consider the amount of external visual reference that was likely to be available for a flight conducted at night under VFR, with the exception of considering forecast cloud below the lowest safe altitude. The pilot was not required by the regulations to consider the amount of celestial illumination, amount of terrain lighting, and/or the presence of a visual horizon. Aviation weather forecasts did not provide information on the amount of celestial illumination nor were they required to do so. This information, however, was available from a variety of other sources.
There was no regulatory requirement for the night VFR rating competencies to be demonstrated during regular flight reviews or otherwise at recurrent intervals. There was no requirement for the holder of a night VFR rating to have demonstrated any recent instrument flying proficiency prior to conducting a flight at night.
When the helicopter wreckage was sighted from the air during the following morning, it was reported as being located about 200 m from the yacht, at an angle to the reef. A straight-line debris trail lying on the sandy seabed was visible through the shallow water. The salvage crew reported that the helicopter's initial impact point appeared to be 600 m south-southwest of the yacht on the reef edge with the debris lying in an approximate straight line between the two points.
The main transmission and remains of the main rotor were lying in an area of breaking surf just near the initial impact point and were not recovered during the salvage. The water depth at the point of impact varied between about 0.6 m and 1.8 m depending on the tide and the sea state.
The tail boom was broken in two places, with the mid portion recovered from deep water northeast of the reef.
An inspection of the helicopter components revealed that the tail rotor drive shaft had been severed by twisting in the direction of normal rotation at a position forward of the oil cooler fan. The tail rotor gearbox housing had cracked and split at the thrust bearing housing for the input drive shaft. The tail rotor drive shaft exhibited torsional damage consistent with the tail rotor slowing or stopping while the drive shaft continued to rotate while under power. This was consistent with the tail rotor striking the water while under power. The tail rotor balance weights, pitch links and blades did not exhibit damage consistent with having contacted the water under high power.
Photographs taken the morning after the accident showed that the locker door was open but still attached. The door's main structure hinge attachments were still attached to the door and evidence of doorframe fractures was consistent with the locking mechanisms being forced from the closed and locked position. Evidence also indicated that engine and main transmission cowls and tail rotor drive shaft tunnel cover fasteners were secure prior to impact.
Operator's procedures and training
The operator had an air operator's certificate (AOC) issued by the Civil Aviation Safety Authority (CASA) 3 months prior to the accident. The AOC permitted the operator to conduct Search and Rescue but it did not specify permission to drop lifesaving equipment from the helicopter by day or night as required by the Civil Aviation Orders (CAO) 29.5. CASA advised that the operator had not approached the Authority for permission to conduct such operations.
The Civil Aviation Regulation (CAR) 215 required operators' operations manuals to, "contain information, procedures and instructions with respect to flight operations ... to ensure the safe conduct of the flight operations." This operator's operations manual had no information regarding procedures for dropping a life raft by day or night. The manual contained little detail or guidance for night operations, profiles or procedures required for descending the helicopter below minimum descent altitude over water at night, except as provided for in an exemption to CAR 174B provided by CASA. The exemption stated, in part, "The aircraft may only descend below 1,000 ft above the highest terrain within 10 miles after ground definition is established by use of the Nitesun (sic) searchlight using wide beam or the aircraft is established within three miles of destination." The manual did not provide advice, for example, on required crew interaction, the use of stepped descent profiles, maximum rates of descent, or minimum heights at which the helicopter could be flown over water at night.
The manual provided procedures for long over water flights. Flights over water more than 50 NM from a land mass suitable for landing were authorised provided that the flight could be conducted under VFR or night VFR procedures and navigated using two methods as described in the manual.
The operator did not require its pilots to hold a current command instrument rating on helicopters. There was very little information on restrictions or precautions when flying at night in remote areas or over water on dark nights, or considerations of the criteria for deciding whether to conduct operations involving long distances over water at night.
There was only a very brief and general section in the operator's operations manual pertaining to search and rescue operations. There was some additional information in the manual detailing considerations for long over water flights. Such considerations included the statement that "The Bell Long Ranger is not ideally suited to long flights over water. Pilots are to use common sense regarding retrievals from any point more than 50 miles from a place suitable for landing." The operator was not operating a Bell Long Ranger but rather a Bell 407. Although the Bell 206 Long Ranger and 407 share a common heritage, they are different helicopters with significant differences in performance and handling.
The operator did not have a formal risk management procedure to provide guidance to crew to assess risks associated with missions that may have been considered outside normal operations or a decision-making protocol for determining task acceptance or rejection.
None of the operator's personnel had received training regarding life raft deployment techniques, including the patterns to be flown, rigging of equipment, crew interaction, and release parameters. Neither the pilot nor the crewman had previously dispatched a life raft from a helicopter at night and had not received training from the operator in that procedure.
Under certain conditions, external visual reference may be lost while flying an aircraft at night under VFR. These conditions are conducive to spatial disorientation and include operating over remote areas, in moonless or near moonless conditions, over water, and at times when the celestial horizon is obscured by cloud.
Spatial disorientation refers to an individual's failure to sense correctly the position, motion, or attitude of the aircraft or of him/herself. When spatial disorientation occurs, pilots experience great difficulty processing, believing, seeing, or interpreting the information on the flight instruments due to the erroneous information provided by their senses. In addition, the risk of spatial disorientation is high during instrument meteorological conditions (IMC) and night flying in either VMC or IMC.
There has been some research into visual illusions during night helicopter approaches. Previous visual illusion accidents have indicated that it is very difficult for a pilot, in dark-night conditions, to visually assess closing speed, rate of descent and glide path. Moreover, unaided night visual approaches may be as difficult as instrument approaches.
There are substantial difficulties with judging the approach glide path to a small illuminated area at night, particularly over an unlit area such as water. The 'black hole' phenomenon is particularly relevant to approaches over the sea because the intervening area is dark. The 'black hole' effect can provide an illusion of height, therefore, the pilot may perceive that the aircraft is higher than it actually is. In addition, the effect can entice pilots into keeping the visual angle of an approach constant by fixating on a source of light. The approach path will be too steep at first and then flatten out and result in a touchdown short of the nominated point.
Hazy or misty conditions can also influence the judgement of distance. Aerial perspective is affected by the dimming of the image of objects with distance. This, together with the reduction in colour contrast of distant objects, acts as a perceptual clue to distance. Distances therefore tend to be overestimated in low visibility or at night.
These false perceptions are considered to be very powerful. Even when pilots are aware of the 'black hole' effect, they may reject their instrument indications and believe the false impressions of glide path and height that the effect induces. The pilot reported that he was aware of the 'black hole' effect. The pilot also reported that he did not feel disorientated at any stage during the approach or at any other time during the flight.
'Nightsun' searchlight and Radar Altimeter (RADALT) operations
The operator's operations manual outlined some procedures for the use of the 'Nightsun' searchlight. As well as the requirements noted in the CAR 174B exemption provided by CASA, the operations manual also required that when the helicopter was below 500 ft, as indicated on the RADALT, the searchlight be operated on maximum beam width. On approach to land, the searchlight was not to be manipulated in azimuth or elevation below 200 ft RADALT altitude. Azimuth checks of the approach path were to be effected by yawing the aircraft. The RADALT warning was to be set to 200 ft.
The reflection, scattering, or other distortion of the searchlight beam by particles in the atmosphere over water, such as sea salt or sea haze may have produced what is sometimes called the 'fishbowl' effect. The pilot reported that during the passes over the stranded yacht, the searchlight seemed to make conditions a little blurry, like looking through a milk bottle.
Helicopters are rarely manually flown to low levels over water at night and those helicopters that are intentionally operated in such operations are normally equipped with automatic pilot and 'coupled' systems. These systems automatically conduct the approach, hover and departure with the pilot(s) monitoring the profile and system operation.
The pilot commenced the approach from a height of 1,500 ft at about 1,900 m from the yacht and the helicopter impacted the water about 600 m short of the yacht. The inaccuracies induced by attempts to estimate distances at night, and given that the impact point distance from the yacht was also an estimation, it is likely that the pilot commenced his descent somewhat further out than he thought. However, even if the descent point was twice the distance he thought, then the rate of descent at about 50 to 60 kts would have been about 700 ft per minute, which correlates with the pilot's report that the helicopter was descending at 700 ft per minute passing 150 ft. The pilot also reported that he had diverted his attention to the outside, to a totally visual approach using only the searchlight for illumination. He had noted visual perception problems during the passes over the yacht. Although the pilot did not feel disorientated, he may have been experiencing the 'fishbowl' effect and some associated subtle disorientation and distortion of visual cues during the approach.
A descent rate of 700 ft per minute at 150 ft above the water was very high. The pilot was unlikely to arrest the rate of descent at 50 ft without the application of significant power. The wreckage evidence was consistent with the tail rotor striking the surface of the water at low power. Consequently, the introduction of a large amount of power before impact was unlikely.
It could not be determined if the use of the searchlight mitigated or exacerbated the 'black hole' effect. Any effect may have depended upon the intensity, angle, and beam width of the searchlight and what areas the searchlight illuminated during the approach. The pilot decided to revert to a visual only approach using the searchlight. It is likely that some form of visual illusion adversely influenced the pilot's handling of the helicopter during the latter part of the approach toward the yacht.
The high rate of descent flown during the latter stages of the approach was an inappropriate technique applied by the pilot. That was probably a result of the inadequate operator procedures and the pilot's lack of recency and proficiency in over-water night operations. Although the pilot was using the searchlight to assist him make a visual approach, the pilot lost situational awareness and did not visually comprehend the high rate of descent or the amount of power and control movement required to arrest the rate of descent. The pilot's loss of situational awareness was probably due to the lack of visual cues in the dark-night conditions and the lack of ground definition in the beam of the searchlight.
The decision to descend to 50 ft in black night conditions without the assistance of automatic stabilisation, height hold, automatic pilot or coupled systems was questionable especially when there was a lack of regulatory approval for the planned dropping of rescue equipment. The decision to transit the single-engine helicopter over water for an extended distance without a flotation system was arguably risky. The pilot appeared to have an inadequate understanding of the risks associated with the flight as it was planned especially considering the lack of regulatory approval, and his limited equipment, procedures, training and experience. The absence of clear organisational protocols for task acceptance or rejection may have influenced the pilot in accepting a task that involved a high risk.
The lack of formal risk management policies and procedures in determining task acceptance created an environment where the pilot was placed in a position where decisions were made without guidance as to what the operator considered acceptable risks. Although the operations manual permitted the helicopter to be operated below minimum safe altitude at night and to conduct search and rescue operations, the AOC did not permit the dropping of lifesaving equipment. Additionally, the operations manual provided no guidance on how such activities were to be conducted, including the patterns to be flown, rigging of equipment, crew interaction, and release parameters.
The crewman was usually employed as a paramedic and had been with the operator for 2 years as a part-time crewman, but he had not received CRM training. Consequently, the crewman was probably ill equipped to effectively contribute to the overall safety of the operation.
Although the crew successfully escaped the submerged helicopter wreckage, the difficulties experienced by the crew during the escape suggests that initial training and recency in helicopter underwater escape training (HUET) would have probably assisted in reducing the difficulties experienced.
The operator's lack of adequate documentation and associated lack of appropriate training, risk assessment tools, and published guidance inappropriately placed a large responsibility on the pilot to balance the safety of the aircraft and its crew with achieving life-saving missions that were the unit's function.
The helicopter was inadvertently flown into the water. The circumstances indicate that the accident was a result of human performance limitations and an absence of robust organisational defences.
- The pilot was appropriately licensed and medically fit to conduct the flight.
- The crew was not adequately trained to conduct the flight.
- The operator did not have regulatory approval to drop articles from the helicopter by day or night.
- The operator's operations manual did not contain the required information or procedures for the pilot to conduct dropping of equipment from the helicopter.
- The operator's procedures, training and supervision were not adequate for the pilot to accept a night search and rescue operation over water.
- The crew was not adequately prepared for an emergency egress when the helicopter entered the water.
- The helicopter was considered capable of normal flight prior to impact with the water.
- The operator's procedures were not appropriate to accept, plan and conduct an over-water, night, search-and-rescue flight.
- The helicopter was not adequately equipped to conduct a night, over-water, search and rescue flight.
- The conditions at a very low height above the water surface were conducive to visual illusions.
- The helicopter entered a high rate of descent on approach to the stranded yacht.
|Date:||27 April 2001||Investigation status:||Completed|
|Time:||2330 hours EST|
|Location:||Howard Patch, Swain Reefs|
|Release date:||30 April 2003||Occurrence class:||Operational|
|Report status:||Final||Occurrence category:||Accident|
|Highest injury level:||None|
|Aircraft manufacturer||Bell Helicopter Co|
|Type of operation||Aerial Work|
|Damage to aircraft||Substantial|
|Departure point||Rockhampton, QLD|
|Departure time||2145 hours EST|
|Destination||Hixson Cay, QLD|
|Role||Class of licence||Hours on type||Hours total|