The helicopter company's operations, based at Cairns Airport, Queensland, included passenger charter flights between The Pier, at Cairns Harbour (4 km SE Cairns Airport) and Green Island (22 km NE Cairns Airport).
At about 1035 eastern standard time the pilot departed The Pier for Green Island in a Bell 206 helicopter with six passengers on board. Because of the likelihood of mechanical turbulence in the lee of the high terrain south of Trinity Inlet, he initially tracked via the Cairns Harbour shipping channel. When he reached the end of the shipping channel, he was unable to see the island because of rain so he descended from his cruise altitude of 500 ft to about 300 ft and was then able to see the island about 9 km ahead. The helicopter arrived at Green Island at about 1045.
At 1130, the pilot departed Green Island for The Pier with six passengers on board. There was light drizzle falling at the time but he assessed that conditions in the area were suitable for flight utilising external visual reference. The pilot again elected to track via the shipping channel. Clearance to enter the Cairns Control Zone was not immediately available because of other traffic, so the pilot conducted a number of orbits in the helicopter until he was issued with a clearance at about 1139 to track to The Pier via the shipping channel, not above 500 ft. The controllers advised the pilot that, within 7-9 km from The Pier, the cloud base was 800-1,000 ft, with some showers, and visibility less than 10 km.
As the pilot continued tracking along the shipping channel, using the channel beacons as track markers, he noticed that the weather conditions ahead were deteriorating. A short time later, he descended the helicopter to about 150 ft to keep the water surface in sight, and reduced speed. At about 1143, the controller cautioned the pilot that a para-sail was operating in the Cairns Harbour area. A short time later, the pilot received a request for his arrival time from the company's office at The Pier. He responded that he expected to arrive in 5 minutes.
The pilot later reported that by that time the weather conditions had deteriorated further, he was flying at 50 ft or less above the water in light to moderate rain and could no longer see any channel beacons. He selected the windscreen demister on as condensation had begun to form on the inside surface. He also armed the inflatable floats that were fitted to the skid-type landing gear.
At about 1146, the pilot asked the controller for directions to The Pier. The tower controller advised that The Pier was on a bearing of 205 degrees M, at a range of 1.5 NM (3 km). At about that time, in-flight visibility rapidly deteriorated to an extent where external visual cues were not available. The pilot, noticing that the altimeter was indicating 100 feet, placed the helicopter in a gentle descent in an attempt to keep the surface of the water in sight. The helicopter contacted the water a short time later and rolled inverted. The pilot and five passengers quickly escaped from the fuselage to the surface of the water. One passenger was trapped in the cabin for a number of minutes and did not survive the accident.
The helicopter was certified for flight under the Visual Flight Rules and was equipped with a satellite navigation system receiver. Inflatable floats were attached to the skid type landing gear. These could be inflated by the pilot in the event of a water landing. The helicopter was not fitted with a radio altimeter.
The Cairns area was under the influence of south-easterly stream weather. The Bureau of Meteorology issued an amended aerodrome forecast for Cairns at 0808 for the 24-hour period from 1000. The forecast was for an easterly wind at 15 kt, visibility of 9,000 m, and light rain. Some cloud patches were expected with a base of 800 ft, a broken layer at 1,800 ft, and overcast at 10,000 ft. Periods of up to 1 hour of heavy rain, scattered cloud at 800 ft, and broken cloud at 1,500 ft were expected over the forecast period.
Controllers on duty in the tower indicated that the weather conditions had been fluctuating significantly and rapidly throughout the morning. There were periods when conditions met the criteria for VFR flight. This contrasted with intervals of low cloud and very heavy rain, amongst the worst conditions they had seen at Cairns. Radar images and rainfall rates suggested that visibility in the area of the accident could have been reduced to a few hundred metres or less. Personnel who were at The Pier at the time of the accident described the rainfall as torrential, with visibility as low as one car length.
A weather radar system operated by the Bureau of Meteorology was located at Saddle Mountain, approximately 11 km north-west of Cairns Airport. The weather radar data recorded at 1150 showed an area of moderate rainfall centred over Cairns Harbour, adjacent to Cairns City. It extended about 5.4 km north-south and about 3.6 km east-west.
The weather information the controller passed to the pilot was based on his visual assessment of the weather in Cairns Harbour as he saw it from the control tower. When the controller issued the caution to the pilot regarding the para-sail, the radar indicated altitude of the helicopter was 100 ft.
The Bureau of Meteorology advised that conditions of minimum visibility at Cairns Airport occurred during the period between about 1155 and 1210. The recorded rainfall of 5.8 mm between 1150 and 1210 at Cairns Airport was similar to that which would be encountered in thunderstorms. Although there was an automatic weather station at Green Island it was not equipped to measure rainfall.
Examination of recorded Air Traffic Services radar data provided information on the track, altitude, and ground-speed of the helicopter for a portion of the flight. The data indicated that the helicopter was initially tracking via the Cairns Harbour shipping channel at about 100 kts and an altitude of 200 ft above mean sea level. At about 7 km from The Pier, the speed gradually decreased to 55-60 kts and then to below 40 kts. The last recorded speed was 31 kts. The recorded altitude during the final 2 minutes of the recording was 100 ft, apart from one value of 200 ft. The last recorded position of the helicopter was 2.4 km north east of The Pier at about 1148.
Examination of the wreckage confirmed that the helicopter struck the water in a slight left skid-low, nose-low attitude, and at low forward and vertical speeds. All seats and safety harnesses retained their integrity. There was evidence of flexing of the roof frame on the right forward side of the cabin, immediately behind the pilot's seat resulting from induced stresses following main rotor blade contact with the water.
The post mortem examination report stated that the non-surviving passenger had received a minor head injury that may have had sufficient effect to prevent her from releasing her safety harness. The examination established that the passenger died as a result of drowning. The flexing of the cabin roof occurred above the seating position of the passenger who was trapped in the helicopter. It is possible that the roof flexed sufficiently to cause the head injury to that passenger.
Company ground staff who worked at Green Island conducted a safety briefing (in Japanese) for the passengers. Those staff had completed proficiency testing in emergency procedures applicable to Bell 206 helicopters. The operation of the life jackets, seat belts, and emergency exit procedures was demonstrated. The information was summarised on safety information cards (in English and Japanese) in the helicopter. Each passenger wore a life jacket contained in a belt-mounted bag.
The pilot said that, after the cabin filled with water, he was able to easily egress from the helicopter. When he surfaced, he saw 2 or 3 passengers on the opposite (left) side of the upturned fuselage. He dived and attempted to open the passenger door on the right side of the helicopter but was unable to do so. When he next surfaced, there were 5 passengers on the surface. He made a number of further attempts to open the right side door but could not. Two passengers had made a few dives from the opposite side of the helicopter and they brought the injured passenger to the surface.
The pilot reported that, during an earlier positioning flight to The Pier, the airspeed indicator (ASI) was not functioning normally in that it did not indicate above 40 kts. He thought that the fault was probably due to water in the pitot-static system and expected it to clear during the flight to Green Island. However, the fault remained. After landing at Green Island, the pilot sucked then blew into the pitot head in an attempt to remove any blockage that might be in the system. Because there were no maintenance facilities on the island, there was no means of assessing the serviceability of the instrument before the subsequent flight. The ASI did not function during the accident flight. The pilot said that he relied on the ground speed display on the GPS for speed information during the flight. He did not consider that this had any meaningful affect on his cockpit workload during the flight.
The opinion of other experienced helicopter pilots spoken to during the investigation was that the absence of an ASI would have increased the pilot's workload, particularly in view of the weather conditions. The erroneous indication on the ASI and the need to refer to the GPS display would have disrupted the pilot's normal instrument scan pattern. Further, the GPS displayed ground speed, not "airspeed", so the speed information the pilot was receiving was not appropriate to some flight regimes. Civil Aviation Order Part 20, Section 18 specifies that, for VFR charter operations, a helicopter must be equipped with a serviceable ASI prior to take-off.
The company advised that periods of poor weather usually generated higher demand for helicopter flights because rough seas and/or rain discouraged some tourists from returning to Cairns by boat. The pilot indicated that the company expected the pilots to "give it a go" in the case of bad weather. The company indicated that pilots were expected to "have a good look before turning back" during operations away from the departure area, but that there was no pressure placed on pilots to complete flights in unsuitable weather conditions.
The pilot was programmed to conduct a number of other flights later in the day. However, he stated that the schedule had no bearing on his decision to depart Green Island. The pilot reported that the usual routes from Green Island to Cairns were via the shipping channel, or coastal via False Cape. Wind from the south or south east at about 15 knots or greater caused mechanical turbulence in the lee of the high terrain on the southern side of Trinity Inlet. Under such conditions he usually avoided the False Cape/coastal route because of passenger comfort considerations. The accident flight was one such instance.
The pilot said that when he departed Green Island, the weather conditions easily met the VFR criteria. His technique in conditions of deteriorating visibility was to descend, maintain a visual reference outside the cockpit and to reduce speed. He applied this technique on the accident flight. Although visibility was poor, he continued, in part because of his experience in operating in similar conditions, but also because the advice from the controller indicated that the weather would improve as he neared Cairns. However, the pilot emphasised that he had turned back on a number of previous occasions because of unsuitable weather conditions.
The pilot stated that, even though he held a night VFR rating it was not current. In addition, he disliked instrument flight and had undertaken minimal instrument flying since achieving the rating in 1992. In any event, the helicopter was not certified for IFR flight. Against this background, he did not consider turning at low level to fly back towards better conditions as a safe option.
The pilot reported that the visibility conditions during the return flight from Green Island were the worst that he had experienced. The sea surface became flat and featureless and blended completely with the precipitation. By that time, it was too late to turn around. He reflected that he might have been better placed by tracking coastal because vegetation and other land features would have provided a higher level of visual contrast against the rain/cloud and may have enabled him to safely continue the flight. Alternatively, he would have been able to land the helicopter and await passage of the weather.
The aerodrome controller activated the Cairns Airport Emergency Plan at 1147 after the helicopter disappeared from radar and the pilot did not respond to radio calls. The police, ambulance, Queensland Emergency Service (QES) helicopter, and Cairns Aviation Rescue and Fire Fighting (ARFF) unit responded. The ARFF response involved dispatching a vehicle towing a trailer mounted rescue boat to Marlin Marina boat ramp, near The Pier. The vehicle arrived at the boat ramp at 1204 and the boat reached the crash scene at 1209. By that time, a tourist vessel and a seaplane were in attendance and the QES helicopter was overhead. All persons involved in the accident were placed aboard the tourist vessel and taken to the Marlin Marina boat ramp. The ARFF later commented that had a launching facility been available at the Barron River adjacent to the airport, they would have arrived on the scene much quicker.
The circumstances of the accident indicated that the pilot continued the flight into adverse weather conditions to the point where flight using external visual reference was no longer possible. Because the helicopter was not certified for instrument flight, and the pilot's instrument flying experience was minimal, continuation of the flight in the deteriorating conditions, including turning the helicopter onto a reciprocal track without visual cues, involved risk. The pilot's only viable option at that point was to attempt a water landing. In the event, there was insufficient outside visual reference for him to achieve a skids level, zero speed landing.
The pilot indicated that initially there was a gradual, rather than sudden, decrease in visibility. However, the deterioration from low visibility to white-out conditions occurred very rapidly.
There was no indication that a return to Green Island or tracking via another route formed part of the pilot's strategy for the flight. A number of factors could have contributed to this:
- The pilot's operating culture was conditioned from having "got through" adverse weather on previous occasions.
- Having decided to track via the shipping channel because of turbulence considerations on the coastal route, the pilot effectively "locked out" the coastal route as an alternate course of action.
- The weather information passed by the tower controller probably placed an expectation in the pilot's mind that he could negotiate the weather successfully.
- The pilot may have experienced subtle pressure as result of the "have a good look before turning back" culture.
The recorded radar data indicated that the pilot maintained steady control of altitude and speed through most of the flight. The only significant deviation occurred when the controller noted and advised the pilot of the altitude change from 100 ft to 200 ft and back again. This information does not indicate that the malfunctioning ASI had a significant affect on the pilot's control of the helicopter, or the eventual outcome of the flight.
The elapsed time between activation of the airport emergency plan and the ARFF rescue boat's arrival at the crash scene was 22 minutes. The journey from the airport to the Marlin Marina boat ramp took 17 minutes. While there was no consequence for this accident, the absence of a boat ramp into the Barron River at the airport added significantly to the rescue boat launching time.
- The Cairns area was under the influence of south-easterly stream weather, which included periods of low cloud and very heavy rainfall.
- The pilot continued the flight on the direct track from Green Island to The Pier in conditions of deteriorating visibility.
- The pilot experienced sudden white-out conditions that deprived him of all external visual reference.
Action by the helicopter operator
Within a few weeks of the accident, the helicopter operator informed the Bureau that it had taken the following actions:
"1. Amended Section A.7 of the company operations manual to include the following:
A7.2 DETERMINATION OF METEOROLOGICAL MINIMA
- If weather deteriorates to below published VFR, pilots are to have an alternate route or landing route.
- In Controlled Airspace or Control Zones, pilots are to request special VFR from ATC
- Outside Controlled Airspace, pilots may operate to Special VFR Minima.
- If enroute weather conditions deteriorate to cloud base of 500 feet agl or less, and or visibility of 800 metres or less, the pilot should proceed via the alternate route or to the alternate landing area.
- Advise ATC and base of intentions.
- Engaged a consultant to facilitate the establishment of a comprehensive safety management system within the company."
Discussion with the operator on 9 March 2000 indicated that as a result of legal advice, implementation of the safety management system had been suspended until the accident report and Coronial processes had been completed.
As a result of this occurrence, the Australian Transport Safety Bureau (formerly BASI) made the following recommendation.
The Australian Transport Safety Bureau (formerly BASI) recommends that the Aviation Rescue and Fire Fighting (ARFF) unit and Cairns Port Authority examine the adequacy of the current launch facilities for the ARFF rescue boat against the benefits which might accrue from a launch ramp on or adjacent to the airport.
|Date:||12 March 1999||Investigation status:||Completed|
|Time:||1147 hours EST|
|Location:||5 km SE Cairns, (VOR)|
|State:||Queensland||Occurrence type:||VFR into IMC|
|Release date:||31 March 2000||Occurrence class:||Operational|
|Report status:||Final||Occurrence category:||Accident|
|Highest injury level:||Fatal|
|Aircraft manufacturer||Bell Helicopter Co|
|Type of operation||Charter|
|Damage to aircraft||Substantial|
|Departure point||Green Island, QLD|
|Departure time||1130 hours EST|
|Role||Class of licence||Hours on type||Hours total|