International

The pilots of a Bell 212 helicopter (VH-HHW) and an Aerospatiale AS-350B2 Squirrel helicopter (ZK-HNE) were engaged in aerial filming for a motion picture sequence above the middle of Rees Valley in the Southern Alps of New Zealand.

The pilots were very experienced in aerial filming, and conducted a thorough pre-flight briefing for the "point in space filming sequence". The briefing included flightpaths, airspeed, altitude, emergency actions, abort procedures, clearance distance and weather minima. The location features provided few peripheral visual cues for hovering and judging the rate of closure and distance between the helicopters.

The Squirrel was in a hover facing North-West or upstream towards the mountains at 2,500 ft above ground level (AGL) filming the Bell in a fly-by manoeuvre. The filming sequence required the Bell to descend from 3,500 ft AGL at 70 knots towards the Squirrel passing by the right side of the Squirrel (North-West to South-East) and then continue flying straight ahead. The Australian company Operations Manual (Section D4.1-Still and Motion Photography) required the pilot of the Bell to maintain "normal separation" with another aircraft involved in an aerial filming sequence. This separation was defined by the Chief Pilot as 150 m.

During this manoeuvre, the second run for the day, the main rotor blade of the Bell struck the top of the vertical fin of the Squirrel. The pilot of the Squirrel reported some moderate wake turbulence from the rotor tip vortices of the Bell during this pass but neither pilot realised the helicopters had collided. Consequently, the minor damage was not discovered until the helicopters returned to Queenstown at the end of the day's filming.

Inspection found that the top of the Squirrel's vertical fin had been struck by the Bell's main rotor blade. There were two small dimple indents on the leading edge of the main rotor blade cap and some paint scratching in from the end of one main rotor blade. The first dimple was 146 mm from the blade tip and the second dimple was 57 mm from the blade tip.

The investigation revealed that the "point in space filming sequence" manoeuvre can induce a "rejoin illusion" in pilots that limits their ability to accurately judge closure rates. In particular, the pilot of the Bell may have initially experienced an apparently very slow closure rate on the Squirrel followed by a rapid, difficult to judge, increase in apparent closure rate from approximately 100 m to run. The closure rate of the Bell was approximately 120 ft per second. The rejoin illusion is more marked with higher closure rates and the smaller the aircraft being approached. In addition, the black paint scheme of the Squirrel against the relatively dark background of the terrain may have made it even more difficult for the pilot of the Bell to judge the position of the other helicopter. This poor visual contrast had been discussed in the pre-flight briefing.

In addition, the investigation found that the workload of the Squirrel pilot was very high which may have precluded his ability to detect the impending collision and to call an abort. The Squirrel pilot was the aerial director of the film sequence and was subject to additional airborne communications and the professional pressure required to produce quality direction as well as maintain the helicopter in a 2,500 ft AGL hover in strong winds with limited visual cues. Furthermore, it is possible that the Squirrel pilot may have drifted laterally towards the Bell 212 because it is very difficult to maintain an exact stationary hover at altitude with limited visual references.

The absence of a clear and specific quantitative definition for "normal separation" in the Operations Manual for the Bell 212 (Section D4.1- Still and Motion Photography) represented a latent failure in the operator's procedures. Following this incident, the Operations Manual was amended to clarify the definition of "normal separation". In addition, company pilots involved in New Zealand operations were issued with an Operational Memo that imposed a specific quantitative interpretation of "normal separation".

The operator of the Squirrel amended their procedures to stipulate that camera helicopters in high hovers without nearby visual references were required to maintain a minimum indicated airspeed of 10-15 knots to reduce the possibility of subtle lateral drift. In addition, the operator documented specific lateral clearance limitations between helicopters engaged in aerial filming sequences.

Organisational and regulatory issues that became apparent during the investigation included separation distances between aircraft in close proximity and the definition of formation flying. The Australian Civil Aviation Regulation 163 AA states that aircraft must not be flown in formation unless each of the pilots in command has been approved by the Civil Aviation Safety Authority (CASA) to fly in formation and the formation is pre-arranged between the pilots in command. For the purposes of the regulation, two or more aircraft are considered to be in formation if they are flown in close proximity to each other and they operate as a single aircraft with regard to navigation, position reporting and control. In addition, aircraft are considered to be in formation during join-up and breakaway (CAR 163 AA 5(b)). New Zealand CAR 91.227 has similar provisions.

The New Zealand Civil Aviation Authority (CAA) legislation was the relevant legislation in force at the time of this incident and CAR 91.227 stated that no pilot shall operate an aircraft so close to another aircraft as to create a collision hazard. Formation flight is defined as more than one aircraft which navigate and report as a single aircraft; and are no more than one nautical mile laterally and within 100 ft vertically from the formation leader. The aircraft were flown so close to each other as to create a collision hazard. Close formation flying training and certification may have assisted the pilots to avoid a collision on this occasion. Both CAA and CASA are currently reviewing and developing the safety requirements, advisory material, and acceptable standards for operations where aircraft are flown in close proximity to each other in a commercial operation, such as aerial film making.

The organisational and regulatory issues have been addressed in greater detail in the Civil Aviation Authority of New Zealand Aircraft Accident Report 99/2768.

The pilot in command reported that during cruise on a flight from Singapore to London, he began to suffer the increasing effects of food poisoning. Four technical crew members are carried on the Singapore London sector, and when he became ill, the pilot in command transferred control of the flight to a co-pilot. After consultation with a crew member who was a qualified nurse, the pilot in command commenced a period of bed rest. About three hours later, his condition improved, and he resumed formal control of the aircraft. The pilot in command believed that the source of his illness was food consumed during the stopover in Singapore and was not the result of a crew sandwich snack, the only food he had eaten in-flight prior to falling ill.

As the aircraft approached the top of climb the crew received a warning indicating a failure of the equipment cooling system. Ground engineering were contacted and the failure was confirmed. After dumping fuel, the aircraft returned to London and landed without further incident. A post-flight inspection revealed broken wiring within the electrical loom to the equipment cooling valve. The wires had arced and there was evidence of charring to the cargo hold insulation blanket in that area.

Because the aircraft had returned to London, the incident was investigated by the UK Air Accidents Investigation Branch. They reported that the broken wiring was difficult to locate as it had been incorrectly routed beneath the thermal insulation blanket in the forward cargo hold. It was evident that a small fire had occurred to the outer film of the blanket and that this was associated with the broken wiring. The fire had affected an area of about 40 X 15 cm. Water, resulting from condensation, was present in the bilge and it was considered possible that this may have limited the extent of the fire. As the integrity of the blanket had not been compromised, it was not replaced. The blanket had recently been changed for a lighter weight blanket manufactured in-house by the operator and met the flammability requirements. The wiring was repaired by in-line splicing and the aircraft returned to service.

The report added that the maintenance crew considered that the wires may have been inadvertently damaged when they were stepped on whilst hidden from view, possibly when the blanket was replaced. The maintenance personnel reported that it was not uncommon to lose balance whilst working within the cargo bays.

During climb, the crew noticed an odour in the cabin which was suspected to have resulted from bleed air system cleaning during earlier maintenance. Further checks carried out by the crew identified a strong smell of petrol, increasing in intensity towards the rear of the cabin. As the aircraft was carrying dangerous goods, detailed as a petrol engine in the forward hold, an immediate return to Los Angeles was initiated. During the return the smoke/fumes removal drill was carried out and fuel was jettisoned. The cabin crew were instructed to switch off any non-essential electrical equipment and the aircraft was descended to 20,000 ft. Oxygen masks were not deployed and the return to Los Angeles was completed without further incident.

A subsequent ground inspection of the forward hold revealed that a motorcycle had fallen onto its side and petrol had leaked from its fuel tank. The petrol spill had been contained within the hold. The motorcycle was offloaded, the petrol spill was cleaned up and the service continued. The operator carried out an investigation into the incident and determined that the motorcycle fuel tank had been drained to the reserve level for shipment. This complied with the dangerous goods regulations for transportation of the motorcycle in an upright position. However, the motorcycle had been inadequately restrained on its transport stand. Only two securing straps had been used instead of five, and no timber had been used between the motorcycle and the pallet floor. This had resulted in the motorcycle falling over, probably during take-off, and the remaining fuel leaking out.

Safety action

The operator, in conjunction with the overseas freight handling agent, instigated an immediate retraining program for all staff involved in export handling procedures. In addition, new instructions have been issued for the handling of dangerous goods.

Prior to the aircraft departing Lord Howe Island, the Terminal Area Forecast (TAF) for Norfolk Island did not require the pilot in command to arrive with fuel for holding or for diversion to an alternate airfield. During the course of the flight, the weather at Norfolk Island deteriorated. The TAF was initially amended to require 30 minutes holding and later amended to require 60 minutes of holding fuel. The pilot advised that he became aware of the deteriorating weather at his destination only after he had passed the point of no return (PNR).

When the aircraft arrived in the Norfolk Island circuit area, the pilot assessed the conditions as unsuitable to land and commenced holding at low level over the water, but within visual range of the island. Approximately 45 minutes later, the weather conditions improved sufficiently for the pilot to make a visual approach and landing. The aircraft landed with required fuel reserves. Investigation of this incident did not reveal any deficiencies in the conduct of this flight. The airline has advised that as a result of this incident, they have changed their fuel policy to require the carriage of additional fuel where possible.

The take-off was rejected at speed of approximately 30 kts due to EICAS message 'L ENG BLEED'. The operator advised that the right pack flow control shut-off valve was replaced due to suspected faulty electrical connector. Subsequent leak and BITE checks confirmed normal operation.

FACTUAL INFORMATION

The Boeing 747 (B747) was maintaining flight level 350 (FL350) when the crew received a traffic alert and collision avoidance system (TCAS) resolution advisory, warning of conflicting traffic crossing their track at an altitude 400 ft below. They were able to contact the other aircraft, which was a Douglas DC8 maintaining FL330 in accordance with air traffic control (ATC) instructions.

Both crews were able to maintain their respective levels and no evasive action was required. When the DC8 departed Auckland, ATC verified that the secondary surveillance radar altitude readout had correlated with the reported altitude from the crew. However, on arrival at Honolulu, ATC noted a 1,500 ft difference in the altitude reported by the crew to that showing on the radar display. The aircraft transponder was providing an erroneous altitude, but the crew had no flightdeck display to enable them to check what information the transponder was emitting.

The equipment failure had occurred between departing radar coverage at Auckland and the point at which the B747 crew received the TCAS alert. Initial maintenance action by the company indicated a faulty encoder, but an ongoing investigation in the USA revealed that the central air data computer had been providing faulty inputs to both transponders.

SAFETY ACTION

As a result of this occurrence, the Bureau of Air Safety Investigation is investigating a perceived deficiency involving the lack of information available to flight crews regarding the serviceability of altitude encoders. In addition, the Bureau is investigating the lack of information displayed to crews regarding altitude information being transmitted by transponders. Any recommendations issued as a result of these investigations will be published in the Bureau's Quarterly Safety Deficiency report.

A Boeing 747 (B747), en route from Sydney to Hong Kong, was maintaining flight level 350 (FL350) and had been radar identified by Manila Air Traffic Control. The flight crew observed another aircraft maintaining the same level approximately 20 NM to the east displayed on their aircraft's traffic alert and collision avoidance system (TCAS). The B747 crew sighted the other aircraft as it crossed their track from east to west. The crossing aircraft was en route from Manila to Kuala Lumpur and had initially been assigned FL280.

On first contact with radar control that crew had been instructed to climb to FL350. The controller noted the proximity of the two aircraft and instructed the crew of the B747 to climb immediately to FL370. At the same time the B747 TCAS announced a "Climb" resolution advisory (RA) instruction. The B747 crew complied with the climb instruction. The crew of the crossing aircraft advised the B747 crew that they had received a TCAS RA instruction to descend which they had followed. There was a breakdown of separation. Following an investigation of the occurrence the Republic of the Philippines, Department of Transport and Communications air traffic services investigator reported that all area control centre controllers would undergo radar simulator training to enhance their proficiency. The training was to commence in January 1998.

Port Moresby ATC passed coordination to Brisbane Centre on ANA923 and QFA 114 but the flight levels coordinated were incorrect. ANA 923 was coordinated at flight level 390 and QFA114 at flight level 370. At 1700, the pilot of ANA923 reported at VIPAM at flight level 370. When this was passed to Brisbane sector 11, confirmation of the flight level was requested, and this was confirmed by the pilot. Sector 11 contacted Port Moresby by telephone, and Port Moresby confirmed flight level 390.

At approximately 1710, Port Moresby called back to apologise and advise that the level coordinated should have been flight level 370, and QFA 114 should have been flight level 390.

FACTUAL INFORMATION

The Airbus A340 (A340) was on air route A587 and the Boeing 737 (B737) was on air route G462. The routes intersected at waypoint KETUT, which is 200 NM bearing 103 degrees magnetic from Bali. Both aircraft had been cleared to enter the Bali flight information region (FIR) at flight level (FL) 350. The waypoint KETUT is a reporting point for aircraft on A587 but not for aircraft on G462. All communications prior to this point were made on high frequency (HF) radio SELCAL, which does not alert pilots that there may be conflicting traffic.

The conflicting traffic was under the jurisdiction of the Bali East controller. There was radar coverage to approximately 150 NM, and a combination of procedural and radar control was being used by the controller. Flight plans for both aircraft had been received at the Bali Control Centre. However, the flight plans did not indicate an estimate for the KETUT position.

At the time of the incident, the controller had three aircraft on his frequency - the B737, the A340, and a Boeing 747 (B747) en route Singapore to Sydney. The B747 was tracking via Bali at FL330 and the B737 would have had to descend through that level for arrival at Bali. The B747 was identified on radar and was estimating overhead at Bali at 1436 UTC. The other two aircraft were not identified on radar.

At 1410, the A340 pilot reported to Bali East at ONOXA, a reporting point on the FIR southern boundary. ONOXA is 197 NM from KETUT on the designated route A587. The Bali East controller then requested an estimated time of arrival (ETA) for IKAPI, a reporting point on the northern FIR boundary where the aircraft would exit the FIR. The pilot advised an estimate of 1530 and the controller coordinated this information to Ujung Pandang, which was the next control agency.

KETUT was a compulsory reporting point for aircraft on A587. The reason the A340 crew did not advise an estimate for KETUT when reporting at ONOXA was not established. The reason the controller did not request A340's ONOXA estimate was also not established.

At 1428, the crew of the B737 reported at SOTRA at FL350. The Bali East controller requested an ETA for GABIT, a reporting point 150 NM east of Bali, and the crew advised that their ETA was 1447. At 1439 the crew of the A340 requested advice of any traffic at FL350. The controller asked the crew to repeat the request. The A340 crew then stated that they were descending to FL310 to avoid conflicting traffic. The crew of the B737 asked the crew of the A340 to report their position. There was no reply to this request. The A340 crew then reported to the Bali East controller that there was traffic 2 NM to their north, passing from right to left at FL350. The controller questioned this report. The A340 crew repeated the information and reported that they were maintaining FL310. The controller then advised the A340 to "maintain FL310 for a while". At 1443, the A340 was cleared to climb to FL350 by the Bali East controller.

At the time of the occurrence, the control centre was staffed by four controllers and a supervisor. The Bali East controller had left the control room on a break and another controller had taken over control duties of the Bali East sector. The controller taking over had not been aware of the potential conflict between the aircraft on air routes A587 and G462.

Although the occurrence location was within normal radar coverage, the radar data was not being recorded during the period of the incident due to a technical problem.

Each control position had a single flight progress strip bay. The bay was used to store pending flight progress strips. Active flight progress strips were placed on the flat console surface in front of the radar screen. There was a checklist for the compilation of flight progress strips, but this had not been compiled with.

ANALYSIS

The controller had taken over the Bali East sector duties only a short time before the incident and he had not been properly briefed on the traffic that was within his jurisdiction. His attention appeared to have been focussed on the potential conflict between the southbound B747 at FL330, and the B737 inbound to Bali at FL350. He was aware that the B737 would require descent through the B747's level but had not been briefed that there was a requirement to establish vertical separation between the A340 and the B737. The situation was compounded because the flight progress strips were not prepared in accordance with the checklist and the flight progress bays were not being utilised in the most appropriate manner to provide situational awareness of the traffic in the sector.

Although, in this instance, an estimate for the KETUT position was omitted by the crew of one aircraft, the provision of an estimate by the crew of the other aircraft may have assisted the controller to better appreciate the traffic disposition, and alerted him to the confliction. In this context, the promulgation of KETUT as a compulsory reporting point for the two intersecting routes (A587 and G462) would have provided a higher level of safety.

Controllers normally combined flight progress strips for aircraft being controlled on the radar display console. However, this action ensured that aircraft being controlled by different procedures (radar and procedural control) were not easily differentiated. It also provide limited cues to controllers to assist them in maintaining an awareness of traffic disposition in their area of responsibility. Use of the available flight progress board with a number of key position designators would assist controllers in the management of aircraft under procedural control. Positioning the flight progress strips for radar-identified aircraft at the radar display console, adjacent to the procedural flight progress board, would have provided a better overall representation of traffic disposition.

SIGNIFICANT FACTORS

1. KETUT was not a compulsory reporting point for both routes.

2. The controller who compiled the flight progress strip for the A340 did not notate KETUT on that aircraft's strip.

3. The controller handing over responsibility for Bali East control did not conduct an adequate handover.

4. The Bali East controller did not adequately review the active flight progress strips after taking over responsibility for the position.

5. A procedural flight progress board was not used to manage aircraft operating in the Bali East area of responsibility.

6. The crew of the A340 did not advise an estimate for KETUT, a compulsory reporting point.

7. The Bali East controller did not appreciate the conflict between the A340 and the B737.

SAFETY ACTION

As a result of this occurrence the B737 operator:

1. issued a safety notice to all aircrew advising them of the details of the occurrence; and

2. recommended that the priority be given for the fitment of a traffic alert and collision avoidance system (TCAS) to company aircraft operating international flights.

In addition, the Bureau of Air Safety Investigation suggests that the Indonesian Directorate of Aviation Safety, in conjunction with Angkasa Pura I:

1. review flight progress strip display practices and procedures, including strategies to ensure their correct compilation;

2. review published handover/takeover procedures, including strategies to improve controller compliance; and

3. 3. Include KETUT as a compulsory reporting point for aircraft operating on route G462.