The pilot reported that during two attempts to land on Runway 08 he experienced handling difficulties with the aircraft. He eventually landed on Runway 05. An inspection subsequently revealed the propeller had suffered a ground strike and the left main landing gear door was open.

A gusting crosswind of 15 to 25 knots was reported at the time of the occurrence.

Investigation determined that the locking balls were missing from the left main gear door actuator which would allow the door to open if hydraulic pressure was lost. An intermittent open circuit was also detected in the gear extend circuit. This defect caused the hydraulic pump to stop intermittently and may have resulted in the left door opening in flight.

Had the left main gear door opened during the landing sequence it may have contributed to the handling difficulties experienced by the pilot in the gusting crosswind conditions.

The pilot had planned to ferry the aircraft to Rockhampton in accordance with the Visual Flight Rules. He had also arranged to return to Sydney the same day by airline, so as to be able to spend Christmas at home. In order to connect with the return flight, the ferry flight needed to depart before dawn. A weather forecast obtained by the pilot the night before the flight indicated conditions would be unsuitable for visual flight to Coffs Harbour.

The pilot said that when he arrived at Bankstown Airport early the next morning, he assessed the weather as being slightly better than forecast. Consequently, he departed at about 0350, without lodging flight details, and proceeded to fly north up the lane of entry. Passing Patonga the weather started to deteriorate. Light drizzle associated with a decreasing cloud base caused him to consider whether to continue or return. He then noticed that the directional gyro began to malfunction and would not stay aligned with the magnetic compass. Whilst trying to rectify that problem he also noticed that the ADF indications appeared to be unreliable. With his attention diverted by the instrument problems, the pilot lost visual contact with the coastline and decided to return to Bankstown using the magnetic compass as a heading reference. Whilst in a timed turn to the left the aircraft collided with trees and was destroyed.

After regaining consciousness, the pilot managed to extricate himself from the wreckage and walk three kilometres to a farmhouse, over hilly, heavily timbered terrain.

The helicopter was being used for a controlled firebombing and burning off operation. The pilot had been flying very slowly just above the treetops, then after turning onto a southerly heading he believed the engine lost power and was unable to prevent it from striking the tops of the trees. It then descended steeply into the ground, the pilot receiving severe back injuries, and the passenger a broken arm.

An investigation of the helicopter and engine failed to find any fault, or malfunction, that may have caused the engine to lose power.

Weather conditions were very hot with a light northerly wind blowing.

The helicopters weight was calculated to be in excess of its maximum all up weight, with heavy items of equipment stored in the areas below the seats, contrary to the flight manual and placarded instructions.

Being overweight for the operation, and turning downwind, i.e. to the south, the helicopter probably suffered a loss of translational lift with subsequent overpitching of the rotor system by the pilot, giving the impression that the engine had lost power. With no available height margin the pilot was unable to avoid flying into the trees.

On departure the pilot of VH-DXI requested climb to amended altitude 10,000. Due to another aircraft just ahead at 8000 feet the controller issued a clearance to climb to amended altitude 7000 feet. On climb the pilot's attention was diverted when a passenger spoke to him. The aircraft had climbed to almost 8000 feet when the controller queried the pilot on his altitude. The pilot apologised and descended back to 7000 feet. The longitudinal separation at the time was four miles, instead of the required five miles.

Significant Factor

The following factor was considered relevant to the development of the incident:

1. The pilot inadvertently climbed the aircraft above the altitude he was cleared to.

FACTUAL INFORMATION

History of the flight

Both aircraft were operating scheduled passenger services and were en route from Brisbane to Cairns. JA8104 operating as JAL776, departed Brisbane at 2355 UTC on climb to FL290. VH-CZN departed two minutes later on climb to FL 310.

At 0003, a departure message incorporating the secondary surveillance radar (SSR) code allocation message (CAM) was received by the Cairns aircraft data systems officer (ADSO). The message contained four blocks, each of four numerals representing the departure times and assigned SSR codes for JAL776 and VH-CZN. In preparing the flight strips for the two aircraft, the ADSO inadvertently transposed the codes and departure times, resulting in VH-CZN being planned into the Cairns radar data system against the JAL776 code and departure time, and vice versa.

At 0055, abeam Townsville estimates of 0017 for JAL776 and 0020 for VH-CZN were passed to Cairns Arrivals. At 0118 both aircraft were handed off from Brisbane Control to Cairns Arrivals. The aircraft were handed off using the phraseology "south by two that is JAL776 and Charlie Zulu November". The handoff was accepted by the Cairns Arrivals controller even though the labels showed VH-CZN to be ahead of JAL776.

Subsequent events and relevant times were:

At this point, the Approach controller realised that the radar labels for JAL776 and VH-CZN were transposed. Both aircraft were then processed normally and landed without further incident.

Investigation of the occurrence revealed the following:

The ADSO had been suffering from a headache for two days prior to the incident. It was still present on the day of the incident, but the ADSO felt obliged to attend work as, two days earlier, she had taken the day off because of the headache.

In the ATS system in use at the time, aircraft SSR codes were entered manually by ADSOs on receipt of code allocation messages from adjoining ATS centres. There was no cross reference of aircraft levels and codes, either by the ADSO, or by any air traffic controller.

Although code allocation messages usually referred to only one aircraft, it was not unusual for two aircraft to be included in one message. In this instance, the four-figure SSR codes as well as the departure times for both aircraft all began with the numerals 23, thus increasing the potential for error when the information was transferred.

For a few months preceding the occurrence, there had been problems concerning the SSR mode-C display on Cairns radar. While these had involved correlation of departing aircraft, there were indications of a level of suspicion among the controllers regarding the reliability of the SSR mode-C display.

During the radar handoff of the aircraft from Brisbane to Cairns Arrivals, there was no bearing and distance given for the aircraft, either with respect to a common position (such as Townsville) or to each other. This resulted in an opportunity for rectifying the misidentification of the codes to being missed.

Paras 6-9 of the Manual of Air Traffic Services (MATS) 9-5-2 address radar handoff. However, they refer to single aircraft handoffs only and do not address multiple aircraft handoffs.

Although the abeam Townsville estimates indicated that JAL776 was ahead of VH-CZN, there were indications that these estimates could be unreliable. It was reported that the day before the incident, two aircraft were handed off by Brisbane with the second aircraft having the earlier estimate. This may have encouraged a climate whereby estimates were considered unreliable indicators of aircraft position.

CONCLUSIONS

Significant factors

The following factors were considered relevant to the development of the incident.

1. The physiological condition of the ADSO may have reduced that person’s task efficiency.
2. The code allocation message referred to two aircraft.
3. The ADSO transposed the SSR code information for both aircraft.
4. A check was not conducted to confirm that the correct SSR codes had been entered against each aircraft.
5. The radar handoff was such that positive aircraft identification was not assured.
6. MATS procedures did not cover multiple aircraft handoffs.
7. Previous problems with SSR mode-C readouts may have influenced the controllers to assume that the altitude labels for the aircraft were incorrect.

SAFETY ACTION

As a result of the investigation, the Bureau of Air Safety Investigation issued the following interim recommendation

to the Civil Aviation Authority on 13 December 1994.  The response to the interim recommendation from Airservices Australia is also reproduced in part.

IR940300

The Bureau of Air Safety Investigation recommends that the Civil Aviation Authority:

1. review message format procedures to ensure that separate messages are used for departure and SSR code allocation information for each aircraft;
2. review the radar hand-off methods to ensure that individual aircraft validation needs for each unit are appropriate to the equipment and procedures in use at that unit; and
3. introduce a system of SSR code integrity checks between ATS centres and, where appropriate, between individual sectors within the same centre.

Airservices Australia response

Head Office and District Office (ATS) meetings were held to discuss the issues and implications of the Bureau's recommendations, and the following changes to procedures have been implemented.

Message format has been amended so that double spacing appears between all aircraft departure and code allocation advice.  The error rate has been greatly reduced and the problem of "dyslexic" interpolation of callsigns is no longer apparent.

Hand off methods between units have been addressed by the issuance of an interim MATS amendment (IMA) 13A effective 18 August 1995.  This new procedure was installed by local direction pending the effective publication date.

MATS 9-5-2 Para 4.b

Add new second sentence so that sub-para reads as follows:

b. .... by specifying the location of the radar return by a bearing and distance from a known point or fix, together with the observed track or return. When aircraft are within 10 NM, or a distance as otherwise specified in Local Instructions, of one or more other aircraft, relative position information will also be passed to ensure correct relay of identification. The receiving controller may consider identification positive if only one return observed on the display agrees with the information specified..."

MATS 9-5-2 Para 4.f

After existing sub-sub-para f. (3) add new NOTE as follows:

"NOTE: This technique shall not be applied across boundaries of non-linked RDP systems."

Procedures have been introduced into the NDO to provide timely advice of code allocation and insertion into the RDP system, reducing the chances of errors being generated by this work being done at the ATC console.

Hand-off procedures are now considered secure to pick up code-based errors.

Response classification:  CLOSED-ACCEPTED

The design of Area Alpha was negotiated between the gliding clubs and ATC. It was intended to provide suitable airspace to cater for the traffic density, and to meet the needs of the training syllabus for glider pilots. For example, the average 1,500 ft between ground level and the base of the 2,000 ft step is insufficient for spin recovery training which is mandatory for all glider pilots.

The gliding clubs have a record book adjacent to the telephone in the club house to record details of the release of the airspace and have an 'Alpha Open' sign at the launch point to advise pilots when release approval has been obtained from ATC.

During the launch of the three gliders the 'Alpha Open' launch point sign was displayed although no request for release had been made to ATC, and no approval had been given. The glider pilots were not aware that Area Alpha had not been released. ATC routed the B767 through the area in the belief that glider traffic was conforming to the area step restrictions. Weather conditions at the time were such that the gliders were able to climb to 4,000ft.

There was no indication in the record book adjacent to the club house telephone that any contact had been made with ATC, and ATC did not have any record of telephone calls received from the clubs.

The gliding clubs were not able to determine who had displayed the sign that day and were not sure that the sign had been removed after the previous day’s flying.

The B767 had been correctly routed through the area. The crew was alert to the high-density traffic and was maintaining a heightened visual scan during the descent into Avalon.

Significant factors

The following factors were considered relevant to the development of the incident:

1. The 'Area Open' sign was displayed when an ATC clearance was not available.
2. ATC was not aware that the gliders were operating in controlled airspace.

SAFETY ACTION

During the investigation, Airservices Australia revealed that as part of the implementation of the ICAO Airspace structure on 20 June 1996, the upper limit of the airspace available for gliding OCTA ('G' airspace) will be 3,500 ft over Bacchus Marsh and 4,500 ft to the west of Bacchus Marsh.

The following safety actions have also been taken.

The gliding clubs have:

1. alerted all glider pilots operating at Bacchus Marsh to the circumstances of this incident;
2. tightened up the mandatory recording of telephone requests for the release of Area Alpha airspace;
3. manufactured a sandwich board indicator of 'Area Open' that shows the date, the name of the person who obtained the clearance and any conditions attached to the clearance;
4. required that the sandwich board be placed in the club house adjacent to the telephone at the completion of each days flying; and
5. required that during the first launch after the sandwich board is placed at the launch point the tug pilot is to call ATC to confirm that Area Alpha is open.

The pilot reported that the engine lost power at a height of about 500 ft, shortly after take-off. As he was unable to return to the runway he carried out a forced landing in an open area. During the landing roll the nosewheel entered a ditch and the aircraft overturned. The pilot was able to exit the aircraft without injury.

No defects were found which were likely to have contributed to the loss of power. The engine ran normally during subsequent ground testing.

The crew of PAL210 transferred from Melbourne Control (Sector 6) to Brisbane Control (Sector 5) at 1523 hours. On first contact with Brisbane Control, they advised an estimate of 1527 hours for Cunnamulla. The Brisbane controller had not received co-ordination from Melbourne Sector 6 on the prior position of the aircraft. He only held an estimate based on the departure time and the flight plan time intervals. That estimate was 1534 hours.

Investigation revealed a breakdown had occurred at Melbourne Sector 6, the control position responsible for the co-ordination. This had happened at the time of hand over of responsibilities at the end of a shift. The controller going off duty indicated to the controller coming on duty the need for co-ordination in respect of PAL210 but the manner in which he did this was misinterpreted by the on-coming controller and the required co-ordination was not done.

Significant Factor

The following factor was considered relevant to the development of the incident:

1. A misunderstanding occurred between the controller going off duty and the controller coming on duty.

The pilot had been undergoing dual instruction and had been practicing autorotational landings onto a dry mud flat.

One exercise was for the instructor to hold the anti-torque pedals firmly in the neutral position simulating jammed pedals, the pilot terminating the exercise with a run on landing. He made an approach to a larger, and clearer area of the mud flats, but his initial pass was too slow, and he was unable to maintain directional control. The instructor took over and completed the exercise as a demonstration, touching down in a straight and level attitude, with a ground speed of approximately 10 kt.

Immediately after ground contact the landing skids broke through the firm top layer of the mud crust, causing the helicopter to pitch forward allowing the main rotor blades to contact the ground. The helicopter then cartwheeled and came to rest on its left side, facing back along the approach path.

Approval was given to Melbourne Sector 12 by Sydney ATC for the Nomad to climb clear of the Sydney 230 radial for parachute dropping from FL125. At about the same time, an Airbus was inbound to Sydney from Melbourne via a Rivet STAR. As the Airbus was passing FL130 on descent, the Nomad was observed on radar by Sydney Arrivals, near the inbound track climbing through FL110, in potential conflict with the descending Airbus.

The Arrivals Controller contacted Melbourne Sector 12 who confirmed that they would be separating the two aircraft. Although this was accepted, a short time later the aircraft were observed to pass within 4 NM of each other at the same level, when the minimum lateral separation required was 5 NM.

A subsequent investigation did not reveal any reason for the lack of positive control by Melbourne Sector 12. The incident was also the subject of a separate ATS Quality Assurance investigation.