The aircraft was involved in a cotton spraying operation. The pilot reported that on the tenth take-off the aircraft failed to accelerate to normal climb speed, only reaching a height of about 15 ft. He dumped the load but was unable to prevent the aircraft descending into the cotton crop. Although the aircraft was substantially damaged the pilot was uninjured.

The engine subsequently performed normally during a test run. The pilot reported that he remembered strong 'willy willy' activity in the area immediately after the accident. He concluded it was likely that the take-off performance of the aircraft had been adversely affected by a wind gust at liftoff.

FACTUAL INFORMATION

The crew of an instrument flight rules (IFR) Saab 340 operating a flight from Sydney to Canberra had received an airways clearance for a Shelleys 5 standard instrument departure (SID) on climb to 3,000 ft. The SID required the crew to track on a heading of 335 degrees magnetic (M) and to turn on to a heading of 210 degrees M when they reached 600 ft on climb. The Saab taxied for an intersection departure for runway (RWY) 34L from taxiway B10 and stopped at the holding point awaiting departure approval. This taxiway was on the eastern side of the runway and approximately 1450m north of the threshold.

The traffic flow was busy when the aerodrome controller west (ADCW) received departure instructions from the departure south radar controller (DEPS) for a Bell 206 (B206) helicopter. The B206 was to depart from the helicopter area to the east of RWY 34/16 to Bankstown, located approximately 10 NM west of Sydney aerodrome. The planned altitude for the B206 was 1,500 ft. The ADCW cleared the pilot in command (PIC) of the B206 to take-off. The PIC of the B206 was approved to cross RWY 34L behind a landing Boeing 747 (B747). At the same time the ADCW approved two taxiing Boeing 737s (B737) to cross RWY 34L at taxiway J which was parallel to and south of B10. After departure the ADCW instructed the PIC of the B206 to change to the DEPS frequency.

The next aircraft in the landing sequence for RWY 34L was a B737. The ADCW estimated that there was sufficient time for the Saab to depart prior to the B737 reaching the runway. The ADCW requested and was granted departure instructions for the Saab by DEPS. As the approaching B737 passed a position approximately 2 NM from the threshold of RWY 34L the ADCW cleared the crew of the Saab for immediate take-off after confirming that they were ready for an immediate departure.

As the Saab accelerated the B737 was on a close final approach. The ADCW was required to provide a landing clearance to the crew of the B737 or instruct the crew to go around if the runway was obstructed. The ADCW cleared the crew of the B737 to land. As the B737 touched down the Saab was approximately 1,700 m further along the runway and travelling at a slightly lower groundspeed than the B737. At the time the Saab became airborne the distance between the aircraft was approximately 1500 m. The B737 landed while the Saab was on the runway.

As the Saab became airborne DEPS called ADCW to coordinate a change of track and level for the previously departed B206. The ADCW approved the changes. At the suggestion of DEPS the ADCW instructed the crew of the Saab to cancel the SID and to maintain runway heading. This was done to maintain separation between the B206 and the Saab. There had been a lack of provision of separation between the aircraft.

Runway separation standards

The ADCW was required to provide the crew of the B737 with landing or go-round instructions before that aircraft reached a height of 200 ft above the landing threshold. Runway separation standards required that landing aircraft should not be permitted to cross the runway threshold until a preceding departing aircraft (less than 136,000 kg maximum take-off weight) was airborne. Controllers were required to consider the effect of aircraft carrying out a go round and the implications for separation with other aircraft.

Technical crew

The B737 co-pilot was the handling pilot for the landing. The crew could not recall if the Saab was airborne or still on the runway when they landed. The provision of a landing clearance to the crew of an aircraft entitled the PIC to continue with the landing if it was deemed safe to do so, or to conduct a go round if the situation was not considered to be safe.

Separation responsibilities between ADCW and DEPS

The ADCW was responsible for controlling arriving and departing aircraft for RWY 34L and was jointly responsible in conjunction with DEPS for separating aircraft in the airspace to the west of RWY 34L.

The ADCW and DEPS did not establish which controller was to coordinate the separation between the B206 and Saab or the type of separation to be used. Both these aspects needed to be coordinated prior to departure instruction being issued and the crew receiving a take-off clearance.

When the ADCW requested departure instructions for the Saab, DEPS assumed that the aircraft would be cleared for take-off after the B737 landed. Consequently, DEPS did not query the ADCW regarding the separation of the B206 and the Saab.

Runway usage

The ADCW believed that there was an opportunity to utilise the northern portion of RWY 34L for the departure of the Saab while the two B737s crossed the runway. This required the ADCW to confirm with the crew of the Saab that they were ready for an immediate departure, to obtain departure instructions from DEPS and to issue the take-off clearance to the crew of Saab prior to the approaching B737 requiring a landing clearance.

As the ADCW issued the take-off clearance to the crew of the Saab the B737 was approximately 2 NM from the threshold of the runway. Aerodrome controllers generally accepted 2 - 3 NM as the point at which the runway should be vacated by other traffic to ensure that an approaching B737 or similar type aircraft could be assured of a landing.

The Saab accelerated slower than the ADCW expected. The ADCW appreciated that runway separation was unlikely to be maintained between the Saab and the B737. Faced with the decision to either approve the B737 to land or to instruct the crew to conduct a go around the ADCW believed that the better option was to clear the aircraft to land. He believed that this option was the safer alternative under the circumstances.

Air traffic service performance

The ADCW felt a degree of pride in his ability to perform tower control duties. He endeavoured to provide minimum disruptions or delays to aircraft.

ANALYSIS

The ADCW's desire to not unduly delay aircraft probably caused him to attempt to facilitate the departure of the Saab at a time when there was little or no margin to compensate for delays in crew reaction to instructions or differences in individual aircraft performance.

It was unlikely that there was sufficient time for the Saab to depart as the arriving B737 had passed the position on the approach used by aerodrome controllers as a guide to assist them in managing runway usage.

The ADCW was left with limited options to resolve the situation. Subsequently, he issued a landing clearance to the crew of the B737 and allowed the crew of the Saab to continue the take-off.

His desire to provide a service to aircraft may have caused him to act hastily and consequently overlook the need to coordinate the provision of separation between the B206 and the Saab after departure, and to miscalculate the runway separation between the Saab and the B737.

DEPS and the ADCW had a shared responsibility to ensure separation was maintained between departing aircraft. However, DEPS incorrectly assumed that the ADCW would not clear the Saab for take-off before the B737 landed. DEPS should have queried the ADCW as to his plan to maintain separation between the B206 and the Saab when the ADCW requested departure instructions for the Saab. Subsequently, it was only the action of the B206 PIC requesting an amended route and level that prompted DEPS to eventually query ADCW and for the potential conflict to be resolved.

SIGNIFICANT FACTORS

1. The ADCW did not coordinate with DEPS for the maintenance of separation between the B206 and the Saab.

2. The ADCW did not ensure that separation would be maintained between the B206 and the Saab prior to issuing the crew of that aircraft with a take-off clearance.

3. DEPS did not query the ADCW with regard to the position of the B206 when the latter requested departure instruction for the Saab.

4. The ADCW did not allow for a sufficient margin between the arriving B737 and the departing Saab to compensate for differences in aircraft performance.

VH-RJE was tracking inbound on a VFR flight from Rockhampton via Charon Point (CHP), on a bearing of 143 degrees from Mackay. When the aircraft was about 35 NM from Mackay, the Brisbane Sector 7 controller provided information on the flight to the Mackay tower co-ordinator. When the co-ordinator created a flight progress strip for the aircraft the tracking details were incorrectly inserted as being via Shute Harbour, a bearing of 328 degrees from Mackay. This information was available to the aerodrome controller when the aircraft reported at 33 NM from Mackay at 4,500 ft. No other position information was provided by the pilot, nor did the controller request any. A clearance to enter controlled airspace and to track direct to Mackay at 4,500 ft was issued.

VH-TNU taxied at Mackay for Rockhampton and was cleared to track direct to Rockhampton, on the 143 radial. VH-RJE requested descent and was cleared to 3,000 ft. VH-TNU reported having left 1,700 ft on climb to FL150 and was transferred to the sector 7 frequency. VH-RJE was then asked to report crossing the coast. (The aerodrome controller expected the aircraft to cross the coast about 12 NM from Mackay on the Shute Harbour track.) The pilot reported that he was over land and approaching Hay Point (about 9 NM SE of Mackay). After the controller confirmed this position he immediately informed the sector 7 controller of the confliction with VH-TNU.

In the meantime, the sector 7 controller had observed VH-RJE on radar and was seeking confirmation of that aircraft's altitude.

By the time VH-TNU had passed 4,000 ft on climb, lateral separation between it and VH-RJE was 4 NM. Although VH-RJE had been displayed on radar to the sector 7 controller prior to this time, it had not featured in the controller's planning as it was outside controlled airspace.

For aircraft flying between Rockhampton and Mackay, laterally separated tracks had been developed. VH-TNU had planned via the western route but was given the direct track. VH-RJE had planned and tracked via the direct track.

A Cessna 152, VH-XPG, was sequenced for landing on runway 12 at the same time as a Boeing 747, VH-EBY, was sequenced for runway 15. A separation breakdown occurred when both aircraft converged towards their respective runways and the Cessna 152 was instructed to go around.

The approach radar controller had previously co-ordinated the landing of XPG on the non-duty runway 12. The aircraft's position in the landing sequence had not been determined, but would be close to that of EBY. From the aerodrome controller (ADC) position, XPG was radar observed just inside 4 NM final for runway 12 as the pilot of EBY contacted the tower at 6 NM final for runway 15. XPG was not on tower frequency; the expectation being that the aircraft would sequenced (by approach) to land behind EBY.

With EBY at approximately 2 NM final, XPG was continuing the approach at approximately 1 NM final and the pilot was not yet in contact on the tower frequency. An attempt was made to establish whether the pilot of XPG was on the tower frequency, and this proved negative. Instructions were then issued to the approach controller to send XPG around immediately. Traffic advice was issued to the pilot of EBY as the pilot of XPG made the missed approach.

The approach controller did not ensure that separation was maintained between EBY and XPG when the latter was cleared to leave the western VFR route on a visual approach for runway 12.

The approach controller should have arranged for the provision of visual separation by the ADC or issued instructions to establish and maintain lateral separation between the two aircraft prior to radar separation reducing to less than the standard of 3 NM.

The controller did not appreciate the implications for maintenance of separation when he cleared the pilot of XPG to track for final for runway 12 and to make a visual approach. The controller became distracted with other traffic considerations and did not maintain an adequate scan of the radar display. The flow controller had been advised of the inclusion of XPG in the traffic sequence.

The flow controller was satisfied that XPG could be included in the traffic sequence without detriment to other aircraft; subject to the approach controller providing final sequencing. The approach controller did not ensure that adequate separation and sequencing was applied between the two aircraft.

Cairns ATS is developing amended flow/sequencing instructions which will include procedures for aircraft arriving to either runway 15 or12, or the runways concurrently.

This was the first occasion on which the pilot had sprayed the sugar cane paddock. A briefing and an area map were obtained from the property owner. The pilot conducted a power line inspection and found three lines, all that had been brought to his attention. During the first spray run he noticed sparks at the propeller as an unseen set of three wires was cut. He returned to the take-off point and found that only the propeller had been damaged. The wires struck had not been seen at all. The relevant poles were hidden in trees on each side of the paddock.

The aircraft was conducting an ILS approach to Townsville, which was under the influence of Cyclone Justin, centred about 180 km north. Weather conditions for the approach were a strong, gusting crosswind, moderate to severe turbulence, and heavy rain.

At the start of the approach the aircraft was high on the glideslope. As the approach progressed the aircraft descended until it was well below the glideslope. The first officer called the flying pilot's attention to the rate of descent, which was up to 3,000 ft/min. A short time later, when the aircraft was at 780 ft above ground level, about 500 ft below the glideslope, and with a descent rate of 2,000 ft/min, the first officer called for a go-around. The captain applied power, and the descent was stopped at about 700 ft above ground.

The aerodrome controller cleared the aircraft to climb to 3,500 ft for a further approach. However, the aircraft levelled initially at 4,000 ft before a descent to 3,500 ft was carried out. The aircraft landed off the second approach, conducted using the autopilot coupled to the ILS.

Following the take-off with 850 L of chemical for another spray task, the engine began to vibrate and lose power. The pilot dumped the load and conducted a forced landing into a paddock about 4 km from the departure airstrip. During the landing one main landing gear leg was torn off, the wings were creased, and the propeller was bent rearwards. After an examination of the engine the pilot found that the number 6 cylinder had cracked between the spark plug holes.

The helicopter was in a steady cruise at 80 kts at 1,500 ft above ground level when the pilot heard a loud bang. He immediately initiated auto-rotation and believed that there had been a failure of the tail rotor drive. The pilot attempted a landing in the nearest clear area but the nature and slope of the terrain coupled with some rotation of the helicopter resulted in it rolling over and sustaining severe damage during the landing.

Examination of the helicopter revealed that the intermediate flex plate failed. This flex plate consists of the front and rear yokes plus the flex plate itself, all joined by four bolts. The examination found that one of the two front lugs was missing. The adjoining flex plate lug was present and bent forward. The bolt joining the missing front yoke lug to the adjoining flex plate lug was also not present. Neither the bolt nor the front yoke lug were found at the accident site.

The hole in the flex plate lug, opposite the missing front yoke lug, was worn and enlarged suggesting that, after the bolt was liberated, the shaft's axis of rotation changed. Such an event would have led to failure of the tail rotor drive and given the symptoms described by the pilot.

The pilot had conducted a brief pleasure flight. He intended to land to the west on a 330 m grass airstrip on his own property. The strip ran east west with a 12.5 degree upslope to the west. He estimated the wind components to be 5 kt headwind and 15 kt crosswind. However, on short final, the aircraft encountered moderate turbulence and windshear. The pilot elected to overshoot, but because of the steep upslope, this required a turn north or south. He advised that from past experience in PNG, having landed on many bush strips, he would normally have turned into wind during an overshoot into a one-way uphill airstrip. However, on this occasion he inadvertently turned downwind and encountered more windshear and loss of airspeed.

With the aircraft facing downwind and very low in airspeed, he elected to land straight ahead in the paddock. During the latter part of the landing roll the aircraft nosewheel collided with a rock and the aircraft overturned. 

The pilot subsequently advised that the aircraft had recently undergone a complete overhaul and that had not contributed to the accident.

After completing pre-take-off checks in the northern runup bay for runway 29, the pilot of the Cessna 180 began taxying to the runway 29R holding point. As the aircraft moved forward and turned left onto taxiway K5 he saw a Piper Seneca to his right, in very close proximity, taxying along K5. The pilot of the Cessna braked sharply, however the nose of the aircraft pitched down, resulting in the propeller of the Cessna striking the left tailplane of the Seneca.

Weather conditions were fine, with no obstacles to visibility. Because of the high nose attitude of the aircraft and associated obstruction by the instrument panel, the pilot of the Cessna 180 did not see the approaching Seneca as he left the holding bay. When he did see the Seneca, he had insufficient time to prevent a collision.