When the aircraft encountered icing conditions at 3000 feet on climb the following annunciator lights illuminated:

• #2 INTAKE LOW PRESSURE
• #2 AIR FAULT
• #4 AIR FAULT
• #2 AIR VALVE
• #4 AIR VALVE

The aircraft returned to Melbourne for a normal landing. Maintenance replaced the #2 engine intake low pressure switch and carried out satisfactory ground runs. During later testing the intake low pressure switch was found to be serviceable.

Further checks were carried out on the performance of the number 2 and 4 engines during the overnight service, but the fault was unable to be reproduced. The flight data recorder was not examined to ascertain the flight and engine parameters at the time of the incident.

Maintenance noted that low duct temperatures will give an AIR LOW TEMP warning which will cause the AIR FAULT and AIR VALVE lights to come on. Maintenance advised that it was necessary to maintain 90% N2 to obtain satisfactory airframe anti-ice performance thereby maintaining adequate intake duct temperatures.

Maintenance asked that if the fault reappeared the pilots should supply the N2 figures. The fault has not reappeared.

Significant Factors

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

1.The aircraft was flown in icing conditions with thrust settings below those required to maintain adequate anti-ice performance.

2.The reason why this occurred was not established.

The left main landing gear indicated unsafe after the pilot selected gear down. The gear was recycled, and the emergency extension procedure applied with the same result. During the subsequent landing, as the aircraft slowed, the left main gear collapsed.

Inspection revealed that the left main gear trunnion pivot pin had partially seized. This had prevented both the normal and emergency extension. Although the component had been lubricated as required by maintenance procedures, the lubricant had not penetrated the full length of the pin, leading to the partial seizure.

The purpose of the flight was dual training for a private pilot on the aircraft type. On arrival overhead the aerodrome the wind was assessed as a north-westerly at 10 - 15 knots. The pilot joined the circuit for runway 35. The instructor reported that the approach was normal other than being slightly high, but this was corrected by the pilot. Touchdown was reported to be on the main wheels first at approximately 65 - 70 knots. As the nose contacted the ground, the aircraft began to veer substantially to the left. The instructor took control using right rudder but with no effect. The aircraft swerved off the runway and the nose gear collapsed.

A post-accident inspection showed scrub marks on the nose gear and left main gear tyres consistent with left yaw and right rudder application. The nose gear trunnion had failed in sideways overload. A post-accident inspection of the aircraft did not reveal any mechanical defects that may have led to the accident.

VH-TQR departed Sydney on Runway 25, Radar 3 departure, and was cleared to climb to an initial altitude of 5,000 ft, on a radar heading of 240 degrees. The altitude restriction was to provide vertical separation with inbound traffic. The aircraft was under the control of the Departures South Controller.

VH-OGB was inbound to Sydney from the southwest, being radar vectored by the Approach South Controller for a left circuit to runway 34L, and had been assigned a heading of 050 degrees, on descent to 5,000 ft. This placed VH-OGB and VH-TQR on crossing tracks with a convergence angle of about 170 degrees. The crew of VH-OGB received a Traffic Alerting and Collision Avoidance System (TCAS) Traffic Advisory warning which indicated an aircraft climbing towards VH-OGB, 1,800 ft below. They expected the TCAS traffic would level off 1,000 feet below them. As VH-OGB was in visual meteorological conditions, a lookout was commenced for the traffic. VH-TQR was not fitted with TCAS. The conflicting traffic was then observed on TCAS, climbing some 500 feet below VH-OGB.

The Approach South Controller instructed VH-OGB to turn right heading 090 degrees to position for landing on runway 34L. The other traffic passed off the TCAS screen behind VH-OGB, without the crew sighting the aircraft. Minimum vertical separation indicated by TCAS was 300 ft. Neither the Departures South nor Approach South controller recognised the traffic conflict, and no traffic information was passed to either aircraft.

Recorded radar data confirmed the conflicting traffic was VH-TQR which passed within 1 NM of VH-OGB, with a minimum vertical separation of 500 ft. The minimum separation standard required for air traffic control purposes was 1,000 ft vertical or 3 NM lateral.

New air traffic handling procedures for departing and arriving aircraft were introduced at Sydney one week prior to the incident. Among the changes was an alteration to the vertical division for airspace in the vicinity of Sydney Airport between the Departures and Approach Controllers. The controller who occupied the Approach South position had minimal familiarity with the new procedures. He inadvertently reverted to old procedures and incorrectly assigned VH-OGB an altitude of 5,000 ft instead of 6,000 ft. Neither the Departures South nor the Approach South controller had been monitoring the vertical progress of their respective aircraft, at the point at which the flight paths crossed.

The flight was a night navigation exercise associated with the pilot-under-instruction's (PUI) training for the award of a Night Visual Meteorological Conditions rating. The pilots had completed a briefing before departure, but its content was restricted to flight planning aspects only.

An enroute landing had not been planned, but the instructor decided that the PUI should carry out a touch and go landing at Narrogin when he saw that the north/south runway flare path was illuminated.

The flight was the PUI's third night flying training flight and was his first away from Jandakot at night. Aircraft attitude and directional control at night is enhanced, in the Jandakot area, by the high level of ground lighting which provides a natural horizon. In areas where ground lighting is not available the pilot must rely on the information provided by the aircraft's instruments and in particular the artificial horizon. During the take-off from Narrogin the PUI used an incorrect attitude and directional maintenance technique when he initially selected a wings level, and 10 degrees nose up attitude on the artificial horizon but then attempted to maintain that attitude by holding an indicated airspeed of 75 knots without further reference to the artificial horizon. This resulted in the aircraft entering a left hand descending turn.

The instructor allowed his attention to be drawn away from his pilot monitoring role by an apparently subtle engine r.p.m. fluctuation shortly after the touch and go landing and did not detect the pilot's incorrect technique until too late. When the instructor did perceive that the aircraft was near the ground and took control, there was insufficient time to recover before the aircraft collided with a tree. The aircraft continued to fly without any obvious damage or control problems, and the instructor elected to continue to Jandakot, expecting to have landing gear problems on arrival. These did not eventuate, and the aircraft landed safely at Jandakot.

The B737 was inbound to Coolangatta, heading 340 and on descent to 7,000 ft. This heading would take the aircraft across the extended centreline of runway 14. The SA226 had been cleared to climb to 5,000 ft on runway heading after take-off from runway 14. The B737 was subsequently cleared to 2,000 ft to join right downwind for runway 14. Shortly after the SA226 levelled at 5,000 ft, the B737 passed in the opposite direction approximately 1.5 NM east and 500 ft below the SA226. The separation standard required was 3 NM horizontal/1000 ft vertical separation.

The responsible controller was under a moderate to high workload in the period leading up to the incident. In addition to other departing and arriving traffic, there was traffic to the north of Coolangatta being handed off to Brisbane and a parachuting aircraft awaiting run-in for a drop near the aerodrome.

It appears that the high workload and other traffic considerations distracted the controller to the extent that he forgot about the SA226, at least temporarily. The appropriate technique would have been to provide separation assurance by way of the departure clearance. The controller indicated that he may have been suffering a degree of fatigue at the time of the incident, and this may have affected his performance.

The pilot reported that the approach and landing were normal with touchdown at 70 kts. Shortly after touchdown the aircraft began to yaw to the right. The pilot used full left rudder and some differential braking in an attempt to stop the yaw but was unsuccessful.

As the aircraft approached a runway marker (car tyre) the pilot applied full braking, raised the nose to clear the tyre and shut the engine down. The aircraft cleared the tyre but the nosewheel subsequently collided with a dip in the ground and collapsed. The left tyre blew out at the same time.

Subsequent inspection failed to disclose the reason for the yaw. The wind was light at the time of the landing.

The pilot reported that during the take-off run he became apprehensive about the runway distance remaining. The take-off was abandoned but the aircraft collided with a fence.

The pilot said that the runway surface was covered with small pebbles which appeared to reduce the braking efficiency. He steered the aircraft to the right to avoid a fence. The aircraft was almost stationary when it struck the fence.

Following take-off from runway 01 at Townsville, the military aircraft, Stallion 080, was instructed to turn right and climb to flight level (FL) 120. VH-TNX departed from the same runway and was instructed to turn left to intercept the track to Cairns. When Stallion 080 reported at FL120 the Townsville controller requested the level of VH-TNX. The pilot of that aircraft replied passing FL110 and was instructed to report leaving FL130, and to climb at the best rate of climb. The controller then asked Stallion 080 to report sighting VH-TNX, after a short delay the pilot reported that the aircraft was in sight and that he would maintain separation visually.

Subsequently, Stallion 080 passed VH-TNX on the left side at about the same level, approximately 200 metres away.

The method by which the Townsville controller attempted to maintain separation between the two aircraft was not correct for the situation. The Manual of Air Traffic Services does not allow for one aircraft to visually separate itself from another aircraft at the level the aircraft were operating. However, there were a number of other techniques, that could have been employed by the controller, to maintain the required separation between the two aircraft.

The pilot of Stallion 080 reported that he was unable to manoeuvre his aircraft to pass further from VH-TNX as this would have required abrupt action and may have resulted in injury to standing passengers in his aircraft.

The aircraft was being flown on an instructor standardisation flight which included the demonstration of a precautionary landing on a grass airstrip.

Prior to landing, the pilot in command who was also the chief flying instructor, carried out an inspection of the strip from a height of 500 feet above ground level (AGL). During the first run he noticed what appeared to be a series of ruts along the strip and decided to carry out a second run at a lower height. Before descending to 50 feet AGL, the pilot lowered the landing gear as a safety precaution. During the second run, he confirmed that the surface appeared suitable for a landing. The landing gear was retracted, and the aircraft was climbed back to 500 feet AGL for the landing circuit.

The pilot reported that he carried out the before landing checks on downwind but for reasons unknown, neglected to carry out a final approach check. When the throttle was closed during the flare, the landing gear warning horn sounded. The pilot applied full power to go round but then closed the throttle almost immediately when he felt the propeller strike the ground. The aircraft settled onto the strip and slid to a halt with the landing gear retracted.

Although the pilot in command had failed to lower the landing gear this went unnoticed by two other instructors who occupied the front right and rear right seats. It was reported that sunlight shining onto the landing gear indicator lights might have created the impression that the green lights were illuminated.