Accident Sequence
A flight arranged to transport a critically injured patient to a hospital in Brisbane ended in a crash shortly after takeoff. The pilot experienced difficulty starting one engine, but witnesses reported normal engine sounds as the aircraft began taxiing from the parking area. At 0310 hours, the pilot contacted Brisbane Flight Service Unit, reporting that the aircraft was taxiing. He indicated he was in a hurry and would provide flight details after takeoff. Two minutes later, he advised that takeoff was commencing from Runway 14. No further transmissions were received.
The aircraft became airborne and soon entered a fog bank. Witnesses subsequently reported hearing impact sounds. Investigation revealed that the aircraft collided with a tree 800 metres beyond the aerodrome boundary, while tracking about 10 degrees to the right of the extended runway centreline. It continued on the same heading for another 177 metres before striking the ground. The wreckage was almost entirely consumed by fire.
Investigation
The extensive fire damage hampered the investigation. The surviving passenger believed the aircraft was on fire before the collision, but no other evidence of an in-flight fire could be obtained. It was considered possible that the survivor's recall was affected by the impact and fire, a common occurrence among accident survivors.
Examination of the elevator trim control jack found it in the full nose-down position, but it could not be established whether this was the pre-impact setting. Such a position could indicate either a runaway electric trim or that the pilot, in haste, did not correctly set the trim for takeoff.
The aircraft was known to have an intermittent fault in the engine fire warning system, which caused the warning light to illuminate and fire bell to sound, usually just after becoming airborne. The pilot was aware of this fault. If the fault occurred as the aircraft entered the fog, the pilot's attention may have been temporarily focused on cancelling the warnings, diverting him from monitoring the primary flight attitude indicator, with no external visual references.
Another possibility was that the pilot, if not monitoring flight instruments, suffered a somatogravic illusion. This illusion occurs during acceleration, combining acceleration and gravity forces to create a sensation of nose-up pitch. Pilots may counter by applying forward elevator control, potentially descending into the ground. The pilot's susceptibility may have been increased by a bronchial or influenzal infection.
Possible Factors
Although no firm conclusion was reached, the following factors were considered relevant: 1. The pilot was making a hurried departure; elevator trim may not have been correctly set, and engines may not have reached normal operating temperatures. 2. Shortly after liftoff, the aircraft entered a fog bank, depriving the pilot of external visual references. 3. The defective engine fire warning system could have distracted the pilot at a critical stage. 4. An electric elevator trim malfunction or internal fire could have led to loss of control. 5. The pilot may have experienced somatogravic illusion, inadvertently flying into the ground, with increased likelihood due to his infection.