Sequence of events
The Cessna A152 Aerobat aircraft was engaged on an aerobatics
training flight with the pilot the sole occupant of the aircraft.
The pilot was practising for an aerobatic competition and had been
having problems conducting stall turn manoeuvres.
Before the accident flight, the pilot had completed an aerobatic
practice flight with an instructor. The pilot then decided to fly a
solo flight to practise stall turns without the effect of a second
person's weight on aircraft performance in aerobatic manoeuvres. He
then intended to practise his full aerobatic sequence, which the
instructor later stated was well within the pilot's capabilities.
Between flights the pilot refuelled the aircraft and consumed a
bottle of soft drink.
After takeoff for the solo flight, the pilot discussed with his
instructor by radio, his intentions for the flight and the
criticisms of his manoeuvres during the dual flight. The instructor
later reported that during the discussion, everything concerning
the pilot and the aircraft seemed normal.
Witnesses some distance away heard the aircraft fly over. They
later heard a thump and noticed smoke rising from the same
direction as the source of the sound. There were no witnesses to
the impact.
Wreckage examination
The wreckage was contained within a relatively small area, apart
from two sections of fuel tank and the associated wing that were
found about 40 m away. Most of the aircraft had been consumed by a
post-impact fire.
Examination of the accident site revealed that the aircraft had
impacted the ground in balanced flight at high speed in an attitude
of approximately 70 degrees nose down. The engine was producing
high power at impact. Examination of the wreckage did not reveal
any technical defect that would have contributed to the
accident.
Pilot
The pilot was 61 years of age and had been flying since 1979. He
held a Private Pilot Licence (Aeroplane), and a valid Class 2
medical certificate. He had accrued a total of 893.3 hours flying
experience, including 7 hours in the last 90 days, probably all on
type. In the last 30 days, he had flown 1.3 hours, all on the day
of the accident. Since 1982, the pilot's principal interest had
been aerobatics, and in recent years he had become involved in
competition aerobatic flying. Since November 1994, he had held a
CASA approval to conduct aerobatics down to 1,500 ft AGL. He had
completed his most recent biennial flight review on 26 June
2000.
The pilot had a long history of hiatus hernia and taken
medication for it but had not undergone surgery. At the time of the
accident, he was not taking prescribed medication. For about 10
years, he had been prone to fits of coughing after eating and
drinking. During these attacks, his ability to perform other tasks
was impaired. About 45 minutes before the dual flight, the pilot
had eaten a burger and chips. During the dual flight, he had
suffered a fit of coughing during which time his attention to
flying the aircraft was reduced.
Toxicological examination of the pilot revealed the presence of
the drug doxylamine, at a concentration of 4.7 mg/kg in the liver.
The finding was reported as `semiquantitative' with a possible
error of 20 percent. However, regardless of any error, the
pathologist regarded the concentration as sufficiently high to
possibly affect the pilot's ability to fly the aircraft.
Medical information revealed that makers of pharmaceutical
products usually include doxylamine with other agents such as
paracetamol and codeine in strong analgesic medication for such
conditions as migraine. In isolation, doxylamine is classified as
an anti-histamine, but it has strong anti-emetic properties useful
for treating motion sickness, nausea and similar conditions. It is
also a drying agent used in a number of non-prescription cold and
flu preparations. However, either alone or in conjunction with
other substances, doxylamine can cause drowsiness, visual
disturbance and can contribute to disorientation.
