Champion Aircraft Corp 7GCAA, VH-TUF

FACTUAL INFORMATION¹

Sequence of events

On 15 May 2005 at 1535 Central Standard Time, an American
Champion Corporation Citabria 7GCAA aircraft, registered VH-TUF
(TUF), took off on a local flight from a private airstrip at
Stonefield, SA. On board were the pilot and a passenger, who was
also a licensed pilot. Dual controls were installed in the
aircraft. The aircraft was observed by witnesses at the airfield to
pull up into a steep climb after becoming airborne, before
apparently stalling and impacting the ground. Both occupants were
fatally injured. The aircraft was destroyed by impact forces and a
post-impact fire (see Figure 1).

Figure 1: View of the wreckage looking west

The pilot had been at the Stonefield airstrip during the weekend
with other pilots and aviation enthusiasts. On the morning of the
accident, the pilot had conducted a short flight in TUF, which
included a flypast at a nearby airstrip that was witnessed by two
experienced commercial pilots. They described observing the
aircraft flying at 'high speed', approximately 20 ft above ground
level (AGL) over a taxiway, before pulling up into a vertical
climb. The pilot then performed a stall turn and the aircraft was
observed to enter a spin or spiral before recovering at a height of
about 200 ft and continuing on its original heading.

After returning to Stonefield airstrip, the pilot was required
to transport a passenger to Parafield Airport, SA. While at
Parafield, the pilot arranged for the aircraft to be refuelled with
62 L of AVGAS. The refueller reported to investigators that that
quantity of fuel filled the tanks².
After returning to Stonefield airstrip again, the accident pilot
was reported to have undertaken a flight with another pilot in a
different aircraft, during which the accident pilot had
demonstrated a number of aerobatic manoeuvres to the other pilot.
The accident pilot then undertook a further flight in TUF with the
same passenger as the previous flight, and demonstrated a number
aerobatic manoeuvres again.

After discussion with other people at Stonefield, the accident
pilot decided to conduct a further local flight, and the same
passenger from the previous two flights was invited as a passenger
again. Witnesses observed the passenger in the rear seat and the
pilot in the front seat. After engine start-up, the pilot performed
a turn on the ground of more than 360 degrees before taxying on the
north-east strip without performing an engine run-up. The aircraft
engine was heard increasing in RPM prior to the aircraft commencing
a downwind takeoff into the north-east. After becoming airborne,
the aircraft was observed to remain at approximately 10 ft AGL
until it reached a fence line to an adjoining property at the end
of the strip. At about this point, the aircraft was observed to
enter a near vertical climb. At an estimated height of 500 ft AGL,
the aircraft appeared to aerodynamically stall in the vertical
attitude, before entering a right hand spin. The aircraft completed
one and a half turns in the spin, before it appeared to almost
recover just before impacting the ground.

Personnel information

The pilot was 63 years old and held both commercial and private
pilot licences for aeroplanes. He had successfully completed an
Aeroplane Flight Review in August 2004. The pilot had a total of
2,848 hours experience, 2,746 hours of which was as pilot in
command in single-engine fixed-wing aircraft. The pilot was an
experienced aerobatic pilot in New Zealand. He did not hold a low
level aerobatic approval from the Australian Civil Aviation Safety
Authority (CASA).

The pilot had undergone medical treatment for a terminal illness
and, at the time of renewal of his Class 1 medical certificate,
informed his Designated Aviation Medical Examiner (DAME) of this
illness. At the time of that examination, the pilot's Class 1
medical certificate had expired. However, his Class 2 medical
certificate was not due to expire until December 2005.

The DAME did not reissue either the Class 1 or Class 2 medical
certificate and referred the matter to CASA. An assessment by CASA
medical staff confirmed that the pilot's medical condition
precluded him from flying as pilot in command. The pilot appealed
to CASA regarding that adverse assessment and was advised verbally
and in writing by CASA of his obligations under Civil Aviation
Safety Regulations 67.265³ and
67.270⁴ until the outcome of the
review of that appeal was known.

Although a review of the assessment was commenced, CASA did not
cancel or suspend his Class 2 medical certificate while that review
process was being completed. CASA advised the Australian Transport
Safety Bureau (ATSB) that it was normal procedure to only cancel or
suspend a certificate after all specialist medical information was
received and all options to mitigate safety risks to air navigation
were considered. During the period his medical condition was under
review, the pilot logged more than 20 hours in aircraft as pilot in
command.

In addition to the flights made on the day of the accident, the
pilot had flown to Stonefield from Parafield during the previous
day. Prior to this, the pilot had worked during the days at his own
business conducting non-aviation activities and was reported to
have been well rested.

Several pilots reported that the pilot had regularly performed a
similar low level aerobatic manoeuvre to that which preceded the
accident. A chief flying instructor who had known the pilot,
reported that he had observed the pilot perform this type of
low-level aerobatic manoeuvre several times in the past. During the
investigation, he advised investigators that he was concerned about
the safety of the manoeuvre and had warned the pilot about the
dangers of performing it.

Aircraft information

A 100-hourly maintenance check was completed on the aircraft 3
days prior to the accident, at which time the aircraft had recorded
2,451.14 total time in service (TTIS). The maintenance release was
unable to be located and was probably burnt in the wreckage. As a
result, the time flown subsequent to that check could not be
accurately determined.

Weight and balance calculations made using estimated fuel and
occupant weights, determined that the aircraft may have been as
much as 20 kg over the maximum all up weight, and that the centre
of gravity (CoG) was rearward of the aerobatic limit, but within
the normal operating range.

Meteorological information

There was no terminal aerodrome forecast for the private
airstrip. However, the area forecast indicated that the wind at
2,000 ft was 150 degrees true at 15 kts. Other pilots who flew into
Stonefield that day reported that the ceiling and visibility was
acceptable for visual flight and that the wind was a southerly at 8
to 10 kts at ground level. However at 500 ft AGL, the wind was
reported to be a southerly at approximately 30 kts. The temperature
was reported to be 19 to 20 degrees Celsius.

Wreckage information

The aircraft struck the ground in a 40-degrees nose-down
attitude with the left wing low, and came to rest facing the south
west, 22 m from its initial impact point. Damage to the propeller
indicated the propeller was rotating at impact. The aircraft was
destroyed by severe impact forces and a post-impact, fuel-fed
fire.

Two persons attempted, unsuccessfully, to extinguish the fire
with hand-held fire extinguishers. The fire was subsequently
contained by local fire fighters. The accident was not
survivable.

The engine was removed and examined at an approved engine
overhaul facility under supervision of the ATSB. No anomaly or
defect was found in the engine and it was determined that the
engine was capable of normal operation prior to the accident.

The stall warning system on the aircraft was examined. The
wing-mounted air vane switch that actuated a warning horn/light in
the cockpit was found to have one of the electrical leads
disconnected, rendering the stall warning system inoperative. The
lead had been safely secured and appeared to have been deliberately
disconnected. Subsequent testing of the stall warning system found
that when wired correctly, it was capable of functioning normally.
The investigation was unable to determine when, or by whom, the
stall warning system was deactivated. The stall warning device
gives an indication to the pilot of an impending aerodynamic stall
condition.

There was no evidence of any other mechanical defect that could
have contributed to the accident.

Medical and pathological

Results of post-mortem and toxicologic testing of the pilot did
not reveal any evidence of any sudden incapacitating condition that
could have contributed to the accident.

Fuel

A small sample of fuel was taken from the aircraft wreckage,
however, this fuel was contaminated by fire fighting agents, and
could not be used as a reliable pre-fire indicator of fuel quality.
The aircraft had been refuelled at Parafield earlier that day, but
the batch from the tanker was unable to be tested, as it had been
mixed with a new batch of fuel. The investigation determined that
fuel from the batch from which TUF had been refuelled had also been
used to refuel more than 12 other aircraft. There were no reports
of fuel contamination or fuel related problems from those
operators.

Aircraft manufacturer's information

The aircraft manufacturer was asked to comment on aspects of the
aircraft's performance and handling. Their test pilot reported
that:

flight above gross weight would decrease takeoff performance and
increase stall speed

In respect to the exceedance of the rearward aerobatic CoG datum,
the test pilot reported that:

the CG [centre of gravity] exceeded the aft aerobatic limit… but
was within the normal category of 18.2. I do not feel this
contributed to the pilot's ability to control or recover the
aircraft.

The manufacturer reported that:

the decision to conduct a low altitude aerobatic maneuvre [sic]
with insufficient airspeed resulted in the subsequent
stall/spin.

Only those investigation areas
identified by the headings and subheadings were considered to be
relevant to the circumstances of the occurrence.
Full tanks 147 L.
Essentially, this regulation
requires a pilot in the accident pilot's circumstances to be
cleared by a DAME before exercising the privileges of a
licence.
This regulation places the onus on a
pilot not to exercise the privileges of a licence if the pilot is
aware that he or she has a medically significant condition.

The pilot performed a manoeuvre that resulted in a loss of
control at a height and speed that was insufficient to permit
recovery before the aircraft hit the ground.

The pilot was reported to have conducted a similar low-level
manoeuvre to that which preceded the accident on several previous
occasions. On that basis, the investigation team considered that it
was unlikely that the passenger was at the controls of the aircraft
at the time of the accident. The manoeuvre left little or no margin
for error and required sound judgement and skill. Although the
pilot may have possessed those skills, no evidence was found of his
ever having undertaken the appropriate check to assess those skills
and obtain approval to conduct low-level aerobatic manoeuvres.

Repetition of the manoeuvre over a period of time may have led
to the pilot gaining a false sense of security and may have led to
the pilot becoming complacent about the inherent dangers involved
with such manoeuvres. The manoeuvre performed by the pilot earlier
that day at another location was commenced from a 'high-speed'
flypast. The associated energy would have allowed the aircraft to
convert speed to height and climb higher and attain a greater
altitude for recovery than the manoeuvre performed during the
accident flight. That manoeuvre was commenced from a take-off roll
that did not use the full runway length available. When combined
with a tailwind component, it was unlikely that the aircraft
attained adequate airspeed to safely complete the intended
manoeuvre by the end of the strip. It was also possible that the
pilot was unaware of the windshear or had not considered its affect
on the aircraft's climb performance.

Although the aircraft appeared to have stopped spinning to the
right just before impact, the pilot had insufficient height to
avoid a collision with the ground. Had the stall warning been
operating, it could have provided the pilot with an earlier
indication of the stall condition and thus enabled him to initiate
a recovery earlier in the development of the manoeuvre.

The affect of the pilot's medical condition on his judgement or
decision-making could not be determined. However, some aspects of
the pilot's behaviour were not consistent with compliance with
rules and regulations or good airmanship. These included conducting
low-level aerobatics without approval, ignoring concerns expressed
by peers, operating with an unserviceable stall warning indicator
and ignoring weight and balance limitations. Furthermore, the pilot
flew the aircraft knowing that he was suffering from a medical
condition that was being reviewed by the Civil Aviation Safety
Authority (CASA), and having been advised by CASA that he was not
to fly until the results of the review were known. Disregard for
the rules governing the conduct of flight and the operation of the
aircraft removed safety defences that were established to prevent
this type of accident.

On 15 May 2005, at 1535 Central Standard Time, an American
Champion Corporation Citabria 7GCAA aircraft registered VH-TUF,
with a pilot and passenger, took off from Stonefield private
airstrip in South Australia for a local private flight. Shortly
after becoming airborne, the aircraft crashed. Both occupants were
fatally injured. The aircraft was destroyed by impact forces and a
post impact fire.

After start up, the pilot performed a turn on the ground of more
than 360 degrees before taxying on the north-east strip. The
aircraft engine was heard powering up on the strip into the
north-east and shortly after became airborne. After becoming
airborne, the aircraft was observed to remain approximately 10 feet
above the strip, and remained at that height until the end of the
strip. At about this point, the aircraft was observed to enter a
near vertical climb. At an estimated height of 500 feet above
ground level, the aircraft stalled in the vertical position, before
entering a right hand spin. The aircraft completed one and a half
turns in the spin before it appeared to recover. At the point where
the aircraft appeared to have recovered from the spin, it impacted
the ground.

The investigation determined that the aircraft on the accident
flight was 20kg over maximum all up weight (MAUW). The increased
weight would have the effect of increasing the stall speed of the
aircraft, thereby reducing its performance. It was also determined
that the pilot took off north-east with a quartering down wind
component, and attempted a vertical climb with a wind gradient of
approximately 30kt and at 500 feet from the south, above ground
level. This wind gradient would have significant impact on the
aerodynamic performance of the aircraft, and the pilot may not have
achieved the height he intended before it stalled.