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.
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.
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.
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.
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.
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.
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:
In respect to the exceedance of the rearward aerobatic CoG datum, the test pilot reported that:
flight above gross weight would decrease takeoff performance and increase stall speed
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 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.
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.
|Date:||15 May 2005||Investigation status:||Completed|
|Time:||1535 hours CST|
|State:||South Australia||Occurrence type:||Collision with terrain|
|Release date:||20 April 2006||Occurrence category:||Accident|
|Report status:||Final||Highest injury level:||Fatal|
|Aircraft manufacturer||American Champion Aircraft Corp|
|Type of operation||Private|
|Damage to aircraft||Destroyed|
|Departure point||Stonefield, SA|
|Departure time||1535 hours CST|
|Role||Class of licence||Hours on type||Hours total|