Covering form of preliminary or final report
Back| Date of event: | 2023.09.12 |
|---|---|
| Incident number: | CZ-23-1072 |
| Report: | Final report |
| Place of event: | ATZ LKHV |
| Registration mark: | Air accident |
| Weight category MTOM:: | <2250 kg |
| Type of operation: | Recreational and sport aviation |
| Plane / SFM: | Sports flying machine |
| Type of plane / SFM: | EV-97 EUROSTAR SL |
| Health effects of event: | The fatal injuries |
| PDF document: |
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Description:
SUMMARY
Synopsis
On 12 September 2023, the AAII was notified of an air accident of the EV-97 EUROSTAR SL UL aircraft in the proximity of the Hořovice airport. The UL aircrew, a student pilot with an instructor on board, performed training flights on the circuit at LKHV. After touch-and-go landing on RWY 24, the UL aircraft continued to climb in the runway course. At about 50 m AGL, it stopped climbing and started a 180° right turn. During this manoeuvre, the UL aircraft wing stalled with a subsequent transition to a right spin. After less than one turn, it crashed at a steep angle into a garden house under construction on a plot of land at the southern edge of the village Tlustice. The UL aircraft was destroyed by an impact with the obstacle. Damage to third party property occurred. The pilots succumbed to their multiple injuries despite timely professional resuscitation at the accident site.
Factual Information
The instructor conducted preflight preparation with the student pilot, probably focused on training flights on the circuit with a touch-and-go landing and take-off. After inspection of the UL aircraft, take-off from RWY 06 at LKHV followed at 06:30:49. In the area of the first turn, they performed a 180° turn with the UL aircraft and after a touch-and-go landing on RWY 24, they continued flying on the right circuit of RWY 24. They performed a total of three training flights on the circuit with a touch-and-go landing and take-off. The crew extended the third circuit to approximately 5 km east of the RWY 24 threshold and continued in an approach to RWY 24 by manoeuvring along the extended runway centreline. After making a touch-and-go landing on the runway, they continued to take off with a subsequent slight climb in the course of 241°. At the point where the road connecting the village Tlustice with the town Hořovice crosses the western part of the runway used for aircraft taxiing, the UL aircraft stopped climbing at the GPS altitude of 1,342 ft and started a right turn. During the execution of the turn, the UL aircraft was gradually losing altitude and speed. Upon reaching the course of 335° and the GPS altitude of 1,308 ft, the UL aircraft wing stalled with a subsequent transition to a right spin. At 06:59:50, after less than one turn, it crashed at a steep angle into a garden house under construction on a plot of land with a family house at the southern edge of the village Tlustice.
Student Pilot’s Competence and Qualification
The student pilot was not fit to fly because the Commission did not find a medical certificate and there was no record of a medical examination in his personal report. He performed a training flight with an instructor on board according to the Ultralight Aircraft Pilot Syllabus approved by the LAA ČR. UL 3 states that a valid class 2 medical certificate is a prerequisite for commencing practical training. According to the practical training records in his personal report, he performed exercises 1 to 9 on the UL aircraft type SKYLEADER GP ONE smoothly and without problems. When piloting this type, his performance was stable and was rated mostly very well by both instructors. Since 18 August 2023, he continued his training on the EUROSTAR EV-97 type with piloting of which he had little experience. The Commission found no record of theoretical training for this UL aircraft type. The student’s personal report was not maintained by the instructor in accordance with the UL 3 Ultralight Aircraft Pilot Syllabus.
The Commission concluded that with respect to the student pilot’s current weight, this type of UL aircraft was not suitable for his training and that under the given conditions, the MTOW would be slightly exceeded even in the case of a solo flight.
Instructor’s Competence and Qualification
The instructor had flown on the type and had sufficient skills and experience with conducting flight training of student pilots. He had been training extensively, as evidenced by 75 h 10 min flown, including more than 200 flights in the last three months. His colleagues from the aero club described his behaviour as professional and further stated that he had followed approved procedures when training pilots and his priority was always flight safety.
The instructor was not qualified to fly because he was piloting the UL aircraft while intoxicated. Toxicological examination detected 0.77 g∙kg-1 of alcohol in the instructor’s blood and 1.15 g∙kg-1 of alcohol in his urine. At the time of the flight, the instructor was in the elimination phase of breakdown of alcohol consumed at an unknown time prior to the flight. The said level of alcohol in the blood impairs the sensory, motor and cognitive functions of the human body.
He did not comply with the UL 1 Terms of Operation of Air Recreational Vehicles. As PIC, he failed to comply with the UL operating limitations of the aircraft because he performed the flight with a maximum take-off weight exceeding the maximum take-off weight specified by the manufacturer and centre of gravity outside the authorised range. In addition, he violated the prohibition against operating an aircraft while under the influence of alcohol.
A comprehensive forensic medical examination revealed that the flight training was conducted and the UL aircraft was piloted by an instructor who was negatively affected by alcohol at the time of the accident. The instructor’s intoxication may have influenced his decision on the further course of the flight in connection with the power unit problems. As there was no complete engine shutdown, but a partial loss of engine power, the instructor probably decided to perform a 180° turn with the UL aircraft in order to use the 1,170 m long asphalt RWY 06 for the subsequent landing. By performing this manoeuvre in the event of engine failure during take-off, he did not comply with the UL aircraft Flight Manual. The incorrect decision not to use straight landing on the approximately 500 m long asphalt taxiway may have been influenced by the concern that a possible runway excursion onto the field in front of road 114 would damage the UL aircraft, making it impossible to continue with the scheduled training of the flight school students.
The instructor or student pilot was wearing plastic sandals with open heels. Experienced UL aircraft pilots have confirmed to the Commission that the use of this type of footwear is completely inappropriate for flight and in their experience they observed cases where the sole uncontrollably got under the foot control pedals. Subsequent handling of the loose footwear adversely affected the ability to safely control the UL aircraft.
The operator has always repaired all the defects on the UL aircraft recorded in the aircraft logbook. No record of engine performance problems was found.
The Commission learned about the engine problems from persons who had worked with the instructor in maintaining the UL aircraft. On 10 September 2023, there were problems with the engine power, which resulted in an emergency landing at the airport in Bubovice. The instructor performed a motor test followed by a safe overflight to LKHV. On the day before the accident, 11 September 2023, both carburettors were dismantled at the hangar site at LKHV. When inspected, small mechanical impurities were found at the bottom of the cups. Some parts were replaced and the fuel system was flushed. After these operations, a check flight was performed. Though the engine was not “in discrepancy” or “stalling” in flight, the instructor did not find the engine running smoothly. The entire fuel system was flushed again and the air intake to the tank was checked. After that, he carried out an approximately 10-minute engine test followed by a 15-minute check flight aimed at verifying the engine operation in different flight modes. Everything went smoothly and the instructor continued in the planned training of his student pilots on 12 September 2023.
During the event flight, the maximum take-off weight and centre-of-gravity position specified by the manufacturer were not adhered to; therefore, sufficient control range for safe piloting of the UL aircraft was not secured. The maximum take-off weight of the UL aircraft was exceeded by more than 97 kg. The centre-of-gravity position was outside the prescribed range beyond the front limit at 19.58% SAT.
It was also possible to determine from the wreckage of the UL aircraft that its technical condition did not show any anomalies. The damage to the UL aircraft was caused by impact with a fixed obstacle with subsequent transfer of forces to the fuselage and landing gear structure. After the air accident, all parts of the airframe were located in the impact area. It was not proven that any part of the UL aircraft had been separated before its fall on the ground. No UL aircraft control surface was missing. All the damage to basic supporting and control elements corresponded to the cause of an impact with an obstacle on the ground. The wreckage investigation revealed no defects or damage that could have occurred before the accident.
Upon subsequent technical investigation of the UL aircraft wreckage at the place of its deposition in the AAII hangar, technical investigation did not detect any facts that would indicate that the air accident was caused by a technical defect of the UL aircraft.
At the time of impact with the ground, the propeller of the UL aircraft was spinning. All three blades of the propeller made of composite material were broken off from the hub at the root of the blade. It is clear from the witness statements that the engine was not working properly during the critical phase of the flight. According to the investigations and tests carried out, the malfunctioning of the engine was probably caused by poor-quality fuel containing mechanical impurities, which could have caused the unreliable operation of the carburettors.
The instructor probably conducted preflight preparation with the student pilot for circuit flights in the required extent. Since this was not the first flight of this particular crew, it is very likely that they either did not perform the take-off weight calculation or ignored the result of the calculation.
After take-off from RWY 06, the instructor, probably to avoid unpleasant take-offs and landings against the sun, correctly decided to continue flying on the circuit on RWY 24. With regard to the other two aircraft near the airport, the instructor decided to issue instructions by radio to their crews. It was probably a spontaneous decision, not supported by any regulation.
The critical situation occurred in the climb phase immediately after take-off, when the UL aircraft was in the area above the road connecting the town Hořovice with the village Tlustice at an altitude of about 50 m AGL and was flying in the runway course. At this stage of the flight, the UL instructor probably took control of the aircraft. Both witnesses, the ARV female pilot and male pilot, agree in their statements that they heard the irregular running of the engine and saw how the UL aircraft stopped climbing and started to make a right turn, which was initially smooth but at low speed. The statements also coincide with the security camera footage, which shows the initiation of a right turn with a small roll and a very gradual descent, which only in the area of the southern edge of the village Tlustice turned into a steep wing dive with a subsequent transition to a right spin. After less than one turn, the UL aircraft crashed at a steep angle into an obstacle on the ground.
From the analysis of the data obtained from the instructor’s mobile phone, the critical phase of the flight refers to the last 18 seconds of the recording. For the first 14 seconds, a smooth right turn was performed, during which a 116° course change occurred. At the 14th second, the instructor stopped the turn in the course of 356°, made a 35° left turn and continued with straight flight for 3 seconds in the course of 321°. In the 18th second, he made a course change of 14° to the right to the course of 335°. During this manoeuvre, the UL aircraft probably fell during the increased roll and low airspeed in the turn with subsequent transition to a spin. The record also shows that for the entire 18 seconds of the critical phase of the UL flight the aircraft was flying at GPS speeds of 88 to 103 km∙h-1. With regard to the variable wind speed up to 7.2 km∙h-1 it can be stated that the instructor did not maintain the specified IAS descent speed of 110 km∙h-1 during an engine failure in accordance with the Flight Manual. Once the UL aircraft went into a wing dive, the instructor, given the altitude of the flight, could not have prevented the impact with an obstacle.
The meteorological conditions were suitable for the flight. The flight was carried out under optimal weather conditions. Weak surface wind and good visibility did not impair the UL aircraft piloting.
Conclusions/Causes
The cause of the air accident was a faulty reaction of the intoxicated instructor to the irregular engine operation and his incorrect decision to perform a 180° turn above the airport shortly after take-off. During this manoeuvre with an overloaded ARV, the UL aircraft lost speed and subsequently wing fell into a spin.
Safety Recommendation CZ-24-0004
On the basis of the serious facts found during the investigation of the air accident, the Air Accidents Investigation Institute recommends the Light Aircraft Association of the Czech Republic to amend the directive LA 1 Organisational System and Procedures for the Provision of Defined Activities of LAA ČR in the Administration of ARV, Title 4 Control System of the LAA ČR Administration, with a unified methodology of continuous inspections of the training sessions for ARV pilots in pilot training centres.