Covering form of preliminary or final report
| Date of event : | 2020-04-24 |
| Incident number : | CZ-20-0197 |
| Report : | Final report |
| Place of event : | Kyjov airfield |
| Registration mark : | Accident |
| Weight category MTOM: : | <2250 kg |
| Type of operation : | Recreational and sport aviation |
| Plane / SFM : | Sports flying machines |
| Type of plane / SFM : | UL airplane Bristell ELSA |
| Health effects of event : | The fatal injuries |
| PDF document : | 
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Description:
Description:
On 24 April 2020, the AAII was notified of an air accident of the Bristell ELSA UL aircraft at LKKY. The ARV pilot (hereafter the “pilot”) and the pilot-instructor (hereinafter the “instructor”) were performing a check flight before a flight with another person on board focusing on emergency procedures in accordance with the Aeroklub Kyjov operating guidelines.
The crew took off from the taxiway and started climbing in a prescribed manner above the airport up to 1,800 ft ALT. In the area of the third circuit turn of RWY 33, the instructor turned off the engine and the pilot, having adjusted the calculation, sideslip landed the UL aircraft on the second third of RWY 33.
During the run, the crew started the engine, set the flaps for take-off, lifted the UL aircraft, and started smoothly ascending in the runway heading. At the altitude of approximately 30 m AGL, a wing stall occurred. The UL aircraft crashed with the front fuselage part onto the ground at a steep angle and bounced off. After a brief rebound, the aircraft fell on the main undercarriage and caught fire. Due to the crash to the ground and subsequent fire, the UL aircraft was totally destroyed. The crew suffered injuries incompatible with life in the UL aircraft wreckage.
On the same day, the Police of the Czech Republic, the FRS unit, the AAII inspector, the LAA CR inspector, and the forensic doctor arrived at the location of the air accident and performed professional investigation.
SUMMARY
Synopsis
On 24 April 2020, the AAII was notified of an air accident of the Bristell ELSA UL aircraft at LKKY. The ARV pilot (hereafter the “pilot”) and the pilot-instructor (hereinafter the “instructor”) were performing a check flight before a flight with another person on board focusing on emergency procedures in accordance with the Aeroklub Kyjov operating guidelines.
The crew took off from the taxiway and started climbing in a prescribed manner above the airport up to 1,800 ft ALT. In the area of the third circuit turn of RWY 33, the instructor turned off the engine and the pilot, having adjusted the calculation, sideslip landed the UL aircraft on the second third of RWY 33.
During the run, the crew started the engine, set the flaps for take-off, lifted the UL aircraft, and started smoothly ascending in the runway heading. At the altitude of approximately 30 m AGL, a wing stall occurred. The UL aircraft crashed with the front fuselage part onto the ground at a steep angle and bounced off. After a brief rebound, the aircraft fell on the main undercarriage and caught fire. Due to the crash to the ground and subsequent fire, the UL aircraft was totally destroyed. The crew suffered injuries incompatible with life in the UL aircraft wreckage.
On the same day, the Police of the Czech Republic, the FRS unit, the AAII inspector, the LAA CR inspector, and the forensic doctor arrived at the location of the air accident and performed professional investigation.
Factual Information
At approx. 15:55, the crew took off from the NOVEMBER taxiway and continued climbing in a left turn until the position approx. 1 km south-west of the airport where it was smoothly making a right turn by 360 degrees. Having completed the turn, the UL aircraft continued ascending up to 1,800 ft ALT directly above the middle of the airport. During this manoeuvre, the UL aircraft was flying at the ground speed of 100 kt, and later dropped down to 50 kt. Having passed the middle of the airport, the instructor turned off the engine and the UL aircraft was smoothly descending to the area of the third turn of the right circuit of RWY 33. The pilot continued the landing manoeuvre. Having adjusted the calculation, he sideslip landed the UL aircraft on the second third of RWY 33.
During the run, the crew started the engine, set the flaps for take-off, lifted the UL aircraft, and started smoothly ascending in the runway heading. At the altitude of approximately 30 m AGL, a wing stall of the UL aircraft occurred. The UL aircraft crashed in a left rotation at a steep angle first with the front fuselage part, then the left fuselage part and finally the right part of the wing on the ground and bounced off. After a brief rebound, the aircraft fell on the main undercarriage and caught fire.
Analyses
The pilot was fit to fly and was a holder of adequate qualification for performing flights with the Bristell ELSA UL aircraft. The pilot underwent the theoretical and practical training in the extent necessary to acquire the Private Pilot Licence according to the Ultralight Aircraft Pilot Syllabus approved by the LAA CR. He was smoothly fulfilling individual tasks prescribed by the approved air training syllabus without any problems. He mostly received excellent grades. After he had acquired his pilot licence, he continued flying consistently and without major breaks in order to achieve the prescribed quota of flight hours for the performance of familiarisation flights. He had piloted the Bristell ELSA UL aircraft for one year. According to the aircraft logbook records, he flew in the period from 1 February 2020 to 17 April 2020 in total 10 hrs 42 min and carried out 18 flights. He had many years of experience in handling and piloting gliders where he served as an instructor.
The instructor, i.a., worked as a professional transport pilot and held a valid Medical Certificate, Class 1. The forensic medical examination revealed that he had been taking SSRI antidepressants for unknown reasons for a prolonged period of time without first consulting the aviation medical examiner and/or the aeromedical centre. The instructor had many years of experience with training of pilots of single-pilot aircraft for general aviation. According to the pilot logbook entries, he flew in the period from 25 March 2020 to 18 April 2020 on aircraft Zlín Z-43, Z-226 MS, and Tecnam P-92 JS in total 40 hrs 35 min out of which 39 hrs 50 min as an instructor. He was intensively engaged in ARV pilot training since his transition training for Bristell ELSA UL aircraft in 2019. According to the aircraft logbook records, he flew in the period from 11 April 2020 to 23 April 2020 on UL aircraft Bristell ELSA in total 23 hrs 04 min, in all cases in the position of an instructor.
The manufacturer as the owner always repaired and eliminated any and all defects on the UL aircraft recorded in the aircraft logbook. No record was found in the aircraft logbook about problems with the operation of flaps. No defects were mentioned in the aircraft logbook from the operation period after the annual technical inspection. The pilots flying the UL aircraft on the day of the air accident did not notice any defects or problems with its piloting. In their statements, they confirmed that the power unit and individual control elements were working without any defects. Upon investigation of UL aircraft wreckage at the place of air accident and subsequent technical investigation of the UL aircraft wreckage at the place of its deposition, technical investigation did not detect any facts that would indicate that the air accident was caused by a technical defect. The foot control cables for rudder control were not cut until handling of the wreckage.
The critical situation occurred during the climb phase immediately after take-off, when the instructor probably simulated an engine failure by decelerating the throttle and idling while the examined pilot did not correctly change the flight mode of the UL aircraft from climb to gliding flight. According to a witness’ statement, the UL aircraft went into a left wing stall with the nose on the horizon, most certainly not below the horizon or not significantly below the horizon. The UL aircraft was located in the area behind the runway, where the instructor usually performs a simulated engine failure, but with regard to the method of take-off did not reach such altitude as would be the case when using the entire length of the runway. The pilot was probably surprised by the low altitude and instead of first changing the UL aircraft into gliding mode of flight by adequate control lever depression, he reacted with inappropriate interference with the transverse, and especially directional control, by intending to turn to the area on the left of the extended RWY 33 axis. This area is usually used by AK Kyjov pilots for emergency landing training after simulated engine failure after take-off from RWY 33 LKKY. Insufficient speed in combination with a left tilt turn with a large pitch, exceeded maximum take-off weight of the UL aircraft and turbulent flow behind the terrain obstacle caused a left wing stall with a subsequent impact on the ground at a steep angle. Experience from the operation of the Bristell ELSA UL aircraft shows it is proven that after deceleration of the gas to idle while maintaining the recommended climb speed of 120 km∙h-1, the UL aircraft decelerates to speeds lower than 100 km∙h-1 within 2–3 seconds if the pilot does not respond correctly and in time by depressing the control lever.
Conclusions/Causes
The cause of the accident was an incorrect change of the UL aircraft flight mode from climb to glide in a simulated engine failure shortly after take-off, which resulted in a loss of speed and the subsequent UL aircraft wing stall.
Safety Recommendations
Given the circumstances of the air accident, the AAII issues no safety recommendations.
Attached final report in PDF file is in original Czech language.