Covering form of preliminary or final report
| Date of event : | 2021-09-04 |
| Incident number : | CZ-21-0644 |
| Report : | Final report |
| Place of event : | On the field approx. 1 km north of Žilina near Kladno |
| Registration mark : | Accident |
| Weight category MTOM: : | <2250 kg |
| Type of operation : | Recreational and sport aviation |
| Plane / SFM : | Airplanes |
| Type of plane / SFM : | Cessna 152 |
| Health effects of event : | The fatal injuries |
| PDF document : | 
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Description:
SUMMARY
Synopsis
On 4 September 2021, the AAII was notified of an air accident of Cessna 152 on the field approx. 1 km north of Žilina near Kladno. The aircraft pilot and another person on board (hereinafter the “navigator”) participated in the Zdeněk Běhounek’s Memorial Trophy 2021 held by AK Kladno, z.s. The competition navigation flight was conducted along the planned flight route with search for ground targets. Before the last check point, while flying eastward, the aircraft’s speed dropped down significantly. The aircraft entered a dive and subsequently into a nosedive. While recovering the nosedive, the aircraft continued in a steep climb at an angle of approximately 50–60 degrees with a smooth change of heading to the north. At the peak of the climb, the aircraft lost speed, and fell to the left, partially over the back.
During the dive, the aircraft made about 1/4 turn of the left spin suddenly changing into fully perpendicular position of the nose to the ground. At a blunt angle, the aircraft, in a slight positive roll, crashed with the right edge of the elevator onto the ground at great vertical velocity. It continued rotating over the right wingtip arc and the propeller, and, having landed on the main landing gear, it stopped with its nose heading southwest, approx. 20 m from the place of its first contact with the ground.
The aircraft was destroyed. The crew suffered injuries incompatible with life.
Factual Information
Description of the event flight based on an analysis of data from the flight recorder. The crew took off from LKKL RWY 30 at 11:20:10 and continued westward to the starting point (SP). The pilot was circling in the left turn for 3.5 minutes in front of SP and then joined the competition route over SP at 11:25:00. He flew over each waypoint (WP) at following times: 1. WP 11:31:40, 2. WP 11:47:00, 3. WP 11:55:40, 4. WP 12:03:10, 5. WP 12:13:20. Having flown over the fifth waypoint, the crew continued in flight in the eastern direction towards the target point (TP). During this leg, the aircraft was moving at GS GPS 70–65 kt at GPS level of 2,100–2,150 ft. From 12:18:30 to 12:18:50, the heading kept changing, and from 12:18:45 to 12:18:56, GS GPS was gradually decreasing from 65 kt down to 36.5 kt. From 12:18:56 to 12:19:04, the GPS level went from 2,143 ft down to 1,803 ft, where the recording ends.
Analyses
The pilot was a holder of the Private Pilot Licence PPL (A) with the valid qualifications SEP LAND. Since 2009, when he started his practical flight training in Cessna 152, he had flown 200 hours. He did not fly on any other aircraft types, except Cessna 172 and 152; and he had gained some experience in flying Cessna 152. Although he did have practical experience of flying the type, he was probably unaware of the negative effect of exceeding the maximum take-off weight and its distribution and associated problems in controlling the aircraft in critical situations.
In the right seat, there was a man who acted as a navigator during the competition flight of two-member crews. His body weight contributed to the resulting excess of the maximum take-off weight and adversely affected the centre of gravity position for the given flight.
According to the flight recorder data, the critical situation occurred during the execution of a horizontal S-turn manoeuvre with simultaneous reduction of airspeed in order to accurately hit the target point. During the mode change, the pilot extended the flaps to 10° and balanced the aircraft as tail-heavy. During performing these operations, from 12:18:45 to 12:18:56, the aircraft flew at an altitude of approximately 800 ft above the terrain and gradually reduced the GS GPS airspeed from 65 kt to 36.5 kt. The pilot was probably so focused on reaching the target point as accurately as possible that he did not notice the critical drop in speed
and the overloaded aircraft spontaneously went into a wing dive and then into a nosedive. This is also evident from the last 6 sec of the recording showing the aircraft lost 340 ft over that time span. The pilot clearly failed to recover from the dive and gradually lost control of the aircraft. According to the testimony of witness 1, a professional pilot with experience on the type, after the dive, the aircraft continued in a steep climb at an angle of approximately 50–60 degrees with a smooth change of heading to the north. At the peak of the climb, the aircraft lost speed, and fell to the left, partially over the back. During the dive, the aircraft made about 1/4 turn of the left spin suddenly changing into fully perpendicular position of the nose to the ground. The traces found at the site of the accident showed that the first contact with the ground was made at a low forward speed with a large vertical descent. The aircraft in a right roll struck the ground with the right edge of the elevator. It continued rotating over the right wingtip arc and the propeller, and, having landed on the main landing gear, it stopped with its nose heading southwest, approx. 20 m from the place of its first contact with the ground.
Conclusions/Causes
The cause of the accident was an incorrect manoeuvre in reaching the target point as accurately as possible. An overloaded and unbalanced aircraft flying at a low speed entered into a dive and subsequently into a nosedive. Despite sufficient altitude above the terrain, the pilot was unable to respond correctly to the situation and resolve the unusual situation.
Safety Recommendations
In view of the finding that all the participants of the 55th Zdeněk Běhounek’s Memorial Trophy 2021 made competition flights with aircraft with the on-board secondary surveillance radar transponders switched off and the competition organiser failed to address this unsafe practice, the AAII issues Safety Recommendation CZ-22-0007.
Safety Recommendation CZ-22-0007
The AAII recommends that the organiser of the Zdeněk Běhounek’s Memorial Trophy, Aeroklub Kladno, z.s., should consider requesting the Air Navigation Services of the Czech Republic to declare the area for the competition flights at the time when those are held. This operational measure would ensure that the crews of the competition aircraft would not intentionally violate Rule of the Air L 8168/III and endanger the operation of other air traffic participants.
Attached final report in PDF file is in original Czech language.