Covering form of preliminary or final report

Date of event:	2020.08.06
Incident number:	CZ-20-0457
Report:	Final report
Place of event:	Kolin airport
Registration mark:	Accident
Weight category MTOM::	<2250 kg
Type of operation:	Recreational and sport aviation
Plane / SFM:	Gliders
Type of plane / SFM:	VSO-10C Gradient
Health effects of event:	Without injury
PDF document:

Description:

SUMMARY

Synopsis

On 6 August 2020, the AAII was notified of an air accident of the VSO-10C GRADIENT glider at the Kolín airport. The glider reached the second third of RWY 03R at higher speed when touching down. In order to prevent the glider from running off the runway and subsequent hitting an obstacle, the pilot executed a ground loop about 50 m before the end of the runway. The glider was seriously damaged during this manoeuvre. The pilot was not hurt.

 

Factual Information

The pilot participated in a flying event organised by the Aeroklub Kolín z.s. at LKKO on 6 August 2020. Upon arrival at the airport, he familiarised himself with the meteorological and air situation for the planned overflight to LKMB. After taking off in the aerotow from RWY 21 LKKO at 13:00 at 850 m MSL, he released the towline from the tow plane and continued into the thermal lift. After reaching the altitude of 1,500 m, the MSL departed the LKKO ATZ and continued flying towards LKMB. Due to deteriorating thermal conditions on the flight route, the pilot decided to return to the LKKO ATZ at Milovice airport level. Here, in the area between LKKO and Kutná Hora, he was flying in thermal lifts for about 90 min and after 3 h and 20 min from take-off he decided to land at the Kolín airport. "At an altitude of approximately 400 m above the airport, according to the Kolín frequency interception, I found that another glider was at approximately the same flight altitude and its pilot was testing a laminate glider for the first time, so I decided to make a high-speed landing to clear the entire length of the runway. I entered the approach pattern, the right-hand downwind position of runway 03, at 300 m above the airport. Because of my intention to land on runway 03 in a long landing with a runout to the end of the runway, I did not extend long enough for this type of aircraft. However, since I mostly fly aircraft with noticeably more effective airbrakes (Jantar 2, Dimona H 36), I did not consider this to be significant and expected a steeper angle of descent. The calculations I had made were for the middle of runway 03. However, almost immediately after deploying the airbrakes, I realised that I would have a problem slowing the airplane down. At first I applied slip for about 1 to 2 sec, but then realised that it was almost ineffective on a VSO-10 glider, so I increased the speed to get the airplane on the ground. I touched down at about 2/3 of runway 03 at a higher speed of about 100 km∙h-1 and began to brake. Approximately 40 to 50 m before the runway 03 stopend, beyond the edge of which there was a fully grown vegetation of tall corn, I decided to put the wing on the ground in order to avoid a head-on collision with the vegetation. Almost immediately the aircraft went into a ground loop, the lift on the accelerated wing caused the glider to lift and turn 180° and land first on the nose and then on the tail skid."

 

Analyses

On returning from an aborted overflight completed with a local flight in thermal lifts, the pilot decided, given the air situation over the airport, to make a landing on RWY 03R to create as much clearance as possible for the glider landing behind him. He initiated turn 3 of the RWY 03 right-hand circuit too early given the current flight altitude, and only realised that the landing would be too long when the aircraft was in the final approach position with the airbrakes fully extended. He therefore attempted to adjust the calculation with a slip, which is not a very effective manoeuvre for achieving a loss of altitude in the VSO-10 type. He then carried out a nose-down push below the horizon and landed on the main landing gear at an increased speed. Although he applied the main gear wheel brake, the glider speed did not decrease significantly during the runout. Due to the approaching of the runway stopend and the mature corn vegetation barrier on the northeast edge of the airport, the pilot decided to change the direction of the glider’s ground movement by placing the left wing tip on the ground. The glider immediately went into a left rotation around the end of the left wing half and executed a turn of approximately 180°. The accelerated right-wing half created sufficient lift to lift the glider from the ground. After this unusual manoeuvre, the glider hit the ground hard, first with the nose, then with the tail
and came to a stop.

 

Conclusions/Causes

The cause of the air accident was an improperly executed landing calculation which forced the pilot to abort the landing with an emergency manoeuvre that caused serious damage to the glider.

 

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.