Accident Schleicher ASK-16 HB-2033, Thursday 6 January 2022
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Date:Thursday 6 January 2022
Time:15:35 LT
Type:Silhouette image of generic AS16 model; specific model in this crash may look slightly different    
Schleicher ASK-16
Owner/operator:Segel- und Motorfluggruppe Grenchen
Registration: HB-2033
MSN: 16026
Year of manufacture:1974
Fatalities:Fatalities: 0 / Occupants: 1
Other fatalities:0
Aircraft damage: Substantial
Location:Obersee, SZ -   Switzerland
Phase: Take off
Departure airport:Wangen-Lachen Airfield (LSPV)
Destination airport:Grenchen Airport (ZHI/LSZG)
Investigating agency: STSB
Confidence Rating: Accident investigation report completed and information captured
The motor glider lost power during takeoff from Wangen-Lachen Airfield (LSPV) shortly after takeoff. The aircraft sank and came to rest in the water of the Obersee lake.
The pilot was not injured.

Analysis and Conclusion:
The ground roll until reaching a groundspeed of 70 km/h was approximately 200 m, which is expected according to the takeoff distance calculation. Up to this point, there was no deterioration in the takeoff performance, such as carburetor icing. However, the takeoff performance significantly deteriorated afterward: the powered glider only lifted off after an additional 180 m at a groundspeed of 83 km/h and did not gain any further speed, remaining a few meters above the ground within the ground effect.

The pilot did not perceive any unusual engine sounds and did not change the throttle position until touchdown on the water. Therefore, it is highly likely that the deterioration in takeoff performance after reaching 70 km/h cannot be attributed to a technical cause. Due to the characteristics of the wing profile, it is expected that residual moisture on the wings increased the required takeoff speed beyond the specified 70 km/h for a normal takeoff, impairing the takeoff performance.

Accident investigation:
Investigating agency: STSB
Report number: 
Status: Investigation completed
Duration: 1 year and 5 months
Download report: Final report

Sources:;art146989,1368295 (photo)


Revision history:

06-Jan-2022 16:08 gerard57 Added
06-Jan-2022 16:52 harro Updated [Aircraft type, Registration, Cn, Source, Plane category]
06-Jan-2022 16:58 harro Updated [Operator, Source, Embed code, Narrative, Category]
06-Jan-2022 20:18 gerard57 Updated [Total occupants]
06-Jan-2022 21:14 RobertMB Updated [Time, Operator, Location, Departure airport, Source, Narrative]
09-Jan-2022 15:49 Captain Adam Updated [Narrative]
17-Feb-2022 19:35 harro Updated [Time, Destination airport, Source, Damage, Narrative]
13-Jun-2023 16:11 harro Updated

Corrections or additions? ... Edit this accident description

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