HPH SPOL SRO GLASFLUGEL 304 MS near Rifle, CO — 2022-06-09

Probable cause

The glider’s encounter with gusting tailwind and downdraft conditions that the pilot was unable to overcome.

NTSB narrative

As the pilot maneuvered the glider in the airport traffic pattern, he radioed that he experienced a heavy sink rate. Shortly thereafter, the glider impacted the ground on airport property. Airport and weather surveillance cameras recorded blowing dust indicating gusting wind. Further meteorological reports supported the possibility of wind speeds up to 67 knots due to a downdraft, outflow boundary, or gust front. Airport surveillance video showed the glider descend in a left wing low, nose low attitude before it struck the ground. About the same time a dust cloud was seen on the video travelling the same direction as the glider, indicating a tailwind. Postaccident examination of the glider did not reveal any mechanical malfunctions or failures that would have precluded normal operation. The examination also revealed that the glider’s retractable engine was stowed within the aft fuselage and was not available to enhance the glider’s climb capability. The accident occurred at the end of a flight that exceeded 5 hours in duration, and it is unknown if the pilot had access to or had received updated weather information during the flight. The terminal area forecast before departure did not indicate a chance of precipitation or rain showers for the accident site. However, about 4 hours before the accident it was updated to include the potential for convective activity. Based on the available evidence, the glider entered an area with weather conditions that included downdrafts and wind gusts, that the pilot could not overcome before the glider impacted the ground.

Analysis

Primary failure mode

Controlled flight into terrain

First missed decision gate

Pilot reported heavy sink but continued approach instead of aborting.

NTSB coding

• Loss of lift · Approach-VFR pattern base

Evidence available

• Video
• ADS-B / radar
• Photos
• 15 docket documents

Docket documents15

• RELEASE OF AIRCRAFT WRECKAGE, NTSB FORM 6120.15form
• AIRCRAFT EXAMINATIONother
• AIRPORT CTAF AUDIOother
• WEATHER ATTACHMENT 1other
• WEATHER ATTACHMENT 2other
• WEATHER ATTACHMENT 3other
• WEATHER ATTACHMENT 4other
• WEATHER ATTACHMENT 5other
• WEATHER ATTACHMENT 6other
• WEATHER ATTACHMENT 7other
• PHOTOSphotos
• ADS-B DATAradar
• TOXICOLOGICAL REPORTreport
• WEATHER FACTUAL REPORTreport
• AIRPORT SURVEILLANCE VIDEOvideo

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