WPR13CA418 · Grob G 103 TWIN II
Grob G 103 TWIN II · Accident: landing area undershoot
From Morgan County Airport (42U) to Morgan County Airport (42U)
Event
- NTSB case
- WPR13CA418
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Grob G 103 TWIN II
- Aircraft type
- Grob G-103
- Category
- Glider
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N54554
- Operator
- Daniel R Thirkill · private individual
- Onboard fatalities
- Unknown
- Route
- From Morgan County Airport (42U), Morgan, UTTo Morgan County Airport (42U), Morgan, UT
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Landing
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Landing area undershoot
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft oper/perf/capability
- Personnel issues › Action/decision
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
When the student pilot realized his glider was high on final approach, he lowered the nose and deployed the spoilers, which increased the rate of descent and airspeed in excess of what was required. After the flight instructor had the student close the spoilers, the glider encountered turbulence and a sink rate that put them at a low approach altitude, about 150 feet above ground level. The flight instructor then took control and performed an off-airport landing. During the touchdown the glider impacted a large shrub bush with its right wing, slid sideways through a second bush, and then completed a 270-degree turn before coming to rest upright. The impact with the shrub resulted in substantial damage to the leading edge of the right wing. The flight instructor reported no preimpact mechanical malfunctions or failures with the glider that would have precluded normal operation.
Probable cause
An incorrect descent rate while on final approach as a result of the flight instructor's delayed remedial action, which lead to an off-field landing and impact with terrain.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR13CA418
- Event ID
- 20130922X10314
- Case number
- WPR13CA418
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 12a943444e4bddd9518e5804a1f6c3b3beff79adb177c31ded5d586bf3c8886d; retrieved 2026-09-15T22:53:39.650Z.