SEA04LA100 · Gann Glasair II-S RG
Gann Glasair II-S RG · Accident: in flight encounter with weather en route
From Portland International Airport (PDX) to 2V2 · Longmont, CO
Event
- NTSB case
- SEA04LA100
- 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
- 1 · 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
- Instrument Meteorological Cond
Gann Glasair II-S RG
- Aircraft type
- Gann GLASAIR II-S RG
- Category
- Airplane
- 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
- N711LN
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Portland International Airport (PDX), Portland, ORTo 2V2 · Longmont, CO
- 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
- En route · cruise
- First occurrenceThe 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
- In flight encounter with weather
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Stall/spin
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Pilot in command › Airspeed(vs), not maintained
- Pilot in command › In-flight planning/decision, inadequate
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
While cruising at 14,000 feet, the pilot requested a climb to 17,000 feet. Just after being cleared to climb to that altitude, the pilot advised Center that he was experiencing light to moderate airframe icing. He continued on course to 17,000 feet, and about five minutes after receiving the climb clearance he transmitted that he was in a bad spin. One minute and 20 seconds later the aircraft passed through 5,200 feet, and ten seconds later was lost from radar at an undetermined altitude. The pilot made two other transmissions during the uncontrolled descent, during both of which he stated that he was in a bad left spin. Federal Aviation Administration records indicate that the air mass that the pilot was flying through was moist and unstable. Numerous AIRMETS were in effect for the general area in which the flight was taking place.
Probable cause
The pilot's inadequate in-flight planning/decision and his failure to maintain an airspeed above stall speed (Vs) after encountering airframe icing during cruise flight. Factors include the pilot's intentional continuation of his flight along the planned route after encountering icing conditions.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA04LA100
- Event ID
- 20040608X00753
- Case number
- SEA04LA100
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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: local date, investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2004-06-06.
- API snapshot SHA-256: 6320317eec6af671b4771f0b54e990983c69533ad94fd17f175c279f4212fd70; retrieved 2026-09-20T18:27:19.759Z.