SEA99LA087 · Let L-13
Sunbird Aviation Let L-13 · Accident: on ground/water collision with object during landing
From Bozeman Yellowstone International Airport (BZN) to an unrecorded destination
Narrative check · The NTSB narrative appears to contradict this record's aircraft involved. Values are shown as recorded, not corrected; compare with the narrative.
Event
- NTSB case
- SEA99LA087
- 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
- 0
- 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
Let L-13 Possible conflict
- Aircraft type
- Let L-13
- 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
- N70741
- Operator
- Sunbird Aviation
- Onboard fatalities
- Unknown
- Route
- From Bozeman Yellowstone International Airport (BZN)To not recorded
- 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 · landing roll
- 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
- On ground/water collision with object
- 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
- Pilot in command(cfi) › Altitude/clearance, not maintained
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
After performing two 360 degree turns on base leg before turning final due to traffic which had not cleared the runway, the glider was cleared to land. Ground control asked him to immediately remove the glider off the north side of the runway upon rolling out. The student was flying the glider at that time. The tow pilot entered the runway in front of the glider and motioned to turn the glider off the runway. The glider flight instructor said that he started to give instructions to the student to put the left wing down to start the turn, but realized they were going too fast to safely make a turn without hitting the tow pilot. The instructor took the controls and tried to make a right turn away from the tow pilot and tow plane, but toward the runway. The wing tip of the glider struck the prop of the tow plane and caused damage to the underside of the glider's wing. The tow pilot noted that he assumed the tower would have told the glider pilot the same instructions he had received. He said he expected the glider pilot to be prepared for his hand signals directing him off of the runway. The tow pilot believed that, not having been briefed by the tower, the glider was landed longer and faster than usual to fit the flight instruction that the student required. The instructor said that while the instructions from the tower were distracting and caused the glider to be low on final, ' I think the communication to the tow pilot (and not the glider) caused the tow pilot to enter the runway and caused the evasive maneuver that contributed to the accident. Despite the confusion a safe landing was underway until that time; I should have rolled out straight ahead and made the tow pilot jump clear and then the collision would have never occurred.'
Probable cause
The pilot in command's failure to maintain clearance from a parked airplane during his attempt to avoid a person on the runway.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA99LA087
- Event ID
- 20001212X19117
- Case number
- SEA99LA087
- 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: investigation status. 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: 32ce00754d91ce85beec5168614a83dddbf2d55a57fc0f4b963527616f7d19be; retrieved 2026-09-22T14:49:19.567Z.