CHI04LA158 · Monocoupe Aircraft 90AL-115
Monocoupe Aircraft 90AL-115 · Accident: in flight collision with terrain/water while maneuvering
From Creve Coeur Airport (1H0) to Creve Coeur Airport (1H0)
Event
- NTSB case
- CHI04LA158
- 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
- 2 · 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
Monocoupe Aircraft 90AL-115
- Aircraft type
- Monocoupe 90
- 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
- N1161
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Creve Coeur Airport (1H0), Maryland Heights, MOTo Creve Coeur Airport (1H0), MO
- 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
- Maneuvering
- 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 collision with terrain/water
- 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 › Altitude/clearance, not maintained
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The airplane impacted terrain while maneuvering during a local area flight. Primary aircraft radar track returns were used to reconstruct the accident flight because the airplane was not equipped with a transponder. No altitude information was available with primary radar data. The plotted data showed the accident airplane performing several 180-degree turns within a 1.4 nm square area. The airplane's calculated ground speed varied between 74 and 146 knots during the series of 180-degree turns. The data indicated that the ground speed decreased to approximately 75 knots when the airplane was turning. The ground speed increased to 111-146 knots during the straight flight paths between turns. An on-site survey of the wreckage determined that all primary airframe structural components, flight control systems and powerplant components were present. Flight control cables were inspected and all breaks were consistent with an overload failure. No discrepancies were found with the airframe, flight control systems, engine or propeller that could be associated with a pre-impact malfunction.
Probable cause
The pilot's failure to maintain altitude/clearance from the terrain while maneuvering.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI04LA158
- Event ID
- 20040625X00870
- Case number
- CHI04LA158
- 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, 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: 81dafed9cf66f8f0737dab10352e1dd2f7160849da6bb694d01646a9a68e5eaf; retrieved 2026-09-20T18:26:25.954Z.